6. Design for , that is, the load can be taken by other members or the effect of fatigue failure otherwise mitigated, until the failed component can be detected and repaired or replaced. This approach is common in aircraft structural design. 7. create variations in dimensions, which can affect wear and fatigue properties. 8. is often used as the starting point to identify the most important problems and the most likel causes. blish

8. Design Problem: A material is needed to support a hanging sculpture with an overall tensile load of 800 N. It is important that the material not undergo any permanent deformation under this load and must have minimum volume/diameter. Using a circular rod, design structural components using your data for each of the three materials. Which material would you choose for the application and why? If the requirement was minimum weight, rather than minimum volume, which material would you use? Show sample calculations.

Given your understanding of what initiates and controls failure in materials, which of the following will increase the failure strength or lifetime of a test piece or component and why? a. Increasing the grain size so there are less grain boundaries to initiate failure b. Decreasing the temperature below the brittle-ductile transition temperature, to make it harder c. Decreasing the difference between the maximum and minimum stress values, as this effects the stress concentration factor d. Polishing to reduce surface defects e. Increasing its volume, to give a larger cross sectional area

Define what is meant by uniaxial, biaxial, and triaxial loading.