bluuebunny/crossref_metadata_2025 huggingface dataset:
Integration of New Sensors Into Space Vehicles
Authors: Medelius Pedro J. , Bartine Dave
Published: August 2008

For the successful integration of new sensors into space vehicles, it is necessary to establish early in the project a close and interactive between the technology developer and the end user. The problem to be solved and prospective solutions required from the technology developer should be clearly identified and well defined to demonstrate that the proposed technology works satisfactorily in the relevant environment and that it presents no danger or interference to existing systems. The technology provider has to remain involved with the user through installation, acceptance testing, and acclimation of the new technology. The product developer and end user must jointly perform the following functions: • Develop a detailed set of requirements: performance, physical, environmental, safety, reliability, and maintainability. • Establish the qualification process to certify the product. • Define the documentation requirements for the qualification process. • Establish a quality control process to monitor the design, fabrication, testing, and integration of the product into the vehicle or the ground support system. It is important that the performance requirements established by the user be well defined before any potential solution to a problem is considered viable. The successful integration of micro- and nanotechnology into space vehicles requires a coordinated effort throughout the design, development, installation, and integration processes. The selection of materials for sensors and associated instrumentation is critical because certain materials can cause hazards in the space environment that are not apparent in the ground environment. Materials should be selected early, and their use approved by the user. The safety community should be involved early in the design process, even during the conceptual design phase. Certification and safety problems that are often found late in the design cycle can be avoided easily and less expensively if they are addressed early in the process. Flight and ground operations personnel should also contribute to the design process since they are the people who will be installing sensors and instrumentation, as well as operating the systems. They understand the vehicle and support systems that will be required to support the installation and operation of new systems.
Application of MEMS Technology to a Lightwave Antenna for Communication in Space and Aeronautics
Authors: Munemasa Yasushi , Sano Masatoshi , Mita Makoto , Takano Tadashi
Published: August 2008

This paper reports a novel MEMS (Micro Electro Mechanical Systems) lightwave (optical) antenna as a telecommunication device in space and aeronautics. The high performance antenna at light wave frequency requires optimal curved surfaces and high mechanical precision to acquire high aperture efficiency. We have developed a novel micro lightwave antenna by applying MEMS (Micro Electro Mechanical Systems) technology. The antenna of transparent type (lens) is fabricated as a trial antenna, which has a 3-level step structure with diameter of 4 mm, to show the advantage of the antenna. The characteristics of the fabricated antenna have been measured. The measurement results of gain and power radiation pattern are in agreement with simulation result.
Standard MEMS Capacitive Accelerometers for Harsh Environment
Authors: Stauffer Jean-Michel
Published: August 2008

Many markets have already successfully introduced MEMS based products in a very large panel of applications. When looking carefully at the market implantation, it is very interesting to see that benefits of this technology go well beyond the obvious size advantage. Size and weight but also performance, power consumption, parallel manufacturing capability and cost or reliability are common arguments in favour of this family of products. Nowadays, standard MEMS technologies give access to a broad range of unexpected new applications opportunities by always pushing the products at their limits, mainly in term of environmental constraints. Great potentials have been demonstrated and have engendered development alliance to improve the performances of the products in so called harsh environments: Imagine the utilization of an accelerometer in oil and gas prospecting applications. They must provide precise measurements in a very high or cold temperature environment, in a world of extreme vibrations and must potentially endure very high shocks. The objective of this presentation is to review actual results and current limitations when using MEMS sensors in harsh environments (temperature, shock, vibration, environment, security). The conjunction of material and technologies (standard Si, SiC or SOI), advanced micromachining techniques and advanced assembly techniques are the key to provide robust sensors. Within a large portfolio of examples, the following applications will be presented and developed in more details: • Accelerometers surviving shock levels up to 20’000g with minimum impact on specification. • Very robust MEMS sensors used between −120°C and +180°C. MEMS sensors in harsh environment are already a reality and various products are already available off the shelf and supplied with high volume opportunities.
Aerospace Micro-Nano-Technology High Technology-Readiness-Level Acceleration Using Directed Patent Information Analysis
Authors: Kapsalas George
Published: August 2008

Micro-Nano-technology (MNT) development efforts for aerospace applications face significant challenges in rapidly and efficiently transitioning aerospace MNT development from the low technology-readiness-level (TRL) stage found primarily in the research and development community to a mid and high TRL within the systems developer community. This paper explores and highlights some opportunities for more efficiently linking these two TRL stages using directed international patent information analysis as a core method. Possible injection of systematic methodologies of patent information analysis at certain points of a project development flow are suggested. Practical case examples in aerospace MNT suggest that such analysis may have significant potential to qualitatively enhance frameworks for accelerated transitioning of aerospace MNT development to the high TRL stage and to commercialization.
Development of MEMS-Based Components and Subsystems for Spacecraft Propulsion
Authors: Rangsten Pelle , Gro¨nland Tor-Arne , Johansson Ha˚kan , Jonsson Kerstin , Bejhed Johan , Carlqvist Mattias
Published: August 2008

Development of a MEMS-based (Micro Electro Mechanical System) components and subsystems has been pursued at Uppsala University, Sweden since 1997. Since 2005, the continued development towards the first flight the subject MEMS products onboard a satellite in 2008 is done within the frame of NanoSpace — a company dedicated to MEMS-based products for space. Currently, two major efforts to develop MEMS-based propulsion products are ongoing. First, NanoSpace is developing a miniaturized cold gas propulsion system. The major challenge in this effort is to develop the thruster module containing four individual thrusters with the capability to deliver proportional, low noise thrust in the micro- to milli-Newton range. The thruster pod even includes valves, filters, pressure- and temperature sensors and heaters. In a future step, even control electronics and a CAN interface will be included in the thrusters pod which has the size of a golf ball and a weight of about 100 grams. A prototype of this miniaturized cold gas propulsion will be flight tested onboard the PRISMA satellite. PRISMA is an international technology demonstration program with focus on rendezvous and formation flying. It is a two satellite LEO mission with a launch scheduled to September 2008. The other major development effort underway is a MEMS-based Xenon flow control system intended for electrical propulsion systems. Using MEMS technology, a Xenon feed system including an micro isolation valve, pressure regulator, and a number of parallel flow control modules can be built with significantly reduced size and mass compared to existing systems based on conventional technology. NanoSpace is a Swedish company with the goal to be a component and subsystem supplier of MEMS-based products to space industry, based on own research and development and intellectual property rights.
MEMS Inertial Technology for Aerospace Applications
Authors: Lautenschlager Eric J.
Published: August 2008

The aerospace industry has guidance, navigation, and control needs which make use of a number of inertial technology systems. MEMS based solutions can offer several advantages over conventional technologies and are being developed for a wide range of applications. This paper will review the broad inertial applications that exist for the aerospace industry, identify some of the current non-MEMS technologies used to meet those needs, and then discuss what advantages MEMS based solutions can provide. This will be followed by a high level explanation of the general operating principles of a MEMS gyroscope, as well as identification of key performance metrics and error terms that are used for sensor evaluation. Finally, there will be a discussion of some basic design considerations, a review of the current state of the art for performance, and future goals and directions for inertial MEMS technologies. NOTICE: High performance inertial technology is subject to restrictions imposed by the International Traffic in Arms Regulations (ITARS), and Export Administration Regulations (EAR). The use of these technologies, or information pertaining to these technologies, may be restricted from foreign nationals of the United States.
Industrial Verification of Piezo Motors on a CubeSat Based Verification Platform
Authors: Czech Manuel , Walter Ulrich
Published: August 2008

Due to the classification of technologies in NASA’s and ESA’s technology readiness levels, newly developed components have to be space proven before they can be utilized in space missions. This space prove can be adduced by sending these technologies to orbit either as experiment on a piggyback flight or a dedicated mission. Over the last years the size of technologies and satellites has shifted to much smaller sizes. In this paper, the possibility of industrial verification of MEMS (Micro Electro Mechanical System) applications using dedicated pico-satellite missions is examined. Based on the CubeSat concept, a technology verification platform can be realized for verification of not only pico-satellite components, but also of components of complex systems and missions. Therefore a platform fulfilling the requirements for such industrial verification of components named MOVE (Munich Orbital Verification Experiment) is developed at the Institute of Astronautics (LRT). This platform enables professional verification of MEMS technology and techniques at overall mission costs of less than 100k€. As a first application of this approach, a mission called π-MOVE (π for piezo) will verify piezo motors on the developed platform. These piezo motors are representative for components of complex systems, as this motor concept is considered to be key technology for future segmented mirror telescope missions. In the mission design process for this platform, strong emphasis is put on the robustness of the design, low complexity and realizability within the institute’s environment. The advantages through access to both university and industry resources will be taken. The feasibility of professional technology verification is highly dependent on the test plans, which are developed in cooperation with the experienced industrial partners.
The Brazilian Initiative in MNT for Aerospace Applications
Authors: Mateus Carlos Fernando Rondina , DaSilva Andre´ Ce´sar
Published: August 2008

The Brazilian Nanotechnology Program, organized by the Ministry of Science and Technology in 2001, has created grants for several collaboration networks, new laboratories, and special projects, from materials to biotechnology. It is accepted that nanotechnology has an enormous potential to impact the aerospace industry, mainly because of the increased functionality and reduction in weight, size and energy consumption. On Aerospace Science and Technology, Brazil has been a strong player. Embraer is one of the largest aircraft manufacturers in the world and has significant presence in commercial, defense, and executive aviation. Brazil is also one of the few nations around the world with a complete space program, which includes families of satellites, sounding rockets, launching vehicles, launching sites close to the Equator, and partnership in the International Space Station. Therefore, the country is well placed to move forward and incorporate MNT into the aerospace industry. The Brazilian initiative in MNT for Aerospace Applications has arisen in 2004, aiming to direct the effort and to foster the aerospace industry. The first workshop of MNT for Aerospace Applications – “Nano-Aeroespacial 2004” took place in October 2004. The “Nano-Aeroespacial 2006” meeting is scheduled to happen on October 2006. The Brazilian Roadmap on MNT for Aerospace Applications has already completed two phases and the third and last one is scheduled to happen on May 2006. The results of this roadmap will be communicated at the conference time.
MEMS Reliability Assessment Methodology for Aerospace Applications
Authors: Chauveau P. , Blondy P. , Pothier A. , Crunteanu A. , Fargeot S.
Published: August 2008

This paper presents a new dynamic and parametric model of a capacitive micro-electromechanical switch electro-statically actuated. It is built of elementary electrical equivalent-circuit blocks constructed of voltage controlled current sources. The model describes the nonlinear mechanical behaviour of the membrane movement, which allows the computation of the bridge capacitance. It can be inserted as a model to perform simulations as parasitic effects on MEMS structures. All switch parameters such as dimensions and material properties are adjustable.
Outline of Overall Aircraft Imposed Requirements on Airframe Enhancements by Nanotechnologies and Resulting Opportunities
Authors: Woelcken Piet , Bockenheimer Clemens , Speckmann Holger , Entelman Wolfgang
Published: August 2008

Ongoing development efforts in all stages of technological readiness have encouraged this paper which aims at outlining the predominant requirements which an aircraft structure does and will pose to new and emerging technologies. Particular emphasis is placed on the vast field of nanotechnologies. By outlining the broad requirements of an aircraft structure on new technologies, example studies and public long term scenarios, this paper aims at providing a broad guide to potential, new applications of micro-and nano-technology for structural aircraft applications.
Use of MEMS Sensors to Design a Life Consumption Monitoring System for Electronics
Authors: Rouet Vincent , Foucher Bruno
Published: August 2008

To improve the reliability, the design and the maintenance of electronic systems, the knowledge of the operational environment in which these systems operate is essential. HUMS (Health and Usage Monitoring System) are specialised in environmental monitoring and provide operating life status according to the experienced loads. Nevertheless, their major drawbacks, which limit their use, come from their size and their ability to provide relevant information for health assessment. Usually performed by a ground-based software, the environmental data are analysed off-board periodically, after regular HUMS downloads. However, the speed needed for failure prediction calculation from the stress monitored to the warning reported is essential to prevent ongoing operation of an electronic system on the way to failure. This paper presents a smart integrated electronic system embedding MEMS sensors for in-situ health assessment associated to the experienced loads. This system uses advanced algorithms processing the measurements for immediate Prognostic Health Monitoring (PHM), based on the Physics of Failure for real-time life consumption prediction of electronic systems.
Assessment of Local Decreases in Wall Thickness at the Connection Straight-Pipe to Bend
Authors: Kauer Robert , Holzer Wieland
Published: August 2008

Welds are ground during manufacturing to free them from offset edges and notches and thus to obtain a more favorable stress distribution. Apart from the above, welds are also ground to prepare them for and improve the conditions of in-service testing and inspection. The grinding of welds may result in a local decrease in wall thickness, so that there may be local deviations from the required minimum wall thickness. In order to fulfill the task of evaluating the strength of such material-loss regions, we have determined appropriate stress concentration factors for typical wall-thickness deviations and various wall-thickness/diameter ratios, which enable us to assess quickly and, if necessary, directly after the on-site measurement of wall thickness, whether a detected deviation from the minimum value is permissible. To be able to evaluate deviations from minimum wall thickness, especially in welds that form a connection to bends, we have determined stress indices for the beginning and the end of bends for common pipe bend dimensions and various bend angles. Compared with the maximum stress indices commonly used in piping calculations for the crown of the bend, the stress indices at the end of the bend are lower than those at the crown and can help to reduce unnecessary conservatism. In the paper, stress indices for various grinding geometries and for the beginning and the end of common bend shapes will be presented, as well as the method used to evaluate strength and the criteria pertaining to the tolerability of decreases in wall thickness.
An Experimental Study on the Evaluation of Failure Behavior of Pipe With Local Wall Thinning
Authors: Kim Jin Weon , Park Chi Yong
Published: August 2008

The pipe failure tests were performed using 102mm-Sch.80 carbon steel pipe with various simulated local wall thinning defects, in the present study, to investigate the failure behavior of pipe thinned by flow accelerated corrosion (FAC). The failure mode, load carrying capacity, and deformation ability were analyzed from the results of experiments conducted under loading conditions of 4-point bending and internal pressure. A failure mode of pipe with a defect depended on the magnitude of internal pressure and axial thinning length as well as stress type and thinning depth and circumferential angle. Also, the results indicated that the load carrying capacity and deformation ability were depended on stress state in the thinning region and dimensions of thinning defect. With increase in axial length of thinning area, for applying tensile stress to the thinning region, the dependence of load carrying capacity was determined by circumferential thinning angle, and the deformation ability was proportionally increased regardless of the circumferential angle. For applying compressive stress to thinning region, however, the load carrying capacity was decreased with increase in axial length of the thinned area. Also, the effect of internal pressure on failure behavior was characterized by failure mode of thinned pipe, and it promoted crack occurrence and mitigated a local buckling of the thinned area.
Thermal Mixing Points: A Thermomechanical Stress FEA Procedure
Authors: Seipp Trevor G. , Reichert Christopher
Published: August 2008

This paper outlines a procedure for calculating and evaluating the stresses in piping thermal mixing points, which combine process streams of significantly different temperatures. The temperatures and stresses in the pipe at the mixing point are calculated using 3-D finite element analysis. The temperature field calculations use a pipe flow heat transfer correlation. Once the temperature field is determined, it is used to calculate the thermal stresses. The stress results are calculated using the methodology of WRC-429 and compared to the allowable limits. The results of two sample mixing points are shown.
Finite Element Analysis for Local Creep of a Tube Coolant Piping System in Light Water Reactor Due to Local Heating Under Severe Accident Condition
Authors: Hagihara Seiya , Miyazaki Noriyuki
Published: August 2008

During severe accident of a light water reactor (LWR), reactor coolant piping would be damaged when the piping is subjected to high internal pressure and very high temperature due to heat transfer from high-temperature gas and decay heat from wall-deposited fission product (FP), both from degraded core. In such a case, high-temperature fast creep deformation could be the main cause for the pipe failure. For the evaluation of piping integrity during severe accidents, a method to predict such high-temperature fast creep deformation should be developed, using a creep constitutive equation considering tertiary creep behavior which has not been considered well in the pipe failure analyses. In this paper, a creep constitutive equation was developed, which is based on the Kachanov-Ravotnov isotropic damage rule considered the tertiary creep behavior. Japan Atomic Energy Research Institute (JAERI) creep tensile test data for nuclear-grade cold-drawn SUS316 material was used to determine coefficients of the developed constitutive equation. Using the developed constitutive equation, finite element analyses were performed for local creep deformation of coolant piping under two temperature conditions; uniform temperature and temperature gradient. The analyses results indicated the damage variable being integrated following the evolution of creep damage can indicate pipe wall internal damage condition quantitatively. The damage variable was confirmed further to be able to reproduce the observation in JAERI piping failure tests; pipe failure from the wall outside.
Stress Indices for Circumferential Fillet Welded and Socket Welded Joints
Authors: Wais Edward A. , Rodabaugh E. C. , Carter R.
Published: August 2008

This paper presents the results of an investigation of the Stress Indices for circumferential fillet welded or socket welded joints which are required for ASME Section III Class 1 systems. The history or background of the basis of the various indices is reviewed and summarized. New values for the indices are suggested based on new test data and analysis. These changes will result in a more accurate evaluation of circumferential fillet welded or socket welded joints.
Temperature Attenuation Along Pipe Support Stanchions
Authors: Basavaraju Chakrapani , Fox Ronald C.
Published: August 2008

High temperature steam lines in power plant piping systems are often supported by the use of pipe support stanchions welded to the steam pipe. The end of the pipe stanchion has a steel plate welded to it, which typically slides on rack steel. For vertical and guide supports, there could be considerable thermal movement in the lateral unrestrained directions, and could result in significant frictional loads. The associated frictional loads are given due consideration in piping local stress evaluations as well as in the design of pipe support structures. For some situations, it often becomes necessary to utilize a teflon-fluorogold type surface at the stanchion end plate in order to reduce the coefficient of friction and hence the frictional loads. The effectiveness of the teflon-fluorogold surface is dependent on the prevailing temperature at that surface. In situations where the stanchions on very high temperature steam lines arc relatively short, the temperature at the teflon surface of the stanchion plate could be high due to heat transfer from the steam line into the stanchion. This high temperature at the bottom surface of the stanchion plate may interfere with sliding and may eventually lead to unanticipated problems such as sticking, increase in the coefficient of friction, or unpredictable frictional behavior. In this paper, finite element analysis approach is utilized to perform heat transfer analysis and to obtain steady state temperature distribution due to decay or attenuation from the steam line surface along the stanchion. The temperature prevailing at the bottom plate surface of the stanchion is also evaluated and guidelines are provided for practical application of the results.
Structural Evaluation of a Piping System Subject to Thermal Stratification
Authors: Chattopadhyay Som
Published: August 2008

In this work methods have been presented to compute the primary plus secondary stresses as well as peak stresses caused by a stratified temperature profile produced by mixing of hot and cold fluids. The stratified temperature profile gives rise to a circumferential metal temperature gradient through the pipe. An analytical technique has been outlined to calculate the combined membrane plus bending stress intensities employing the circumferential temperature gradient across the pipe. The purpose of the effort is to address ASME Code compliance, recognizing that the piping code does not specifically address the circumferential temperature variation. The peak stresses due to a stratified temperature profile have been evaluated by employing a finite element procedure.
Seismic Design of Geothermal Pipeline Supports
Authors: Jonsdottir Fjola , Agustsson Gunnlaugur O. , Jonsson Magnus T.
Published: August 2008

Seismic loading is a critical factor in the structural design of piping systems for geothermal power plants in Iceland. It has been shown that the design of piping systems which is based on response spectrum static analysis can lead to overdesigned systems. The loading on the supports will be overestimated and, hence, the supports tend to be too stiff. This increased stiffness both increases the cost and reduces the quality of the seismic design. The systems response is highly dependent on the support stiffness. In this work, the design of a typical expansion loop with respect to seismic loading is discussed, with the goal being to minimize the loading from the ground acceleration. A typical pipe support is modelled, and its stiffness characteristics are evaluated and optimized. Finally, recommendations are made for improvements in pipeline support design.
Dynamic Pipe Stresses During Water Hammer: I — A Finite Element Approach
Authors: Leishear Robert A. , Young Edward F. , Rhodes Curtis A. , Alford Elisabeth M.
Published: August 2008

Water hammer is defined as a sudden increase in pipe pressure, which results in pressure waves that travel along the pipe at sonic velocities. In the wake of the pressure wave, dynamic stresses are created in the pipe wall, which contribute to pipe failures. A finite element analysis, computer program was used to determine the three dimensional dynamic stresses which result from pipe wall vibration at a distance from the end of a pipe, during a water hammer event. The analysis was used to model a moving shock wave in a pipe, using a step pressure wave. Both aluminum and steel were modeled for an 8 NPS pipe, using Abaqus®. For either material, the maximum stress was seen to be equal when damping was neglected. At the time the maximum stress occurred, the hoop stress was equivalent to twice the stress that would be expected if an equivalent static stress was applied to the inner wall of the pipe. At the same time, the radial stress was limited to the magnitude of the applied pressure, and the axial stress was equal to zero.
Investigation of Torsional Stress Intensification Factors and Stress Indices for Girth Butt Welds in Straight Pipe
Authors: Wais Edward A. , Rodabaugh E. C. , Carter R.
Published: August 2008

The basis for fatigue evaluation of ASME Section III Class 2, 3 and B31.1 piping is the girth butt weld where the Stress Intensification Factor (SIF) is defined to be 1.0. The SIFs for other components are based on comparison to the butt welds. This SIF of 1.0 for butt welds is based on extensive bending tests on carbon steel straight pipe which are reviewed and summarized in this study. The results of new test data, including torsional test data, are presented. The authors are unaware of any previous torsional tests on carbon steel straight pipe. This new data leads to suggested changes in the codes taking into account the directionality of the loading.
Application of Code Case N-597 for Local Thinning Assessment for Class 1 Piping
Authors: Iyer San , Kumar Rajnish
Published: August 2008

Process piping components such as elbows, bends and tees experience local wall thinning due to Flow Accelerated Corrosion (FAC). Fitness for service studies of the piping components that are affected by FAC for continued operation have gained importance in light of the plant life extension resulting in economic benefits for the operating utilities. ASME Code Case N-597 provides the guidelines for acceptance for continued service of Classes 2 and 3 piping components experiencing wall thinning during operation. However, for Class 1 systems, the Code Case recommends that the owner develop the methodology and criteria for the assessment of wall thinning. This paper establishes a criteria and methodology for the assessment of thinned Class 1 piping system components. The rules of NB-3221 and NB-3650 of ASME Boiler & Pressure Vessel Code (Ref.1) have been considered in establishing the criteria. The requirements of NB-3221 have been utilized for evaluating the adequacy of pressure design. After meeting this requirement, further evaluation of the piping with thinned area is carried out as per NB-3650 requirements for all loadings corresponding to design and service conditions. To illustrate the criteria and the methodology, an assessment of a sample problem of a locally thinned region in a pipe bend is provided in this paper. Finite element analysis and piping analysis are used for the assessment of the thinned region of the pipe bend. Loading considered includes pressure, deadweight, thermal transients and seismic effects.
Fatigue Life Prediction for Short Dents in Petroleum Pipelines
Authors: Rinehart Adam J. , Keating Peter B.
Published: August 2008

Pipeline dent fatigue behavior has been shown to be strongly dependent upon dent length and external force dent restraint characteristics. Full-scale laboratory tests have shown that short dents that are unrestrained by an external force typically experience fatigue cracking in the dent periphery outside of the dent contact region. A fatigue life prediction method for short dents is presented here. In order to assess method accuracy, predictions are made for cases in which fatigue life has been measured experimentally. The predictions account for both crack initiation life and crack propagation life. Stress concentration values used in the predictions are determined using finite element modelling on a case-by-case basis for comparison purposes. Appropriate crack initiation life estimates, stress intensity factor predictions, and crack propagation models are taken from existing literature. Predicted and measured fatigue lives are compared for the cases studied.
Dynamic Pipe Stresses During Water Hammer: II — A Vibration Analysis
Authors: Leishear Robert A.
Published: August 2008

Dynamic pipe stresses result from pipe vibrations created by water hammer. Current vibration theory was adapted to derive equations that describe the pipe stresses in a pipe wall which occur at a distance from the pipe end. These original equations describe the stresses in a pipe expansion mode, which is sometimes referred to as a breathing mode. The breathing mode was assumed to result from a moving shock wave traveling along the length of a pipe, and the shock was modeled using a step pressure wave, using the classic single degree of freedom vibration equations. Pipe stresses affected by both undamped and damped vibration were modeled. To model the stresses at a point on the pipe wall, vibration equations were linearized, and existing step response equations were applied to create stress models. Essentially, the linear vibration equations were converted into closed form solutions for the maximum pipe stresses. The vibration model was shown to be comparable to an undamped FEA stress model. The vibration model was then used to evaluate the effects of damping on dynamic pipe stresses.
A Dynamic Investigation of Piping Systems With a Bolted Flange
Authors: Semke William H. , Bibel George D. , Jerath Sukhvarsh , Gurav Sanjay B. , Webster Adam L.
Published: August 2008

The dynamic response of piping systems with a bolted flange is analyzed. Experimental and numerical analyses and results are presented and show excellent correlation. An overhanging piping system at various span lengths with a flange at mid-length is used. The testing configuration consists of a standard 2-in. (51 mm) schedule 40 steel pipe and an ANSI B16.5 class 300-pound flange. The presence of a spiral wound wire gasket and high strength flange bolts is also assessed. Included are multiple resonant frequencies and their respective mode shapes for various span lengths and gasket configurations. The experimental procedure utilizes an accelerometer to gather the dynamic response output of the piping system due to an impulse. The resonant frequencies are then determined using a Fast Fourier Transform (FFT) method. The numerical analysis is conducted using the commercial Finite Element (FE) code ANSYS®. Both methods take into account the complex interaction between the flange and gasket and their impact on the entire piping system. The dynamic effects of a bolted flange and gasket on a piping system are critical in their use and a summary of the results for a variety of configurations is presented.
Modeling Underground Pipe With Pipe Stress Analysis Program
Authors: Robleto Robert A.
Published: August 2008

The objective of this paper is the modeling of underground pipe in granular or sandy soil using a Pipe Stress Program for the evaluation of thermal, and pressure, to produce verifiable results. The use of a beam type pipe stress program to accurately perform stress analysis of underground piping can produce various results depending on the modeling. An updated presentation is available in B31.1 piping code with technical references, which gives some guidance in the use of pipe stress modeling. Modeling in a conservative way is difficult because what may be conservative to the underground piping may not be conservative at above ground transitions. An accurate methodology is required that produces verifiable results. Verification is accomplished by comparison with the B31.1 example problem and manual calculation using “Beam on Elastic Foundation”. Also discussed are the effects of SIF’s and flexibility factors used in above ground pipe and their application to underground piping. Ovalization of the piping is inhibited by the soil and the SIF’s and Flexibility factors are affected (pg 231) [1]. Recommendations are given in the conclusion for the accurate modeling using beam type pipe stress analysis programs.
Investigation of Design Method for Piping Systems to Prevent Acoustic Fatigue in Process Plants
Authors: Hayashi Itsuro , Hioki Teruo , Isobe Hiroshi
Published: August 2008

Piping systems for steam or gases with a pressure reducing device can cause acoustically induced vibration, resulting in material fatigue failure in process plant. Numerical investigation using sound-structure interaction analysis has been done to find the possible solution to reduce the dynamic stress level in the piping structure. The result shows that reinforcing of the pipe structure such as use of circumferential stiffener rings change the structural characteristic and the maximum stress in the pipe wall. Structural natural frequency is applied to evaluate both effectiveness of reinforcement of pipe structure and the effectiveness of the increase of pipe wall thickness.
Dynamic Pipe Stresses During Water Hammer: III — Complex Stress Relationships
Authors: Leishear Robert A.
Published: August 2008

Complex three-dimensional dynamic stresses occur in a pipe following a water hammer event. Equations from vibration theory were adapted for use to describe the dynamic stresses at any point along the pipe wall. Hoop, radial, and axial dynamic stress equations are presented to approximate the stresses at a point on the pipe wall. Dynamic stress equations for beams and other simple shapes are also considered. The dynamic pipe stresses are affected principally by the types of water hammer waves or fluid transients, by the wave impacts at elbows or tees, and by the reflections of the waves from these elbows or tees. The three fluid transients considered are a moving step pressure wave, a ramp pressure, and a moving pressure spike. Approximate techniques are presented for evaluating the effects on piping due to the impingement of these transients on an elbow. For an equivalent pressure in a long pipe, application of the step pressure created the largest stress increases of the three transients considered. The vibration equations also prompt a solution to reduce water hammer effects. To this end, slow closing valves are frequently employed. Vibration theory may be applied to quantify the stress reductions afforded by these valves. Pipe stress equations may be manipulated to reduce pipe stresses for a linearly increasing, or ramp, pressure wave traveling along the pipe.
Simulation of GRP Pipes Materials and Installations Parameters Experimentally and Using FEA
Authors: Ibrahim A. , El-Kousy R. , El-Mahllawi I. , Zaafarani N.
Published: August 2008

In this work, an analysis of GRP pipe installation is developed to study the interaction between a buried flexible pipe and surrounding supported soil. The results of the analysis are applied to computational model using FEA (Finite Element Analysis) to determine the pipe deformations at variable soil types around the pipe. Then, testing is done to compare FEA results with laboratory testing. The results obtained from simulation of deflection pattern for two different manufacturers are compared with ASTM 3839 D-88 for underground installation of flexible reinforced thermosetting resin pipes. The simulated model used two major manufacturers of buried pipes, allowing variation of soil stiffness and simulating realistic boundary conditions so in order that reliable deformations can be predicted. A semi-empirical methodology for the relationship for pipe in soil system for predication of the pipe and pipeline performance was developed in this work. The work developed a unified integrated approach for composite soil structure, which may be used by the designer, manufacturer and installers of GRP pipe.
Design of Ellipsoidal Heads Using Elastic-Plastic Finite Element Analysis
Authors: Florizone Donald J.
Published: August 2008

Traditional design techniques result in excess material being required for ellipsoidal heads. The 2001 ASME Boiler and Pressure Vessel Code Section VIII Division 1, UG-32D and Section VIII Division 2, AD-204 limit the minimum design thickness of the heads. ASME Boiler and Pressure Vessel Code Case 2261 provides alternate equations that enable thinner head design thickness. VIII-2 Appendix 3 and 4 methods potentially could be used to further optimize the head thickness. All the equations in the code use one thickness for the entire head. On large diameter thin heads the center or spherical area is often thicker than the knuckle area due to the method of manufacture. Including this extra material in the design calculations results in an increase of the MAWP of large diameter thin heads. VIII-2, AD-200 of the code permits localized thinning in a circumferential band in a cylindrical shell. Applying these same rules to elliptical heads would permit thinning in the knuckle region as well. Engineers have powerful finite element analysis tools that can be used to accurately determine levels of plastic strain and plastic deformed shapes. It is proposed that VIII-2 Appendix 4 and 5 methods be permitted for the design of elliptical heads. Doing so would permit significant decreases in thickness requirements. Different methods of Plastic Finite Element Analysis (PFEA) are investigated. An analysis of a PVRC sponsored burst test is done to develop and verify the PFEA methods. Two designs based on measurements of actual vessels are analyzed to determine the maximum allowable working pressures (MAWP) for thick and thin heads with and without local thin regions. MAWP is determined by limit analysis, per VIII-2 4-136.3 and by two other proposed methods. Using Burst FEA, the calculated burst pressure is multiplied by a safety factor to obtain MAWP. Large deflection large strain elastic perfectly plastic limit analyses (LDLS EPP LL) method includes the beneficial effect of deformations when determining the maximum limit pressure. Elliptical heads become more spherical during deformation. The spherical shape has higher pressure restraining capabilities. An alternate design equation for elliptical heads based on the LDLS EPP LL calculations is also proposed.
Thermal Shock Failure Analysis and Remediation Design of an Internal Catalyst Structure
Authors: Camburn John E. , Saunders Kenneth L.
Published: August 2008

The catalyst structures of interest are internals for four identical cogeneration units which together produce about one half million kilograms per hour of steam for an adjacent refinery and 385 megawatts of electricity. They are structural steel frames made of 304SS with approximate dimensions of 42 feet high by 38 feet wide by 8 feet deep. During start up of the heat recovery steam generator (HRSG) units, hot combustion gases from the gas turbine exhaust flow through the HRSG units producing rapid heating of the interior components. However, because the catalyst structure internals are not pressure containing like the HRSG units, they were designed using structural codes that do not consider thermal loading. Cracking was observed along leading edges of structural members and at the connections of cross bracings. A transient thermal analysis was completed to calculate temperature distributions as a function of time at the critical locations. Thermal stress calculations were then prepared and stress values compared to fatigue curves for the material at temperature. It was found that computed thermal stress values were sufficient to initiate and propagate cracks consistent with those observed. Several remediation options were considered before two were selected and design changes were detailed. The remediation options included removing some of the bracing after a detailed seismic analysis showed that they were not required and adding refractory materials to leading edges to minimize the thermal gradients generated during start up of the HRSG units. Thermocouple data collected at remediation locations and unchanged areas during start up supported the hypothesized failure analysis cause and the benefit of the remediation design changes.
Vibration Modes of Spherical Shells and Containment Vessels
Authors: Duffey Thomas A. , Romero Christopher
Published: August 2008

Spherical pressure vessels are used to fully contain the effects of high explosions. In this paper, the vibrations of a spherical containment vessel undergoing elastic response are investigated. Vibration modes of containment vessels are of particular interest, as it is the superposition and interaction of different modes of response with closely spaced frequencies that has been reported to be the mechanism of ‘strain growth’. First, the modal frequencies of a spherical shell for both axisymmetric and nonaxisymmetric response modes are discussed, based on a sequence of papers that have appeared in the open literature. Analytical predictions are then compared with numerical simulations using ABAQUS. It is found that the numerical simulations accurately predict both the axisymmetric and nonaxisymmetric modal frequencies for the complete spherical shell. Next, numerical simulations of modal frequencies for the more complex spherical containment vessel (with nozzles) are compared with the spherical shell results. Numerical simulations for the spherical containment vessel reveal that frequencies are somewhat similar to the complete spherical shell. Limited comparisons with experimentally recorded frequencies for participating modes of vessel dynamic response during high explosive containment testing are presented as well.
Convergence of the Axisymmetric Bessel Function Solution to the Pipe Strap Anchor Problem
Authors: Williams Dennis K.
Published: August 2008

One of the paradigmatic problems that frequently arise within a piping flexibility analysis is need to quantify the effect of local stresses created by supports and restraints attachments. Over the past twenty years, concerns have been identified by both regulatory agencies in the nuclear power industry and others in the process and chemicals industries concerning the effect of various stiff clamping arrangements on the expected life of the pipe and piping components. In many of the commonly utilized geometries and arrangements of pipe clamps, it has previously been shown by the author that some pipe clamp anchors can be treated as an axisymmetric elasticity problem. These pipe anchors may be simplified considering the axisymmetric stress and deformation determination within a hollow cylinder (pipe) that is subjected to appropriate boundary and loading conditions, per se. One of the geometries previously considered and addressed is comprised of two pipe clamps that are bolted tightly to the pipe and affixed to a modified shoe-type structure. The shoe is employed for the purpose of providing a theoretically immoveable base that can be easily attached either by bolting or welding within a pipe rack. Because the Bessel function and Fourier solution relies on the summation of a large number of terms (i.e., a series type solution), convergence becomes an issue when time is of the essence. This paper addresses the two variables that need to be controlled to obtain acceptable results with the series type solution.
Stiffness Coefficients for Nozzles in API 650 Tanks
Authors: Lengsfeld Manfred , Bardia Kanhaiya L. , Taagepera Jaan , Hathaitham Kanajett , LaBounty Donald G. , Lengsfeld Mark C.
Published: August 2008

The analysis of tank nozzles for API Standard 650 [1] tanks is a complex problem. Appendix P of API 650 provides a method for determining the allowable external loads on tank shell openings. The method in Appendix P is based on two papers, one by Billimoria and Hagstrom [2] and the other by Billimoria and Tam [3]. Although Appendix P is optional, industry has used it for a number of years for large diameter tanks. For tanks less than 120 feet (33.6 m) in diameter, Appendix P is not applicable. In previously published papers [4–10], the authors used finite element analysis (FEA) to verify the experimental results reported by Billimoria and Tam for shell nozzles. The analysis showed the variance between stiffness coefficients and stresses obtained by FEA and API 650 methods for tanks. In this follow-up paper, the authors present stiffness coefficients for tank nozzles located away from a structural discontinuity. Factors to establish spring rates for nozzles varying from 6 to 48 inches and tank diameters from 30 feet to 300 feet and for nozzles at different elevations on the shell are provided. Mathematical equations are provided together with graphs for the stiffness coefficient factors.