Lab 9: Stress and Strain Measurement and Analysis - Prof. Anthony Duva, Lab Reports of Mechanical Engineering

Lab 9- Stress and Strain

Introduction

One critial, primary, must-satisfied design criteria for mechanical engineering is that the

actual stress in part or components during operations must be less than allowable stress specified

by the design engineering. The allowable stress of the materials is generally specified by the

material manufacturer and is a known variable for design engineers. The key issue is how to

find out the actual stress of the components.

Generally, three approaches are equally used in mechanical engineering, which are

theoretical prediction (calculation), finite element analysis (FEA) and strain & stress

of the actual stresses and use these as a starting point.

Finite element analysis (FEA) is a very powerful tool for predicting the sctual stresses,

which is a numeraical techniques and acquire to use computers, which is one of common tools

availabe for every design engineering. FEA can deal with very complicated geometry and

loading conditions. FEA can also provide relative accurate results acceptable by mose of design

engineers supposed that loading conditions, boundary conditions and initial conditions are

correctly considered.

In reality, both the theroretical prediction and FEA results of the actual stress of the

compoments must be verified by testing if components are critical components in the machine

or equipment. If the testing is properly carried out, the testing results will be results design

compared and discussed.