1998-09-29

Slam Life Assessment Method for Closures Durability 982307

ABSTRACT

The Slam Life Assessment Method (SLAM) is a CAE solution that predicts the durability of automotive closures subject to a repetitive slamming load. Moreover, SLAM is a fully automated program that integrates several software and CAE analyses into a single turnkey solution.

SLAM employs the physics of the slam event to succeed where prior analysis methods fail. Standard CAE analyses such as inertia relief, normal modes, and forced loading response cannot capture the physics of the dynamic stress states that occur during a durability slam event. Furthermore, SLAM produces insight into the behavior of the door system that cannot be gained through testing. We have shown that it is possible to predict the performance of a door subject to a slam-closed event with 80-90% reliability.

This method has been realized via motivation to solve numerous door panel cracking issues associated with preliminary door designs. Correlation of SLAM methods with physical tests led to the ability to “virtually” slam and redesign doors before prototypes were made. To date, SLAM is used mainly on door systems, however, it is easily extended to hood, decklid, and liftgate systems. SLAM simulations have proven their usefulness on aluminum hood “tea cup” designs.

SLAM saves product development time and money by reducing the number of prototypes needed to evaluate a design proposal. It allows evaluation of more design alternatives, reduces weight, and results in fewer production level failures. As the automotive industry moves towards a 10-year durability life, the testing times and number of samples continues to increase in order to meet these tougher requirements. Door slam testing can take several months to schedule and complete, whereas, SLAM can reduce this process to a few hours. The net result is a benefit to the customer in the form of a structurally optimized closure assembly that has no durability problems.

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