How is safe working stress determined?

Safe working stress is determined by dividing the ultimate strength of a material by the factor of safety. This approach ensures that structures and components are designed to withstand expected loads without failing. The ultimate strength is the maximum stress a material can handle before it experiences failure, typically measured in terms of tensile or compressive strength.

In engineering practices, a factor of safety is applied to provide a margin for uncertainties in material properties, loading conditions, and potential flaws. By using this method, engineers can account for these uncertainties and ensure that the materials are not stressed beyond their capacity in real-world applications, resulting in safer designs.

The other methods listed, such as interpolation and extrapolation, refer to techniques used for estimating values within or outside a range of known data points, respectively, and do not directly relate to determining safe working stress. Multiplying the ultimate strength by strain does not represent a valid method for calculating safe working stress, as it misunderstands how strength and stress relate to material deformation. Therefore, using the ultimate strength divided by the factor of safety is the standard and accepted practice in the industry.