varunr14/newsummary huggingface dataset:
Surface roughness affects the friction behaviour stress distribution and surface quality moreover this influence is more significant when scaling down the strip size . A novel approach has been proposed to investigate the surface roughness in asymmetric rolling based on Finite Element Analysis . Evolution of asperity flattening contact area ratio and surface roughness is investigated under various simulation rolling conditions . The model reviewed numerical solutions for real surfaces with asperities of arbitrary shape and varying size and height distributions . The rolling characterization has also been identified for asymmetric rolling . The difference of change in surface roughness for upper and lower strip surface is large during rolling . The effect of the speed asymmetry factor on strip bending has been established . An increase of the speed asymmetry factor causes an increase in the strip curvature while the force parameters decrease with increasing asymmetry factor . The speed asymmetric factor influences the strip bending significantly . It is the first attempt to carry out this kind of research in surface roughness based on real surface during asymmetric rolling of thin strip . 


Highlights:
Numerical solution for real surface with asperities of varying height distribution. The force parameters decrease with increasing speed asymmetry factor. An increase of the asymmetry factor causes an increase in the strip curvature. First attempt to modelling the surface roughness in asymmetric thin strip rolling.
In the present paper the effect of graphite nodularity in the microstructure of cast iron is assessed with respect to its machinability at orthogonal cutting . A micro structure based model of the cast iron material has been developed based on analyses of micro graph images . The image analysis combines pearlitic grains with graphite nodules to produce the micro structures . Continuous deformation behavior of pearlite and graphite phases is described using the Johnson Cook viscoplasticty model including temperature dependence . Of particular concern is the modeling of the chip formation induced by the micro structure morphology and the mechanical behavior of the work piece material in the vicinity of the insert . This is described by the element deletion methodology along with the Johnson Cook failure criterion to realize the fracture kinematics . A parametric study is carried out by varying the nodularity of the graphite . To validate the model the finite element results are compared to machining test results carried out on a Compacted Graphite Iron material in a related paper . It turns out that the FE simulated and experimentally observed cutting force and chip formation compare fairly well . 


Highlights:
A FE based machining simulation methodology accounting for cast iron microstructure. Assessment of cast iron machinability at orthogonal cutting. A parametric study is carried out based on micrographs of cast iron with varying nodularity. FE simulated and experimental cutting forces and chip formations compare fairly well.
The requirement of repeated evaluation of structural responses in typical sensitivity based Finite Element Model Updating procedure limits its popular applications for large structures . The least squares method based response surface method is applied as a potential alternative for responses approximations in iterative model updating procedure . However the LSM is a major source of error in response prediction and the moving least squares method is found to be more efficient in this regard . An attempt has been made in the present study to explore the effectiveness of MLSM based RSM in FEMU . A comparative assessment is performed between the MLSM based and the conventional LSM based RSM for model parameter updating . The comparative study is being illustrated with the help of two example problems using artificially generated input responses . It is generally observed that the MLSM based RSM identifies better than the LSM based approach . 


Highlights:
Moving least squares method MLSM based response surface method RSM for model parameter updating. Comparative assessment between the MLSM based and the conventional least squares method LSM based approach. The MLSM based RSM identifies better than the LSM based approach.
The major addressed issue in this paper is investigation of impressive parameters on initiation and propagation of debonding in the adhesive layer when it occurs concurrently with the growth of an initial crack in a single side repaired aluminum panels by composite patches under cyclic loading . Using the softening behavior of thin layer solid like interface elements debonding is modeled between the composite patch layer adjacent to the aluminum panel as a function of loading condition and stress field . A user element routine and two damage model routines were developed to include the interface element and to simulate the distribution of damage in adhesive layer under static and cyclic loading . Fatigue crack growth in aluminum panel was also modeled using a simple approach developed by the authors . It is shown that it is possible to decrease the debonding propagation by implementing appropriate composite patch and adhesive dimensional and material properties . 


Highlights:
A high cycle fatigue de cohesive constitutive law is used for debonding investigation of composite patch cracked panel interface. Effects of material width and thickness of patch and bonding strength on progressive damage of bonding interface are investigated. A patch material with larger elastic modulus thickness and adhesive thickness leads to more damages in the adhesive bound line. By increasing the adhesive strength and patch width the de bonding and crack growth rate of the panel are decreased.
We address in this paper an isogeometric finite element approach in combination with the third order deformation plate theory for thermal buckling analysis of functionally graded material plates . TSDT accounts shear deformation effect without requiring any shear correction factors . The IGA utilizes non uniform rational B spline as basis functions resulting in both exact geometric representation and high order approximations . It enables to achieve easily the smoothness with arbitrary continuous order . The present method hence fulfills the C 1 requirement of TSDT model . The material properties of FGM plates are assumed to vary according to power law distribution of the volume fraction of constituents . The temperature field through the plate thickness is described by a polynomial series . The influences of length to thickness ratio aspect ratio boundary conditions and material property on the temperature critical buckling are investigated . Numerical results of circular and rectangular plates are provided to validate the effectiveness of the proposed method . 


Highlights:
We address an isogeometric finite element formulation for thermal buckling analysis of functionally graded material plates. The method does not require any shear correction factors due to using third order deformation plate theory TSDT . The method utilizes non uniform rational B splines NURBS instead of standard Lagrange basis functions. It is very flexible with refinement and degree elevation with an arbitrary continuity level by NURBS basis functions. Intensive numerical studies have been conducted to show the good performance of the present method.
In this paper the effect of initial geometric imperfections on the buckling load of steel tubes under axial load and lateral pressure is investigated . The geometric imperfections are modeled as a 2D 1V non homogeneous Gaussian stochastic field simulated using the spectral representation method . The evolutionary power spectrum of the non homogeneous field is derived from available experimental measurements using the recently proposed method of separation . For the determination of the limit load variability of the tubes a stochastic formulation based on Monte Carlo simulation is implemented . It is shown that the imperfections can lead to a substantial reduction of the buckling load and thus should be taken into account via a realistic description through stochastic field modeling . 


Highlights:
The buckling load variability of imperfect steel tubes is investigated. The imperfections are modeled as a non homogeneous Gaussian stochastic field. Evolutionary power spectra are derived from experimental measurements. The imperfections can lead to a substantial reduction of the buckling load. The type of loading and the imperfections affect the failure modes of the tubes.
The research goal is to develop a numerical method and computer code to inverse compute the multilayer moduli of a flexible pavement structure . A finite element model with infinite elements on the infinite half spaces of boundaries is developed to model pavement responses . A Newton Raphson iteration procedure is proposed to inverse compute the multilayer moduli . Compared to most conventional analytical approaches it could account for temperature profile and associated modulus variation . A computer code is developed for the entire numerical computation . An average error of 1.77 10.83 8.99 and 1.08 is achieved for the inversed moduli of asphalt layer base subbase and soil respectively based on 5000 dataset for validation . The method could also inverse compute the modulus variation of the top asphalt layer due to temperature profile with an average error of 4.45 attained for three examples in cold regular and hot weather conditions . 


Highlights:
We developed a numerical method and code to inverse multilayer moduli. It accounts for temperature profile and modulus variation. Empirically estimated moduli seeds improve engineering accuracy. Moduli seeds have minimal effects on the numerical accuracy.
When creating simplified models of the vehicle structure 1D beam elements are normally used to obtain a small sized and parametric representation of all beam like parts . Despite its undoubted advantages such an approach can introduce certain modeling errors . They are influenced by various factors such as cross section deformations spot welds flanges discontinuities and beam cross section geometry . The aim of this paper is to perform a systematic study of these error factors and their potential impact on the model accuracy . Consequently guidelines are given on good practices for overcoming the intrinsic limitations of 1D beam concept modeling techniques . For this purpose six different beam structures with idealized geometry are studied . Furthermore three beam like parts of a vehicle body are also investigated . The derived good modeling practices are applied to a couple of industrial case studies both at car body level . By giving a better insight of the potential pitfalls and their possible solutions 1D beam concept modeling can become more accurate and reliable . 


Highlights:
Systematic study of the error factors in 1D beam concept modeling for the vehicle structure. Research on beam spot welds flanges and discontinuities cross section geometry and deformations. Introduction of a novel cross section deformation measure. Derivation of guidelines on good modeling practices to improve the concept stage. Successful application of the methodology to a couple of industrial case studies.
In this paper a thermal structural coupled finite element analysis method for wear prediction of seal is proposed . The methodology is built with iterative wear prediction procedure in which the geometry of the contact interface is progressively changed according to the wear model . To perform finite element simulation of wear process a novel mesh reconstruction strategy to reflect the evolution of geometry caused by the wear is presented . Considering that friction heat in the sealing area normally has important effects on wear process thermal behavior of wear process analysis is carried out and the friction heat flux density is calculated as one of the boundary conditions in each wear simulation circle . Two kinds of seals namely O shape seal and rectangular section seal are investigated in this paper . As the sealing force is important for seals to evaluate the sealing capability the effect of wear is reflected through the change of sealing force . The numerical results supply a suggestion for the applications of both seals . 


Highlights:
A thermal structural coupled finite element method for wear prediction of seal. A mesh reconstruction strategy for reflecting the evolution of geometry of seal caused by wear. Thermal behavior coupled with structural analysis in comprehensive FE model. Sealing force is chosen as the criterion to evaluate the performance of seal. O seals are more suitable for low fluid pressure and high speed environment than R seals.
In this paper two new elements for three dimensional finite element analysis of cable structures are proposed . The tangent stiffness matrices of the cable elements are derived under spatially concentrated and distributed static and thermal loads . The first element which is called Continuous Catenary Cable element and extends the classic catenary cable element presents the explicit forms of the stiffness matrix and internal force vector of the cable . The second element Discrete Catenary Cable element is introduced by transforming the continuous equations of the CCC element into discrete formulation giving the capability of dividing the cable into several straight elements with axial behavior . The DCC element having all the features of the CCC element has the advantages of including more three dimensional loadings such as point loads along the member and non uniform distributed lateral loads and incorporating various geometrical and material nonlinearities such as cable cross section variation and cable material yielding . Thereafter employing the proposed elements we have presented a simple algorithm for the analysis of pretensioned cables . The proposed elements are then used for nonlinear analysis of cable structures and the response is compared with those obtained by other researchers . The results of numerical examples indicate the capability and robustness of the proposed elements in predicting the deformation response of cable structures . 


Highlights:
Two new elements for 3D finite element analysis of cable structures are proposed. The elements are applicable for all uniformly distributed 3D point and thermal loads. Algorithms for calculating the stiffness matrix and the internal force vector are presented. The acceptable convergence of the new models their simplicity and direct equations are shown. Both continuous and discrete models provide good accuracy while the latter is faster.
Continuous fiber reinforced composite materials are extensively being used in helicopter dynamic structures . Preimpregnated fibers or prepregs are used to produce high quality composite rotor yokes flex beams . One process in particular known as cavity molding is frequently used to process high quality thick composite details with exceptionally precise dimensions by using a platen press to apply heat and pressure to rigid tooling and thereby entice the prepreg within to cure into the shape of the confines of an internal cavity . The objective of the research described here is to develop a mathematical model for glass epoxy prepreg which simulates the resin flow heat transfer consolidation and curing of cavity molded flex beams which varies significantly with location . An enhanced understanding of the mechanisms involved will help significantly improve the cost effectivity of molding process development . The current work is focused on process modeling of composite flex beams which are manufactured by cavity molding . The cure kinetics of such parts is particularly difficult to model because tool part geometries are complex . The combined effects of heat transferred by the tool and heat spontaneously generated by the reacting thermoset during cure results in significant gradients of resin advancement throughout the part . The temperature spikes that result from internally generated exothermic heat can not be quickly dissipated because of the low thermal conductivity of composite . Various governing equations are presented here that describe the resin cure kinetics thermal energy balance and flow during the process . A general purpose finite element package with multiphysics capabilities is used for simulating the non isothermal prepreg press process the degrees of cure and temperature field distribution at different cross sections . 


Highlights:
Integrated cure and flow processes have been modeled. Process modeling of cavity molding process for composite flex beams is new. Level set method has been used to model the flow behavior. Flex beam manufacturing has been analyzed as non isothermal prepreg press process. Exothermic behavior of resin has been validated.
A number of highly threaded many core architectures hide memory access latency by low overhead context switching among a large number of threads . The speedup of a program on these machines depends on how well the latency is hidden . If the number of threads were infinite theoretically these machines could provide the performance predicted by the PRAM analysis of these programs . However the number of threads per processor is not infinite and is constrained by both hardware and algorithmic limits . In this paper we introduce the Threaded Many core Memory model which is meant to capture the important characteristics of these highly threaded many core machines . Since we model some important machine parameters of these machines we expect analysis under this model to provide a more fine grained and accurate performance prediction than the PRAM analysis . We analyze 4 algorithms for the classic all pairs shortest paths problem under this model . We find that even when two algorithms have the same PRAM performance our model predicts different performance for some settings of machine parameters . For example for dense graphs the dynamic programming algorithm and Johnson s algorithm have the same performance in the PRAM model . However our model predicts different performance for large enough memory access latency and validates the intuition that the dynamic programming algorithm performs better on these machines . We validate several predictions made by our model using empirical measurements on an instantiation of a highly threaded many core machine namely the NVIDIA GTX 480 . 


Highlights:
We design a memory model to analyze algorithms for highly threaded many core systems. The model captures significant factors of performance work span and memory accesses. We show the model is better than PRAM by applying both to 4 shortest paths algorithms. Empirical performance is effectively predicted by our model in many circumstances. It is the first formalized asymptotic model helpful for algorithm design on many cores.
An h adaptive remeshing scheme dedicated to the simulation of macroscopic ductile cracks initiation and propagation during metal forming processes is proposed . Cracks are represented using a procedure based on fully damaged elements deletion . Element size inside the domain and along the crack path located inside highly localized zones is driven by error indicators based on geometrical considerations and the derivatives of physical quantities calculated by diffuse approximation . Saw tooth effects along the crack are smoothed with the use of Bezier curves in order to reduce computational inaccuracy . The mesh can be refined and an important issue of this work is mesh coarsening in order to ensure a reasonable computational cost . Multiple domains can be handled . The procedure can be easily integrated in any standard nonlinear explicit finite element code . Specific fields transfer procedures and an automatic adaptation of the time loading sequences are also presented . The efficiency and robustness of the proposed strategy are validated through some examples which show a good agreement with experimentally observed ductile crack paths under large inelastic strains . 


Highlights:
An h adaptive methodology suitable for metal forming processes with damage is proposed. Mesh coarsening is performed inside inactive areas where no plastic flow occurs. We propose geometrical and diffuse approximation based physical error indicators. Field transfer procedure at integration points is based on diffuse approximation. Loading sequence is adapted with the size and number of fully damaged elements.
The one dimensional viscous Burgers equation with a time periodic inflow boundary condition is investigated within the context of a newly developed optimal spatiotemporal reduced order modeling framework . Flow simulations are carried out with a conventional finite difference scheme and are expedited by coarsening the computational grid in space and time . The OPSTROM framework is used to maintain reliable predictions for the flow by constructing interactive subgrid scale models to account for the effects due to unresolved spatial and temporal scales . Model construction is data driven and is based upon principles of mean square error minimization conditional expectations and stochastic estimation . The results indicate a need to model both subgrid spatial and temporal scales in order to improve the accuracy of under resolved simulations . 


Highlights:
We investigate an optimal spatiotemporal reduced order modeling framework. The viscous Burgers equation serves as a test problem. Models are developed to account for the effects of unresolved spatiotemporal scales. Model construction is simplified through a number of observed statistical properties. Results indicate an ability to improve the reliability of under resolved simulations.
The paper presents an approach for the identification of elasto static parameters of a robotic manipulator using the virtual experiments in a CAD environment . It is based on the numerical processing of the data extracted from the finite element analysis results which are obtained for isolated manipulator links . This approach allows to obtain the desired stiffness matrices taking into account the complex shape of the links couplings between rotational translational deflections and particularities of the joints connecting adjacent links . These matrices are integral parts of the manipulator lumped stiffness model that are widely used in robotics due to its high computational efficiency . To improve the identification accuracy recommendations for optimal settings of the virtual experiments are given as well as relevant statistical processing techniques are proposed . Efficiency of the developed approach is confirmed by a simulation study that shows that the accuracy in evaluating the stiffness matrix elements is about 0.1 . 


Highlights:
FEA based methodology for stiffness matrix identification. Numerical technique for computing the stiffness matrix from the deflection field. Analytical expressions for accuracy evaluation. Technique for statistical processing of the experimental data matrix.