Investigation of Mechanical Performance of Automotive Lighting Device under Random Vibration Loads

Abstract

Predicting mechanical performance of thermoplastics is very important because stylistic and complex geometrized products are validated
through OEM (Original Equipment Manufacturer) test standards, that product should promise a customer confident design and also satisfy a
good lighting performance. Hence, headlamp design made of thermoplastics, mineral filled Polypropylene (PP) for body, Polycarbonate (PC)
for outer lens and stylistic components, is investigated under random vibration loads supplied by OEM test standard and predicting mechanical
performance of thermoplastics becomes very important. Tensile tests are utilized in predicting mechanical performance of materials, with dog
bone type test specimens at 1mm/min tensile test speed. Design validation is achieved through finite element vibration simulations until initial
injection moulded components are produced where design phase is finished by design validation tests. It is critical to characterize mechanical
behaviour of thermoplastics as directly affected from injection pressure, design space (CAD geometry). Travel distance of thermoplastic material in design space affects mechanical performance. Increasing travel distance decreases mechanical performance of final product, also increase
in injection pressure results in enhanced and tough product. Finite element vibration simulations performed with material data from dog bone
type test coupon resulted in poor correlation with product validation tests. However, test coupon cut from moulded component and mechanical
properties predicted through tensile tests has a very good correlation with design validation tests.