Survey of Existing Literature in the Field of Shock-Absorbing Materials with a View to Subsequent Adaptation of Plastic Deformation Codes. Phase 1

摘要

Shock-absorbing materials and structures can be used as part of the transport container structure or of the truck equipment. An extensive survey of the literature has provided much information. Investigation has been made to define the required experimental procedures necessary to measure the missing material properties. Three codes had been selected: EURDYN, MARC-CDC and SAMCEF. For code evaluation, a schematic container model has been considered to serve as a benchmark for the evaluation of plastic deformation. For the shock-calculation, the container falls from a height of 9 meters along the direction of its cylinder axis on an unyielded flat surface. The EURDYN computer code, has been selected first as it is especially designed to handle dynamic problems, preferably plastic ones. Indeed, EURDYN uses an explicit integration scheme versus time, which makes it quite efficient to run short deformation processes such as absorber collapses. The SAMCEF computer code could not readily calculate the benchmark, also a visco-plastic flow model has been added to it. The MARC computer code was supposed to be a candidate to run shock-calculation but extensive computing time and engineering efforts would be required, it was replaced by the PLEXUS code. The results obtained using the SAMCEF program confirm those obtained with EURDYN. The PLEXUS results are in between. The proposed benchmark calculation is at the border of the capabilities of the most advanced computer codes for plastic-dynamic calculations. Indeed, a complex energy absorption process seems to take place in a narrow region, moving versus time, where very large shape inversions occur. That requires an accurate modelling of the system in the deformed regions and a skilful choice of the numerical parameters of the computer run. The three tested codes gave qualitatively consistent results and confirm some scarce experimental results.