I recently wrote an article for our sister blog The HyperWorks Insider about automotive closures. It talks about the differing technologies required to engineer these systems from side doors to tailgates and liftgates, sliding doors and sunroofs to hoods/bonnets and trunk/boot lids.
It is an interesting time right now for closures in unexpected places. A couple of examples are the 4 door Porsche (Panamera) and 4 door Mini (Countryman) that are certainly a far cry from the 956 of Ferry Porsche and the original mini of Sir Alec Issigonis! There are also marques that are loosing doors; the Range Rover Evoque coupe is a definite departure from tradition. We are also now seeing liftgates on larger luxury sedans (I dare not call them big hatchbacks) such as the BMW 5 Series Gran Turismo and the Audi A7, both of which remind me of the Rover SD1 of the Seventies, which probably says more about me than the new models…
With all of this diversity and confusion of coupes that are SUVs and sedans that might be hatchbacks it certainly makes a good case for using a simulation driven design approach to closures. Engineers can call upon a range of technologies to develop new types of closures, including linear, non-linear implicit and explicit FEA, multi-body dynamics (MBD) and mechatronics, computational fluid dynamics and optimization. One particularly exciting technology is the Equivalent Static Load Method (ESLM). This is a new approach to the concept design and optimization of system level multi-body dynamic models.
ELSM represents a transient dynamic event with a static load history. Flexible and rigid bodies can be included in the optimization and all optimization disciplines are supported (topology, free size, topography, size, shape and free shape). Using ESLM ensures that designs are optimized for updated loads through an automated process that also removes any possible ambiguity about the boundary conditions – great for the development of closures where the mechanism design and structural design are proceeding in parallel.
There are a number of technologies that I didn’t get a chance to expand on in the article including model morphing and stamping simulation (both 1-step and incremental). Morphing can reduce the time to developing initial CAE models by up to 90%. Stamping simulation validates the manufacturing process and quickly identifies potential issues such as wrinkles and splits prior to cutting steel, avoiding the unnecessary costs associated with die machining and press downtime.
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