Template:Stress-Strength Analysis in Design For Reliability

Stress-Strength Analysis in Design For Reliability

The stress distribution usually can be estimated from customer usage data. For example, the milage per year of a passanger car, or the load distribution for a beam. The strength distribution is affected by the material used in a component, the geometric dimension, and the manufacturing process. By adjusting these factors, a strength distribution that meets the reliability goal can be obtained. The reliability goal is used to decide the distribution goal of the strenght. As we know, the expected reliability is callled from the following stress-strength calculation:

[math]\displaystyle{ R=P[Stress\le Strength]=\int_{0}^{\infty }{{{f}_{Stress}}(x)\cdot {{R}_{Strength}}(x)}dx }[/math]

Since the stress distribution can be estimated from customer usage data, it can be assumed to be known. For a given reliability goal, the strength distribution is the only unknown and can be solved from the above equation. The following example explains how to use Weibull++ to determine the parameters for a strength distribution.