COMPUTATIONAL & EXPERIMENTAL MECHANICS Dept. of Mechanical & Materials Engineering Universiti Kebangsaan Malaysia
MACM | IACM
Home About Members Research Project Collaboration Conference Publications Roadmap Students	Computation of powder forming is necessary to develop and to understand the effects of process variables on the product components. Advances in powder forming technology have resulted in the warm compaction process, which utilize traditional compaction equipment. Powder materials exhibit non-linearity in material properties, boundary and geometry. Efficient finite element simulation has been developed for powder forming and sintering processes. The research contribution includes the modelling of a complete compaction cycle process and thermo-mechanical calculation into the system of equations. Coupled thermo-mechanical analysis also has been developed, which incorporate staggered-incremental-iterative solution strategy. Further research opportunities are the crack determination during forming using discrete element methods and modelling of very large shrinkage phenomena. Parallel finite element model for crack propagation incorporating elastic-plastic features of the material is under development. The programs for crack growth simulations are implemented on the computer systems made up of a number of Intel Pentium III processors running in parallel under Beowulf clusters. Research is carried out in determining and visualising crack propagation of a 2-D plate under mixed modes loading. Further research includes the development of hybrid finite-discrete element methods in crack propagation calculation, crack-fracture modelling of brittle and ductile materials incorporating Monte Carlo simulation. Adaptive mesh methods refine discretization to make crack propagation simulation a highly irregular application. In exploiting parallelism and adaptivity, the research is now concentrates on development of algorithms for parallel mesh and solvers. The computational laminated composite mechanics research seeks to develop finite element codes for buckling and post-buckling of laminated composite plates under inplane compressive loads. The plate bending model is developed based on the displacement field of the first order shear deformation theory as an improvement of the classical plate theory. The higher order shear deformation theory for accurate distribution of shear stress in the thickness directions. The geometric non-linear model for this post-buckling analysis is based on the Von Karman non-linear strain. Research in the development of friction models is based on plasticity in a quasi-static motion. There are two fundamental issues in friction modelling; friction criterion and interface treatment. The associated and non-associated slip rule is applied to contact behaviour. The non-associated slip rule, by analogy, is the same as the associated flow rule in the Von-Mises criterion in plasticity. A robust treatment is associated by using an interface element in representing real situations of friction. Further research opportunities available are in the association of thermal effects in the friction criterion and parameter determination via experimental investigations. The computational mechanics of materials research seek to develop a constitutive model for shape memory alloys (sma) that can be applied to smart-structures. sma wires show complex non-linear stress-strain-temperature-martensite relationships. Finite element computation pictures the results of stress-temperature relations of sma and the deformation of column structure during heating. The research continues into the use of sma for industrial and medical applications. The computational fluid dynamics research looks at the modelling of thin section fillings for casting simulations. A model of the pressure die-casting has been developed, and the results are compared with experimental work. The research continues further to the couple of thermal calculations into the system of equations. Current research in pre-processing is in preparation of input data while, in post-processing, it is to visualise results from finite element computations. The software were developed using VisualBasic and AutoCAD via ActiveX. Users may choose to present results such as stress, pressure, temperature and density in solid or line contour. Additionally, arrows of different sizes determine the vector quantity. Finite element simulations have been carried out to solve industrial problems. Numerous industries have benefited from the advances of computing facilities. Commercial finite/discrete/boundary element software packages available include MSC Nastran, CFX, Pamstam, Elfen, Beasy, Cosmos/M and Lusas. Other CAE/CAD/CAM software includes Unigraphic, Ergoplan, Adams, Grasp, Cambridge Engineering Selector, Moldflow, Mastercam. For research purposes, comprehensive in-house finite element software has been developed with codes written in VisualC, VisualBasic, F77 and F90. OS systems used are NT-Windows, Unix and Linux for parallel computation.