Prodyot K. Basu

Automobile body reinforcement by finite element optimization

This paper is concerned with design optimization of material reinforcement of automobile body for rigidity improvement. Two finite element optimization techniques, topology optimization and sizing optimization, are explored to find out an optimal manufacturing feasible design from multiple optimized designs. The application of these methods demonstrates that through innovative utilization of the topology optimization technique, an optimal manufacturing feasible design can be obtained. The relationship between the rigidity improvement and different configuration of material reinforcement is also investigated. It is concluded that through appropriate application of finite element optimization methods, the overall rigidity of the automobile body can be improved substantially in a cost effective manner.

Free vibration of skew Mindlin plates by p-version of F.E.M.

Abstract Accurate natural frequencies and mode shapes of skew plates with and without cutouts are determined by p -version finite element method using integrals of Legendre polynomials for p =1–14. The hierarchical plate element is formulated based on Mindlins plate theory including rotatory inertia effects and based on a skew co-ordinate system. Non-dimensional frequency parameter and mode shapes are presented for a range of skew angle ( β ), aspect ratio ( a / b ), thickness–width ratio ( h / b ), cutout dimensions and different boundary conditions. The results were verified by comparison with those available in the open literature.

Development of a web-based mass transfer processes laboratory: System development and implementation

A web‐based environment is utilized as a means to introduce advanced mass transfer processes concepts in environmental engineering and science courses. System development and implementation is presented, including detailed descriptions of the techniques employed to link software written in high‐level computer languages such as C++ and FORTRAN to an internet‐based, user‐friendly graphical user interface for both program input and output.

Higher-order modeling of continua by finite-element, boundary-element, meshless, and wavelet methods

Abstract This paper is an overview of the higher-order modeling schemes for the continua based on finite-element, boundary-element, meshless, and wavelet methods. The first discrete numerical method is well established, so discussions are mainly focused on the last three methods. Apart from critically discussing the main theoretical, algorithmic, and implementation characteristics of the methods, the paper expounds on the relative merits and demerits of the methods. The results of a number of smooth and nonsmooth problems are presented. Finally, the future potential of the wavelet method in discrete numerical modeling of continua is explored.

Analysis of singular cylindrical shells by p-version of FEM

Abstract A new hierarchic p-version cylindrical shell element based on exact mapping is presented. Its rigid-body modes, round-off error, and convergence characteristics are investigated. Its performance in the presence of singularities is demonstrated with the help of three test problems, namely pinched cylinder problem, Lockheed test problem 2, and cracked cylinder problem.

Materially and geometrically nonlinear analysis of laminated anisotropic plates by p-version of FEM

Abstract A p-version finite element model based on degenerate shell element is proposed for the analysis of orthotropic laminated plates. In the nonlinear formulation of the model, the total Lagrangian formulation is adopted with moderately large deflections and small rotations being accounted for in the sense of von Karman hypothesis. The material model is based on the Huber–Mises yield criterion and Prandtl–Reuss flow rule in accordance with the theory of strain hardening yield function, which is generalized for anisotropic materials by introducing the parameters of anisotropy. The model is also based on the equivalent-single layer laminate theory. The integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. Gauss–Lobatto numerical quadrature is used to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed p-version finite element model is demonstrated through several comparative points of view in terms of ultimate load, convergence characteristics, nonlinear effect, and shape of plastic zone.

Design optimisation of automobile welds

This paper presents the design optimisation procedure for the automobile welds based on the sizing optimisation technique. The purpose is to reduce the number of welds and save the cost, while the rigidity requirements are satisfied. A special element is proposed to model the spot weld by a serial combination of a rigid element and a 3-dimensional elastic element. Through the innovative utilisation of optimisation techniques, the optimal weld design is obtained. Furthermore, by using different weld reduction constraints to study critical areas, the relationship between the overall rigidity of an automobile body and the quantity of weld is determined. It is concluded that by using appropriate optimisation schemes as presented, the quantity of weld of an automobile body can be substantially reduced and cost savings can be achieved. The proposed method can be used as guidance in optimising existing or new designs of automobile welds.

A parallel programming environment for adaptive p-version finite element analysis

Abstract This paper presents a parallel programming environment for solving large-scale problems using adaptive p-version finite element approach. A scalable parallel feedback algorithm based on domain decomposition technique has been developed to incorporate the parallelism in adaptive finite element analysis of large-scale structures. This algorithm is implementable on MIMD type parallel processors, and uses p-extension of the finite element method. Modeling with p-version finite elements needs special considerations of load-balancing, and this has been incorporated in present domain decomposition technique using semi-empirical approach. The Connection Machines CM-5 system has been used to implement the present system. Most of the previous attempts to parallelize adaptive finite element analysis were confirmed to parallel algorithms for direct or iterative equation solvers, and did not produce satisfactory performance because of small granularity of parallel tasks. Also these efforts were based on h-version of the finite element method, and hence could not exploit some of the special advantages available in p-vision of finite element approach. As the feedback algorithm is based on an iterative scheme, utilizing the domain decomposition technique, it produced good performance, particularly for large-scale structures. It has been tested for a number of regular and irregular two-dimensional problems showing good convergence characteristics.

Stress Analysis of Bonded Patched Plates with Circular Cutout Using Full-Discrete Layer Model

To predict the static response of patched plates with circular cutout, a full-discrete layer model is proposed. The shape functions are based on 2D and 1D integrals of Legendre polynomials, allowing accurate simulation of 3D behavior. Exact mapping of curved boundary is undertaken using blending functions. The easy to use modeling scheme is applied to single-patch repaired plates with circular cutout and compared with published results. The results of parametric studies on patched plates are presented by varying the relative thicknesses of patch and adhesive, patch shape, and patch size.

Parallel adaptive finite element analysis of large scale structures

Abstract A scalable parallel feedback algorithm for adaptive finite element modeling of large scale structures is presented. This algorithm is implementable on MIMD parallel processors, and uses the p-extension of the finite element method. The problem domain is partitioned into a number of suitable subdomains by using an automatic domain decomposer, and each subdomain is thereupon assigned to a processor in the multiprocessor system. Connection Machines CM-5 system is being used for the present implementation. Most of the previous efforts to parallelize finite element analysis were confined to parallel algorithms for direct or iterative equation solvers, and did not produce satisfactory performance because of the small granularity of parallel tasks. Also, these efforts were based on the h-extension of the finite element method, and hence could not exploit some of the inherent advantages available in the p-extension. As the current algorithm utilizes the domain decomposition technique and is based on the p-version of the finite element method, it is expected to produce good performance, particularly for large scale structures. The feedback algorithm is based on an iterative scheme derived from the domain decomposition technique for applications to problems of solid mechanics. It has been tested for two-dimensional problems showing good convergence characteristics. Current efforts are also directed towards generalizing the scheme, and include adaptive model refinement.