Search Results

The objective of this research is to understand the crashworthiness performance of composite inserts in vehicle structure and to improve the numerical model of steel-composite combined structure for providing better prediction in the design process of composite inserts. A simplified steel-composite combined beam structure is used for three-point bending tests. Epoxy-based structural foam and 33% short glass fiber reinforced nylon composite insert are considered as composite fillers in empty sections of double hat-type steel beam structure. Four cases based on the different combination of composite materials are considered. In the series of physical three-point bending tests, the force-displacement (F-D) curves and material behaviors are investigated. The test results show that the composite insert greatly contributes to improve the crashworthiness of beam structure as well as to reduce the vehicle weight.

A simple and accurate analytical expression relating the expected process (long term) and sampling (short-term) product variability is developed using a variational mathematical principle. Of the several complex functional forms discovered, simplicity and ease of use are used to select an expression providing the most reliable estimation for and convenient expression of Z score (σ level) as a function of defects per opportunity (DPO) or per million opportunities (DPMO). In the absence of scientific calculators or computers, this expression allows engineers to accurately estimate long term process variability to within 0.01 of its true value without resulting to (laborious) tables or a computer. Also, a high precision approximation is provided for cases when DPO is less than 1% which estimates Z-score to within 0.003 of the actual value (at 6σ).