Search Results

The Automotive industry’s use of digital technology such as Computer Aided Engineering (CAE) to perform virtual validation has progressed to effectively replace a large percentage of physical validation. This is primarily due to the increased accuracy and cost/time efficiencies that virtual validation offers compared to conventional physical prototyping and testing. With product development (PD) cycles becoming more compressed, CAE has assumed a more significant role in early, advanced design and structural evaluation. One of the areas where CAE is widely employed is in development of the Instrument Panel (IP) commonly referred to as the dashboard. For the purposes of this study, the term IP represents the plastic/polymer structure only, and not the full IP sub-system. The IP sub-system includes the structural member, the Cross Car Beam (CCB) assembly and all the IP mounted modules.

Motor vehicle safety standards are getting to be more demanding with time. For automotive interiors, instrument panel (IP) head impact protection is a key requirement of the Federal Motor Vehicle Safety Standard (FMVSS) 201. To ensure compliance of this requirement, head impact tests are conducted at 12 and 15 mph for performance verification. Computer simulation has become more prevalent as the primary development tool due to the significant reduction in time and cost that it offers. LS-DYNA is one of the most commonly used non-linear solvers in the automotive industry, particularly for safety related simulations such as the head impact of automotive interiors. LS-DYNA offers a wide variety of material models, and material type 024 (MAT 024, piecewise linear plasticity) is one of the most popular ones [1]. Although it was initially developed for metals, it is commonly used for polymers as well.

Occupant head impact simulations on automotive instrument panels (IP) are routinely performed as part of an integrated design process during the course of IP development. Based on the requirements (F/CMVSS, ECE), head impact zones on the IP are first established, which are then used to determine the various “hit” locations to be tested/analyzed. Once critical impact locations are identified, CAE simulations performed which is a repetitive process that involves computing impact angles, positioning the rigid head form with an assigned initial velocity and defining suitable contacts within the finite element model. A commercially available CAE process automation tool was used to automate these steps and generate a head impact simulation model. Once the input model is checked for errors by the automated process, it can be submitted to a solver without any user intervention for analysis and report generation.

Occupant knee impact simulations are performed in the automotive industry as an integrated design process during the course of instrument panel (IP) development. All major automakers have different categories of dynamic testing methods as part of their design process in validating their designs against the FMVSS 208 requirement. This has given rise to a corresponding number of knee impact simulations performed at various stages of product development. This paper investigates the advantages and disadvantages of various types of these knee impact simulations. Only the knee load requirement portion of the FMVSS208 is considered in this paper.