Reverse engineering in finite element analysis of the behaviour of lignocellulosic materials subjected to cyclic stresses

摘要

In all engineering fields, continuous improvement of products and processes is being pursued. Reverse engineering is a fast and innovative method of converting a physical model into a virtual one based on its physical and mechanical characteristics. The paper aims to develop the geometric and numerical virtual model of the behavior of a lignocellulosic material subjected to cyclical stresses (tensile-compression) based on mechanical characteristics determined through experimental tests. The importance of this study consists of identifying the simulation method by comparing the experimental results with the numerical results (engineering objective) and developing the working methodology with effect in the education for sustainable development. Modeling with the finite element method (FEM) based on the physical model aimed to determine the results spectrum which are interpolating with the experimentally ones. Thus, the CAD model of the real sample was made by attributing its physical and elastic characteristics using the HyperMesh (preprocessing) and HyperWorks software (post-processing). The model was meshed into QUAD4 elements, after which it were simulated the cyclical stresses on tensile-compression in successive stages, keeping in memory of each stage the changes made at the structural level in the previous stage. Finally, the theoretical results were compared with the experimental ones. The obtained results provide information about distribution of stresses and strains on each layer of material according to the type of stress, traction or compression, for each loading cycle. The values obtained with FEA are close to the experimental ones. The minor differences are due to using an approximate decrease of the modulus of elasticity after each stress cycle. To obtained the real values of Young’s Modulus after each cycle would have been necessary a big consumption of samples. The reverse engineering method has the advantage of material economy and the ability to carry out a large number of numerical models to replicate the material’s behavior more accurately to cyclical loading and even improve its properties by designing a new material.