Durability analysis 101

Structural components such as a steering knuckle might be strong enough to withstand a single applied load. But what happens when the part operates over and over, day after day? To predict component failure in such cases requires what's called fatigue or durability analysis. Computer simulations determine how well parts will hold up during cyclic loading. Results are important in calculating and verifying safe part lifetimes. In the past, durability analysis was largely the province of research. For starters, processes that cause part failure are complex. They involve progressive material changes, often highly localized, that end in cracks or complete fracture. For an introduction to durability analysis, it's helpful to start with a few basics. First, because failure is progressive, time is an important element of design. And because failure is localized, it's necessary to understand local stresses. For our purposes, a constant or