Cost Effective Design Margins of Safety for ICME Materials

This paper presents a reliable, repeatable, easy-to-use method to compute a margin of safety on structures comprised of multi-phase materials.

One of the obstacles in the adoption of any material system is that engineering companies need to know how to write design margins of safety on the parts comprised of those materials. In the current design practice for ICME material systems, design allowables for margins of safety are derived from a building block of test information at a coupon or part level. Thus every potential structure comprised of the material system must be tested in a variety of environments over a variety of allowed operational conditions. Structural designs are only authorized on this candidate material system within the confines of these tests because only then can the engineers validate the design. Our research shows that adoption of a new material system would typically involve years of time and hundreds of thousands of tests at an average cost of $100 each. That means millions to tens of millions of dollars for each material system. These costs represent a nearly insurmountable obstacle to widespread adoption of ICME materials.

In this paper, we will present a different method of validating margins of safety that is based on the physics of the material system. This is much more like traditional metallics design methodology. So instead of requiring an expensive test matrix, this method requires only a dozen or so tests at the material system level...not at the coupon or part level. And the scope in which the designs are allowed to vary is unlimited because the method makes use of a materials-based criterion. The paper will include the application of this method to some traditional composite structure and will compare/contrast the outcomes and costs and design freedom with respect to current design practice