CompositesWorld

SEP 2018

CompositesWorld

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10 CompositesWorld DESIGN & TESTING SEPTEMBER 2018 approximation of the expected properties desired in the target material) is available for development of preliminary design concepts, allowing specific material testing to be conducted in parallel and reducing the overall product development schedule. e modules are organized in three levels, each building on the others. As a product development program advances and higher resolution in the design performance evaluation is required, subsequent modules can be added to increase the fidelity of the results, with a corresponding increase in modeling predictability. Three levels of testing At the base of the program, the Module 1a package provides basic material card information required for modeling simulation up to first failure of the material. For the most basic applications, where stiffness and dynamic loading before failure are the design constraints, and the component or system is not factored into the overall vehicle crash performance, the data from Module 1a is sufficient. In addition to stiffness and strength-related design challenges, data from Module 1a Material Card testing is used for noise, vibration, harshness (NVH) simulation (modal analysis) and vehicle dynamics simulation. Module 1b, Crush Screening, is a series of tests designed to provide a quick assessment of crash energy performance. For those materials where post-failure crash performance is important, a relatively quick and cost-effective Crush Screening evaluation can be performed to evaluate combinations of materials (resins, fibers, additives) to assess their relative crash energy behavior. For applications where understanding post-first failure crash performance behavior is required, it will be necessary to advance to Modules 2a and 2b. ese modules focus on the material behavior after the first failure, when cracks begin to form and prop- agate through the material with increasing load and deformation. e level of fidelity derived from Module 2a testing will support initial structural component level crash modeling. To achieve a more accurate picture of the post-failure energy absorption behavior, Module 2b, a part-level hardware test of more complex three-dimensional components, is required. e additional fidelity provided by Module 2b results supports accurate modeling of larger, more complex subsystems (e.g., front- end modules/crush zones). e improved correlation between sample testing and modeling results can be seen in the graph in Fig. 2, p. 8. With each module that is performed, a considerable increase in simulation forecast quality is observed. Module 3a – Strain Rate Dependent Material Testing adds FIG. 3 Module 3b – Axial Crush testing is focused on emulating crash structure performance often seen in high-speed vehicle crash testing. Module 2a and 2b are not sufficient to model this behavior.

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