bluuebunny/crossref_metadata_2025 huggingface dataset:
Static Response of Stiff-Cored Unsymmetric Sandwich Beams
Authors: Rao D. K.
Published: November 2010

Improved equations governing the deflection of an unsymmetric sandwich beam (which include the effect of extensional and bending rigidities of its stiff core) are derived using a variational method. The effect of face-thickness ratio on the contribution of the core to the overall flexural rigidity is studied. Numerical results for simply supported and fixed-fixed beams subjected to a uniformly distributed load are obtained by using Laplace transforms. These results show that ignoring the bending and extensional effects of a stiff core can cause errors in maximum deflections as high as 20 percent. The corresponding errors in stresses are very high, and they vary from 10 to 150 percent. Hence, it is suggested that the extensional and bending effects of the core should be taken into account when one is interested in calculating the maximum stresses in stiff-cored beams.
Grinding of Glass: Surface Structure and Fracture Strength
Authors: Huerta M. , Malkin S.
Published: November 2010

An investigation is described of the surface structure and fracture strength for grinding of glass under various conditions. The surface structure of finished glass surfaces was examined by scanning electron microscopy. Surfaces ground using a silicon carbide wheel exhibited extensive flow over the surface, while surfaces ground with diamond wheels appeared to have been generated by brittle fracture with some evidence of localized flow. The relative amounts of flow and fracture on the diamond ground surfaces for various grinding conditions are related to the number of cutting points per unit area of finished surface. Grinding conditions resulting in relatively more flow were generally found to lead to higher fracture strengths.
Vibration Analysis of Axial Flow Turbine Disks Using Finite Elements
Authors: Wilson G. J. , Kirkhope J.
Published: November 2010

The finite element method is applied to the vibration analysis of axial flow turbine disks. Using the axi-symmetric properties of the configuration of such disks, several finite elements are developed to describe the bending of thin or moderately thick circular plates, and which are characterized by only four- or eight-degrees-of-freedom. These elements incorporate the desired number of diametral nodes in their dynamic deflection functions, and allow for any specified thickness variation in the radial direction. In addition, the effects of in-plane stresses which might arise from rotation or radial temperature gradient, and the effects of transverse shear and rotary inertia in moderately thick plates are readily accounted for. The accuracy and convergence of these elements is demonstrated by numerical comparison with both exact and experimental data for disks.
Efficient Optimal Design of Suspension Systems for Rotating Shafts
Authors: Pilkey W. D. , Wang B. P. , Vannoy D.
Published: November 2010

A new technique is proposed for the optimum design of suspension systems for rotating shafts. In this approach the conventional method of trial and error search for optimum parameter values for a prescribed design configuration has been replaced by an efficient two-stage procedure. In the first stage a generic force is substituted for the suspension system to be designed and the absolute optimum (or limiting) performance characteristics of the shaft are computed. In the second stage, using a chosen suspension system configuration, parameter identification techniques are applied to find the design parameters so that the suspension system will respond as close as possible to the absolute optimal performance. In this approach the repetitive shaft analyses required in the conventional search techniques are avoided. Hence, the new technique is relatively efficient computationally and is suitable for large systems. Both linear and nonlinear suspension systems can be designed. A simple Jeffcott rotor is used to demonstrate the new technique.
Dynamic Acceptance Tests for Horizontal Milling Machines Based on a Statistical Theory of Machine Tool Chatter
Authors: El Baradie M. A. , Sadek M. M. , Tobias S. A.
Published: November 2010

Machine tool chatter is essentially a statistical phenomenon. The dynamic characteristics of machine tools as well as the dynamic coefficients of the cutting process are statistical quantities which show scatter when determined in repeated tests. They can therefore be specified only in terms of mean values with confidence limits. The statistical theory of chatter developed in this paper deals with the scatter of dynamic data of the machine structure but assumes that the dynamic cutting coefficients have discreet values. This is used for analyzing two series of tests carried out on horizontal milling machines. In the first series a particular machine was tested ten times and from the results thus obtained the mean threshold of stability with its confidence limits was established. In the second series a batch of the same type of machines taken at random were analyzed in a similar manner, with the aim of establishing “type behavior”. In the second series of tests large scatter in the dynamic characteristics was found, causing a large scatter in predicted cutting performance. Thus, machines which have the same specification and which to all appearances are identical may have widely varying resistance to chatter. It is recommended that machines should be “graded” on the basis of the dynamic acceptance tests evolved so as to ensure that the user will obtain “value for money”.
Effect of Sweep and Drag on Hydrofoil Stability
Authors: Mahig J.
Published: November 2010

The stability of hydrofoils is currently estimated by plots of the log decrement versus flutter frequency and forward speed. Herein is suggested a method used by electrical or electronic engineers to determine the relative stability of a linear system. This “root contour” method is discussed and it is shown how it can be applied to a hydrofoil analysis. The strip method of analysis is used with strength of material estimates for foil stiffness. Both drag and sweep angle effects are included in the analysis to determine their effect on foil stability as defined by the root contour method.
Experimental Evaluation of Multiplane-Multispeed Rotor Balancing Through Multiple Critical Speeds
Authors: Tessarzik J. M. , Badgley R. H. , Fleming D. P.
Published: November 2010

Experimental tests have been conducted to further demonstrate the ability of the Influence Coefficient Method to achieve precise balance of flexible rotors of virtually any design for operation through virtually any speed range. Four distinct practical aspects of flexible-rotor balancing were investigated in the present work: (1) Balancing for operation through multiple bending critical speeds; (2) balancing of rotors mounted in both rigid and flexible bearing supports, the latter having significantly different stiffnesses in the horizontal and vertical directions so as to cause severe ellipticity in the vibration orbits; (3) balancing of rotors with various amounts of measured vibration response information (e.g., numbers of vibration data sets, and numbers and types of vibration sensors), and with different number of correction planes; (4) balancing of rotors with different (though arbitrary) initial unbalance configurations. Tests were made on a laboratory quality machine having a 122-cm (48-in.) long rotor weighing 50 kg (110 lb) and covering a speed range up to 18,000 rpm. The balancing method was found in every instance to be effective, practical, and economical, permitting safe rotor operation over the full speed range covering four rotor bending critical speeds.
Criteria for Evaluating Bolt Head Design
Authors: Landt R. C.
Published: November 2010

The emphasis on reducing fastener weight, conserving material, and providing joint integrity has increased the importance of understanding the causes of bolt failure. In bolt design, a significant area where better material utilization can be achieved is the bolt head. This paper identifies the critical factors in head design which affect mechanical properties and presents a design procedure to determine the optimum head configuration.
Automatic Orientation Control Device for Underwater Divers
Authors: Baz A. , Seireg A.
Published: November 2010

This study deals with the development of an orientation device that enables the working diver to control and maintain automatically his spatial orientation underwater. The device can be useful during welding or grinding of ship hulls, salvaging operations, and any underwater activity when a specific special orientation improves the diver’s performance. The device utilizes the natural forces of buoyancy and gravity in its operation to reduce the power requirements and to assure stable performance. Underwater evaluation of an optimally designed prototype of the system shows good potential for the device as a useful tool for the working diver.
Heuristic Combinatorial Optimization in the Kinematic Design of Mechanisms—Part 1: Theory
Authors: Lee T. W. , Freudenstein F.
Published: November 2010

The heuristics developed by Dr. Shen Lin in the communications field have been extended and applied to the design of mechanism. The basic approach involves the use of an intelligent partial search, which moves from randomly selected starting points and is conducted effectively over the entire solution space. It is a non-numerical technique, the convergence of which is essentially independent of continuity, differentiability, or the starting point of the search. The method requires less computational capacity and time than most conventional optimization techniques. It appears well suited for complex (i.e., realistic) mechanisms design. In this part we describe the theory.
High-Speed Films of the Incipient Cutting Process in Machining at Conventional Speeds
Authors: The J. H. L.
Published: November 2010

Investigations of the incipient cutting process have mainly used ductile materials (lead/brass) at low speeds (⩽5 m/s). The present study is more realistic as it uses mild steel (0.45 percent C) at conventional speeds (50-300 m/s). High-speed films and force traces of the incipient stage were taken. Hardness profiles of the chiphead were also constructed. Two types of chip shape were found. One type occurs in the range of lower speeds (⩽150 m/s) with larger depths of cut (⩾0.30 mm/rev). Both types can be explained by the change in relative magnitudes of friction and the cutting force.
Design and Analysis of Multilink Flexible Mechanisms With Multiple Clearance Connections
Authors: Dubowsky S. , Gardner T. N.
Published: November 2010

The problem of predicting the dynamic behavior of general planar mechanisms with elastic links and multiple clearance connections is addressed using a perturbation coordinate approach. Particular emphasis is placed on studying the effects of system elasticity on the high internal impact forces generated by the presence of the clearances at high speeds. Two examples of complete systems are considered and their responses are compared to the behavior of relatively simple dynamic models: the object is the development of design guidelines. The results show that the simpler models yield useful insights into the behavior of the more complex systems.
Delamination Wear of Dispersion-Hardened Alloys
Authors: Saka N. , Suh N. P.
Published: November 2010

In order to investigate the effect of hard incoherent dispersoids on the sliding wear rate of dispersion-hardened alloys, internally oxidized Cu-Cr and Cu-Si alloys were tested. OFHC copper and oxygen doped OFHC copper were also used to compare their wear properties with dispersion-hardened alloys. The results of unlubricated wear tests at room temperature in the load range 2.22–22.2 N (0.5–5.0 lb) at a sliding speed of 3 × 10−2 m/s show that the wear rate is linearly proportional to the normal load. Hard oxide dispersion strengthened alloys exhibited larger wear rates than the soft OFHC copper. Surface and subsurface observations indicate that wear was primarily due to crack nucleation, propagation, and delamination of wear sheets. The wear resistance of the materials decreased with increase in volume fraction of the oxide even when the hardness was increased. It is concluded that because of the immediate debonding between the matrix and the oxide particle, upon plastic deformation of the matrix, crack propagation is the wear rate controlling mechanism in these internally oxidized metals. The results, which are contrary to the prediction of the adhesion theory of wear, are consistent with the delamination theory.
Analytical Design of Cam-Type Angular-Motion Compensators
Authors: Dhande S. G. , Sandor G. N.
Published: November 2010

In this paper, a unified approach is presented for the analytical design of cams used in various angular-motion compensators. These mechanisms can be classified as cam-modulated linkages. For a predetermined phase control between the two coupled shafts of the compensator, using this method one can find the exact equation of the cam profile, its principal curvature at the point of contact, expressions for the pressure angle and the transmission angles, and the condition for maximum pressure angle as well as the cutter wheel positions for generating the cam profile on an appropriate machine tool. The equations developed can be used effectively for analyzing the mechanical error due to tolerances on different dimensions of this cam-modulated linkage. The analysis of three-dimensional cam-type angular-motion compensators is also included.
An Analysis for Plane Strain Plastic Deformation in Metal-Working Process
Authors: Lee Y. S. , Patel M. R.
Published: November 2010

The two-dimensional plane strain equation of large plastic flow, expressed in terms of the stream function gradients, is modified using complex variables. The resulting governing equation is solved analytically for a class of nonlinear materials whose stress-strain rate behavior can be expressed by σ¯ = ce¯˙m. A one-to-one correspondence between the plastic flow equation using the Levy-Mises constitutive relations and the Navier-Stokes equation of fluid flow with zero inertia term is established for constant λ˙. This correspondence allows the existing fluid dynamic solution to be used for the plasticity analysis. An analytical solution of plane strain extrusion of linear material through square-cornered die is presented to illustrate the procedure.
Progress in Railway Mechanical Engineering (1976–1977 Report of Survey Committee) Cars and Equipment
Authors: Manos W. P.
Published: November 2010

This survey of the annual ASME report covers some of the major developments in rail freight and passenger equipment made public in the last calender year. It covers developments worldwide. In the freight area the main developments are aimed at transporting bulk commodities with some thought being given to multipurpose concepts. The passenger developments are continuing in LRVS, rapid transit, and commuters; however, long haul equipment is also being developed.
Theoretical and Experimental Investigation of Continuous Jet Penetration of Solids
Authors: Hashish M. , duPlessis M. P.
Published: November 2010

The study attempts to develop a theory for the penetration of a wide range of solid materials by continuous high-velocity water jets. The theory is based on a control volume analysis to determine the hydrodynamic forces acting on the solid boundaries of the cutting slot. A Bingham model is used to describe the time-dependent stress-strain relationship of the solid material. The coupled fluid-solid mechanics equations are simplified to yield a closed-form solution in the form of a nondimensional cutting equation zdn=1−σcρV122Cf√π[1−e−(2Cf/√π)·(ρV1/η)·(V1/u)] which satisfies all the limiting conditions of practical cutting applications. Published experimental results from cutting tests with a wide range of fibrous, granular and crystalline material are used to obtain mean values of the friction (Cf) and damping coefficients (η) which are used with the compressive yield strength (σc) to characterize different materials. The theory presents a basis for developing more exact cutting equations by choosing the optimum rheological model for a particular material.
Reliability Analysis of Machine Tool Structures
Authors: Rao S. S. , Reddy C. P.
Published: November 2010

A method of estimating the reliability of machine tool structures is developed. The reliability analysis of horizontal milling machines in various failure modes, like static deflection, fundamental natural frequency and chatter stability, is considered for illustration. The table height, distance of the cutter center from the arbor support, damping factor, Young’s modulus of the material and the load acting on the cutter and the table are considered as random variables. The finite-element displacement method is used to idealize the structure. The reliability analysis is based on the linearization of a function of several random variables about the mean values of the random variables. The overall reliability of the machine tool structure is found by treating it as a weakest-link system having several failure modes. A sensitivity analysis is also conducted to find the variaion of reliability with a change in the coefficients of variation of different random parameters.
Optimizing Railroad Freight Car Truck Suspension Systems Having Coulomb Damping
Authors: Bullock R. L. , Cooley D. B.
Published: November 2010

This paper describes the design process followed in developing a 100 ton freight car truck suspension system having coulomb damping. Classical linear vibration analysis was used for the conceptual design phase. Within the constraints placed upon truck suspension systems, a constant damping parameter, i.e., the ratio of friction force to static force imparted by the base, for all load conditions was established as a design goal. Optimization of the actual design parameters and comparison to existing truck suspensions was accomplished using the latest vehicle model developed by the AAR/TTD.
Machine Loading and Product-Mix Analysis for Group Technology
Authors: Hitomi K. , Ham I.
Published: November 2010

An analysis for machine loading was performed to optimally select parts to be manufactured in a limited amount of time available by a given production facility by applying the Group Technology concept. In addition, optimal machining speeds were determined for all products selected, so as to maximize the production rate. A computational algorithm was developed for this optimal machine loading and product-mix decision, and a sample example was demonstrated.
Optimum Design of Bridge Girders for Electric Overhead Traveling Cranes
Authors: Rao S. S.
Published: November 2010

The problem of the design of box-type bridge girders for electric overhead traveling cranes is formulated as a minimum weight design problem with inequality constraints. The restrictions placed on the design problem include limitations on the maximum allowable deflections and stresses as well as on the shock absorbing capacity during accidental collision. The overall stability and rigidity considerations are also taken into account. Several load conditions, as per the code specifications, are considered in the design problem. The resulting nonlinear programming problem is solved by using an interior penalty function method. Numerical examples are given to illustrate the effectiveness of the approach. The resulting computer program is used to make a sensitivity analysis of the problem.
Determination of Dynamic Characteristics of an Impact Forming Machine Structure
Authors: Osman A. E. M. , Knight W. A. , Sadek M. M.
Published: November 2010

The noise generated from an impact forming machine arises mainly from structural vibrations and consequently accurate determination of the modal characteristics of the machine is necessary in order to bring about design modifications with the aim of reducing noise levels. Various methods of dynamic testing are applied to a high speed forming machine structure. It is found that the modes of vibration can be successfully identified by impulse tests, with the force pulse generated either by operation of the machine or by means of a hand held hammer.
Hunting Stability of the Three Axle Locomotive Truck
Authors: Rinehart R. E.
Published: November 2010

The hunting stability of the 3-axle locomotive truck is evaluated, using a linear eleven degree of freedom model. Predictions from the model are validated with test data, and the effects of wheel profile and secondary suspension damping on hunting stability are shown.
Textile Machinery Research 1948–1978
Authors: Mayer M.
Published: November 2010

Major developments in textile processing machinery in the United States over the last thirty years resulting from organized research are described and discussed. It is shown how events and economic trends in the world picture during this period have influenced many of the developments. A brief look into the future of textile machinery is also presented.
Measurement of Fiber Diameter and Diameter Distribution by Image Analysis
Authors: Barker R. L. , Lyons D. W.
Published: November 2010

An optical scanning procedure is described for scanning a fiber and measuring the projected diameter of the fiber at different points along its length. A method of analysis is discussed for obtaining from these measurements the average optical diameter or ribbon width of the fiber. By using the image analyzer to scan an array of fibers, the range or distribution of fiber sizes is defined for various different samples of fiber. These data are discussed as the distribution statistics of the different samples of fiber are analyzed and compared.
A Microprocessor Controlled Twist Drill Grinder for Automated Drill Production
Authors: Fugelso M. A. , Wu S. M.
Published: November 2010

The presently available twist drill grinding machines evolved over a long period of time. They are a product of engineering ingenuity through trial and error. A recently developed mathematical model of twist drill geometry has made it possible to design rationally and to construct a geometrically simple drill grinding machine which provides for the separate and precise specification and adjustment of the important geometry parameters. The machine grinds a conical drill point specified by the four parameters of the model. The conical drill point model can be used to approximate the geometry of hyperboloidal and ellipsoidal drills, and these drills may also be ground on this machine. A microprocessor is used to control the drill grinder. It does the calculations required to convert the drill specifications into the proper positions and movements. It then controls the motion of the machine axes to initiate and complete the grinding process. The result is a machine that is simple mechanically and able to produce a variety of drill points to predetermined specifications.
On the Mechanism of Chip Breaking
Authors: Kaldor S. , Ber A. , Lenz E.
Published: November 2010

During metal cutting while products are being manufactured, the access material is removed in the form of chips. These chips are obtained in various shapes which depend on cutting conditions, type of workpiece material machined, grade of the tool, geometry of cutting, etc. While brittle materials are being machined, the chips are segmental and disintegrating during the chip formation process. Consequently, these chips cause no difficulties. The problem exists when ductile materials are machined and one may observe the following chip forms: I—Long chips—(two dimensional and oblique type); II—Helical chips—(two dimensional and oblique type). These chips were classified by their influence on production operation. Based upon the natural crater developed during the cutting operation a chip breaker groove was introduced. These grooves are pressed into the insert during its manufacturing. It appears that the configuration of the groove has a crucial influence on the range of cutting conditions in which adequate breaking will occur. The presented paper deals with the different machinisms of chip breaking while machining with groove type chip breakers. Tests were carried out to establish the influence of the various parameters, taking part in the cutting operation, on the chip breaking process.
Reliability Analysis of Parallel Manufacturing Systems with Two Machines
Authors: Hitomi K. , Nakajima M. , Takahashi N.
Published: November 2010

A stochastic mathematical model was built and analyzed by using the reliability theory for a manufacturing system in which two machines are arranged in parallel. Under the condition that the system is required to be operated at a constant rate of production, the variation of reliability and failure rate of cutting tools with the lapse of time were investigated, using the stress-strength model in failure physics. A time interval of tool replacement in the continuous operation and a time to failure for a manufacturing system which is composed of two lathes were also investigated.
Computer Simulation of Nonlinear Thermoelastic Behavior of a Joint in Machine Tool Structure and its Effect on Thermal Deformation
Authors: Attia M. H. , Kops L.
Published: November 2010

Analysis of a computer simulated case study of the nonlinear thermoelastic behavior of the joint between the column and the knee in a milling machine is presented. Significance of this behavior on the thermal deformation of contacting structural elements is evaluated. Computer simulation is performed by applying the approach based on recognition of interactions taking place at the joint. Through successive iterations, a convergence to the state of equilibrium is reached. Convergence is verified on a simplified model. The results indicate the significance of considering the behavior of the joint in predicting the thermal deformation, as the effect of this behavior extends throughout the structural elements. For the case under study, deformation of the structure differs noticeably from that without considering interactions at the joint. Distribution of the contact pressure, thermal contact conductance and heat flux along the joint indicate high degree of nonuniformity, which is responsible for the effect the joint has on the thermal deformation. Convergence to the state of equilibrium is reached in an oscillatory manner, as shown by the deformation of the knee. The simulated case is treated under the steady state conditions, however the approach can be extended to the transient state as well.
Drop-Size Distributions of Bingham Liquid (PAINT) Sprays Produced by Fan-Jet Pressure Nozzles
Authors: Janna W. S. , John J. E. A.
Published: November 2010

The drop-size distribution of Bingham liquid sprays was determined by experimentation. Three different highly viscous paints were sprayed with fan-jet airless spray nozzles at pressure ranging from 5 170 to 18 200 kPa. A collection device was constructed to capture a spray sample on microscope slides. Measurement of flattened droplet diameters with a microscope yielded drop-size distribution curves of accumulated volume per cent versus volume median diameter. It was postulated that the wall shear stress existing at the exit plane of the nozzle initiated liquid atomization. A logarithmic correlation was found between shear stress and volume median diameter.
Experimental Investigation of Electric Discharge Machining by Radioactive Tracers
Authors: Winograd Y. , Almagor M.
Published: November 2010

The technique of radioactive tracers was applied to the investigation of single discharge in electric discharge machining. The total amount of material eroded from one of the electrodes, as a result of one discharge, as well as its fraction which plates the opposite electrode, were determined. The discharges were produced by a single pulse generator, capable of producing rectangular pulses of duration ranging from 25 to 1000 μsec, with a rise time less than 2.5 μsec, which was especially designed and built for the purpose of this research. For the Cu-Cu pair of electrodes investigated, it was found that the amount of plating can be up to 20 percent of the total erosion.
Extrapolation of Rupture Data for Type 304 (18Cr-10Ni), Grade 22 (2-1/4Cr-1Mo), and Grade 11 (1-1/4Cr-1/2Mo-3/4Si) Steels
Authors: Wilson D. J.
Published: November 2010

Methods for determining 100,000 hr rupture strengths for setting Code stresses were evaluated critically. Using available data for Type 304, Grade 22, and Grade 11 steels, techniques were examined for maximizing the quantity and accuracy of extrapolated strengths and for obtaining average and minimum strength-temperature trend curves.
The Effect of Reinforcements on the Slow Stable Tear and Catastrophic Failure of Thin Metal Sheet
Authors: Creager M. , Liu A. F.
Published: November 2010

To determine the role of the reinforcement on the mechanics of crack arrest and residual strength of reinforced flat panels, both analytical and experimental work was conducted. Fracture tests were conducted on precracked panels containing crack stoppers made of four different alloys. A computer program was developed which computes the crack tip stress intensity factor for cracked reinforced panels. The effects of yielding of the straps and of the rivets were taken into account. Utilizing a failure criterion based on the concept of the material crack growth resistance curve in conjunction with the computed crack tip stress intensity curve, a failure analysis can predict the residual strength of precracked reinforced flat panels. Comparisons between predicted failure loads and experimental test results for panels with a wide variety of reinforcement materials were within 10 percent.
Notch Sensitivity, Mechanical, and Microstructural Characteristics of TD-NiCr at Elevated Temperatures
Authors: Wilson D. J. , Ferrari A.
Published: November 2010

Tensile and creep-rupture tests were conducted for smooth and sharp edge-notched specimens of 0.015-in. (0.38 mm) thick TD-NiCr sheet at 1000 to 1800 deg F (538–982 deg C). The dislocation mechanisms operative were in good agreement with theoretical concepts. Time-dependent notch sensitivity was not observed. The notched specimen behavior correlated with the same mechanical characteristics and microstructural features as previously established for Waspaloy and Inconel 718 which are strengthened by coherent precipitates.
Forces Produced by Ground Contact Rotational Orthotic Devices
Authors: Rodenberger C. A.
Published: November 2010

The correction of lower extremity rotational deformities, such as tibial and femoral torsion, requires the application of derotational forces. One method of applying such rotational forces during ambulation is through the use of ground contact rotational orthotic devices. Two devices were tested. One device uses parallel rows of slanted rubber ribs and the other has slanted rubber ribs located in a circular array to produce rotational forces when the device strikes the ground during normal walking. It was found that the parallel rowed rib produced a rotation of 5.5 deg during walking and when rotation was prevented, torsional force produced by the device was approximately 20 in-lb. The circular array of ribs produced a complete rotation of 18 deg. When rotation was prevented, the heel produced 21.5 in-lb of torsion. The possible resisting torsion of a normal adult male was determined to be 11 in-lb at an 80 lb applied weight. Therefore it is concluded that the ground contact rotational devices will either provide rotation to the extent of the applied load or will apply torsional force greater than that encountered by normal leg structure.
A Fracture Theory for Brittle Anisotropic Materials
Authors: Priddy T. G.
Published: November 2010

This paper outlines the development of a general macroscopic failure theory. The result is a relatively simple cubic equation where interaction coefficients for tension-tension and compression-compression strengths may be defined separately. Approximations for biaxial and triaxial normal stress interactions are included to reduce the number of experimental data to nine for brittle three-dimensionally orthotropic materials and to two for brittle isotropic materials. A necessary condition that the theory closely describe brittle isotropic material strength is satisfied for a comprehensive set of cast iron biaxial strength data. The surface is graphically illustrated for various materials.
A New Parameter for the Hysteretic Stress-Strain Behavior of Metals
Authors: Jhansale H. R.
Published: November 2010

Analysis of transient and steady state stress-strain hysteresis behavior of several structural metals reveals a new parameter, defined as the “Yield Range Increment”, which uniquely denotes the various transient phenomena including cyclic hardening, softening, relaxation, and creep and the steady state cyclic stress-strain behavior. All transient and steady state hysteresis branches of a given material appear to be identical in shape, after their Yield Range Increments, which are suitable portions of the initial “elastic” parts, are deleted. A mathematical model incorporating the Yield Range Increment is proposed. With the determination of the functional relationship between the newly proposed parameter and the several input variables of cyclic loading, this approach should lead to a unified approach for describing the cyclic stress-strain response of materials.
Warm and Cold Heading of Stainless Steel
Authors: Tevaarwerk J. L. , Sowerby R. , Plumtree A.
Published: November 2010

A series of warm and cold heading tests ranging from room temperature to 400 deg C have been conducted on 305 and copper bearing 302 stainless steel wires as well as 0.2 percent C steel wire using a fully instrumented double blow Waterbury-Farrel machine heading 100 blanks per minute. Total and frictional forces developed during the first blow using a variety of lubricants, together with the second blow loads have been recorded. The effectiveness of the different lubricants employed was examined. The optimum blank temperature for warm heading stainless steel is in the range 200 to 400 deg C where the punch loads are reduced about 25/30 percent, compared to cold heading. Within this temperature range the friction coefficient for the copper coated stainless steel possessing a stearate film on the surface remains relatively low (μ ∼ 0.01/0.02). Reduced punch loads are shown to effect an increase in punch life. For all temperatures the heading loads for the copper bearing 302 stainless steel were lower than for 305 stainless steel. Both these materials exhibit a weak dynamic strain aging effect compared with plain carbon steel. In fact the heading loads were higher between 300 deg and 400 deg C for the plain carbon steel. At room temperature components made from both copper bearing 302 stainless steel and 305 stainless steel possessed fewer shear cracks when employing the former material and this effect is attributed to a lower strain hardening rate.
A Consideration on Limits of Cold Working in Nuclear Construction
Authors: Moen R. A. , Smith G. V.
Published: November 2010

Cold working of metals affects the mechanical properties of those metals. These effects are particularly important in the design, analysis and subsequent performance of materials used in elevated temperature nuclear construction. This paper provides an assessment of the effects of cold working on the time independent and time dependent mechanical properties of the materials most commonly encountered in liquid metal fast breeder reactors. The paper suggests specific reductions, as a function of time, temperature and cold work level, for those properties adversely affected. The final objective of this paper is to provide an assessment of the manner in which the Code now addresses fabrication effects and how it might make those assessments in the future.
“In Vivo” Determination of Macroscopic Biological Material Properties
Authors: Garner E. R. , Blackketter D. O.
Published: November 2010

This paper describes an experimental-analytical technique for determining the in-vivo macroscopic biological material properties of the human forearm. The technique utilizes the experimentally determined steady-state response of the forearm to a harmonic excitation in the 100 to 1000 Hertz band and a non-symmetric three-dimensional finite element model of the forearm. The “in-vivo macroscopic material properties” were determined by adjusting the material properties of the finite element model until there was a minimum of difference between the response of the finite element and the response found experimentally in the 100 to 1000 Hertz band. Both the soft tissues and the hard tissues were modeled as viscoelastic materials.
Failure in Two Fire Extinguishers
Authors: Smith C. O.
Published: November 2010

Failures of two fire extinguishers are examined in this paper detailing circumstances, laboratory examination, and analysis of failure. Both failures resulted in serious injury to the individual handling the extinguisher at time of failure. Both failures could have been prevented by implementation of well-known technology.
Investigation of the Plastic Properties of Certain Ferrous and Nonferrous Materials at High Temperature
Authors: Kaftanog˘lu B. , Sivaci K.
Published: November 2010

Plastic properties of certain carbon steels, brasses, copper, and aluminum are determined between room and recyrstallization temperatures. The investigations are carried out using the tension test conducted in a specially constructed furnace. Equivalent-stress, equivalent-strain curves and plastic anisotropy parameters are obtained. The equivalent-stress, equivalent-strain curves are then fitted to an empirical equation σ¯ = A(B + ε¯)n by a computer program employing a numerical gradient method. The results show that equivalent stress decreases as the temperature increases, and it increases as the strain-rate increases. Materials obtained as round bars show very little plastic anisotropy in their transverse planes whereas materials in the form of sheets have pronounced anisotropy. Plastic anisotropy decreases as temperature increases. The results obtained and techniques used may prove to be useful for designers of metal forming equipments, and researchers in the area of plasticity.
Erosion of Powder Metallurgy Aluminum Alloys by Hot Propellant Gases
Authors: Alkidas A. C. , Varney A. M. , Shrader R. E. , Morris S. O. , Summerfield M.
Published: November 2010

Experimental results are presented on the erosion of PMA (Powder Metallurgy Aluminum) alloys by a pulse of high pressure and high temperature combustible gases. The PMA alloys have been found to exhibit superior erosion resistance characteristics than wrought aluminum alloys. Of the PMA alloys tested, SAP materials (Sintered Aluminum Powder) were shown to be the best. The primary mechanism of the erosion of PMA alloys was found to be the melt and wipe off process. Combustion of aluminum that is responsible for the catastrophic erosion of wrought aluminum alloys was inhibited in PMA tests. Several hypotheses that explain erosion resistance of the PMA alloys have been postulated.
Fatigue Crack Growth of Bondline Cracks in Structural Bonded Joints
Authors: Brussat T. R. , Chiu S. T.
Published: November 2010

Adhesive bondline crack growth data are presented from fatigue tests of structural bonded single-lap joints with initial bondline flaws. Crack growth was successfully monitored both ultrasonically and by a compliance technique. A fracture mechanics analysis estimate of bondline crack growth rates in these tests is described, and the estimated rates are compared to the actual monitored crack growth rates.
Quarter Elliptical Cracks Emanating From Holes in Plates
Authors: Kullgren T. E. , Smith F. W. , Ganong G. P.
Published: November 2010

The finite element-alternating method, a linear elastic solution technique, is refined and applied to problems of quarter-elliptical cracks in irregular bodies. The method involves the iterative superposition of a finite element solution for stresses in an unflawed body and an analytic solution for stresses in an infinite solid containing a flat elliptical crack. Mode-one stress intensity factors are presented along the periphery of quarter-elliptical cracks emanating from open fastener holes in flat plates. Results are shown for a variety of crack geometries and two hole-diameter to plate-thickness ratios. Comparisons are made with experimental results of other authors.
Fracture Mechanics Parameters for a 5083-0 Aluminum Alloy at Low Temperatures
Authors: Tobler R. L. , Reed R. P.
Published: November 2010

The fatigue crack growth and fracture resistance of a 5083-0 aluminum alloy plate were investigated at four temperatures in the ambient-to-cryogenic range—295, 111, 76, and 4 K. J-integral test methods were applied using compact specimens 3.17 cm thick, and the value of J required to initiate crack extension (JIc) is reported as an index of fracture toughness. The fracture toughness was orientation dependent, with anisotropy accounting for JIc variations of up to a factor of 2. For specimens having fracture planes parallel to the rolling direction, JIc increases progressively from 9 to 25 kJm−2 as temperature decreases between 295 and 4 K. In contrast, the fatigue crack growth rates (da/dN) are insensitive to specimen orientation. The fatigue crack growth rates at cryogenic temperatures are up to 10 times lower than in air at room temperature, but are virtually constant between 111 and 4 K.
The Technical Evaluation of a Large Scale Solar Distillation Plant
Authors: Lawand T. A.
Published: November 2010

A theoretical evaluation of the heat and mass transfer interchange in an air-inflated solar still has been studied. Experimental verification tests have been carried out and the results compared with theoretical predictions. The percentage of unaccounted heat losses on the overall balance was under three percent for most tests. Continued modification of the theory is necessary in order to account for variations in some of the internal balances.
Measurement of Flame Temperature and Emittance in Gas Turbine Combustors
Authors: Hill W. E. , Dibelius N. R.
Published: November 2010

The radiation heat load assumes an important role in gas turbine life and performance as firing temperatures and pressures are increased. This first phase of a program for assessing radiant heat loading was mainly concerned with devising measurement techniques. An experimental method for measuring the temperature of luminous flames with a two-color pyrometer and radiant intensity by means of a total radiation pyrometer is described. Emittance data from two combustion liner configurations is included for chamber pressures of from 2 to 7.5 atmospheres over the turbine inlet temperature range of 900 to 1950 deg F.
Theoretical and Experimental Determination of Pressure Losses in a Single-Stage Axial Flow Compressor
Authors: Le Bot Y. , Paulon J. , Belaygue P.
Published: November 2010

A single, isolated, test axial compressor rotor in a constant section annular duct is used for determination of off-design pressure losses. The results obtained are interpreted by means of loss coefficients and description of the flow field is deduced from a simplified actuator theory that takes into account pressure losses. Rotor stall limit is interpreted as that limit mass flow rate for which no continuous solution of the equations can be obtained. Unstable operations that take place for mass flow rates smaller than the stall limit are shown to be either rotating stall or wall separation, according to the shape of the downstream pressure profile. Experiments on the rotor confirm validity of these assumptions.
Semiempirical Criterion of Erosion Threat in Modern Steam Turbines
Authors: Krzyz˙anowski J. , Weigle B. , Severin H.
Published: November 2010

A parametric relationship is developed for the degree of erosion to be expected in a low-pressure steam turbine stage operating with wet steam. This relationship involves geometrical parameters of blading, thermodynamic parameters of stage flow, properties of blade material, stable drop size, and impact velocity of attacking stream of droplets, the resulting impact pressure, and service time of the turbine. Although not all of the parameters are exactly known or calculable, most of the unknowns can be assumed to remain approximately equal for typical modern turbines. Therefore, a two-dimensional field can be specified with impact pressure as one coordinate and a simplified calculable parametric expression as the other coordinate. On such a field one should be able to plot lines of constant erosion severity, which has been done with the help of field service measurements from a large collection of steam turbines. The resulting chart provides a semi-empirical tool for the prediction of erosion in other turbines.
On the Behavior of Uniform Shear Flow in Diffusers and Its Effects on Diffuser Performance
Authors: Masuda S. , Ariga I. , Watanabe I.
Published: November 2010

Behavior of uniform shear flow in rectangular parallel-walled diffusers and its effects on the diffuser performance were investigated both experimentally and theoretically. Velocity and static pressure distributions were measured varying the total divergence angle from 0 deg to 20 deg and the free stream velocity gradient at the inlet of the diffuser from 01/sec to 10001/sec. It became clear that a decay of velocity profile nonuniformity occurred and it affected the static pressure distribution seriously. Inviscid analysis was also performed, but its results did not always agree with experiment because of turbulence.
A Blade Theory of an Impeller With an Arbitrary Surface of Revolution
Authors: Senoo Yasutoshi , Nakase Yoshiyuki
Published: November 2010

In this report a method of analyzing subsonic inviscid flow between blades on a stream surface of revolution of a turbomachine, which may be an axial, a radial, or a mixed-flow type, is presented. There may be a change in thickness of stream surface of revolution in the through flow direction. The stream surface of revolution is mapped onto a plane. In this picture plane the influence of rotation of the system is not always represented by uniformly distributed vorticity. Instead, the distribution of vorticity varies with radius. For the calculation of velocity distribution in the picture plane, an available rotating annular cascade theory is modified so that the variation of vorticity with respect to radius is properly considered. Numerical examples for a mixed flow type compressor rotor are included.
A Fiber Optics Probe for Measurements in Emitting-Absorbing Flames
Authors: Sakkal F. , Heberlein J. , Pfender E.
Published: November 2010

In this paper, a fiber optics probe is described which is designed for diagnostics in emitting-absorbing flames. The probe is swept with constant speed through the flame to be investigated, and the spectrally resolved light signal received by the probe is recorded. As a sensitive check for the applicability of such a probe as a diagnostic tool, the curves of growth of the sodium resonance lines are measured, using a laminar temperature-shielded, sodium-seeded propane gas flame. The results demonstrate the usefulness of this probe for applications in flames containing solid particles.
Modelling of Gas Turbine Combustors; Considerations of Combustion Efficiency and Stability
Authors: Odgers J. , Carrier C.
Published: November 2010

The stability and combustion efficiency performance of gas turbine combustion chambers is examined with relation to correlation groups derived from a reaction rate equation obtained in earlier work (ASME Paper No. 71-WA/GT5). Five different combustion chambers were used to assess the parameters and they represented both tubular and annular chambers. Four of the combustors were fitted with pressure fuel atomizers and one was a vaporizer chamber. The chambers were operated over a wide range of inlet temperatures and pressures, as well as air/fuel ratios. The overall combustion efficiency of the chambers is shown to be described by the following equations: log log 100/η = A log mf/V′Pn + Bφ + C (weak mixtures in the combustion zone), and log log 100/η = A log mf/V′Pn + B/φ + D (rich mixtures in the combustion zone). The relevance of these equations is also considered. An examination is made of conditions within the recirculation zone, but because of the scarcity of data, no firm conclusions may be drawn.