27.7 STRESS CONCENTRATIONS

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À  p

Saint Venant's Principle states that regardless of how a force is applied, when we move far enough away, the distribution becomes even. For example, if we are applying forces as point loads, they will have very high stress concentrations near the point of application. But, as we move away from the point of application, the force distribution evens out. Consider the pin in the hole where the pin applies a load of P.

Stress concentrations are hard to predict, and this must often be done using experiments, Finite Element Analysis (FEA), or other techniques.

During design we must pay attention to the stress concentrations. At some points the stress will be higher that the average stress.

One technique for estimating maximum stress concentrations is to use tables derived experimentally.

Consider the sample problem below,