Showing papers by "Palaniappan Ramu published in 2004"

Safety Factor and Inverse Reliability Measures

Abstract: Probability performance measure and probability sufficiency factor are two inverse reliability measures that have gained importance as alternate measures of safety. Inverse measures have several advantages, including improving accuracy in response surface approximations, computational efficiency, and allowing easy estimates of resources needed for achieving the target safety levels. This paper establishes the relationship between the two inverse measures, and describes their advantages compared to the direct measures of probability and reliability index. Methods to compute the inverse measures are also described. Reliability based design optimization with inverse measure is demonstrated with a beam design example.

A convex hull approach for the reliability-based design optimization of transient dynamic problems

Abstract: Nonlinear problems such as transient dynamic problems exhibit structural responses that can be discontinuous due to numerous bifurcations. This hinders gradient-based or response surface-based optimization. This paper proposes a novel approach to split the design space into regions where the response is continuous. This makes traditional optimization viable. A convex hull approach is adopted to isolate the points corresponding to unwanted bifurcations in the design space. The proposed approach is applied to a tube impacting a rigid wall representing a transient dynamic problem. Since nonlinear behavior is highly sensitive to small variations in design, reliability-based design optimization is performed. The proposed method provides the designer an optimal design with a prescribed dynamic behavior.