2 lecture 4 - Failure Predictors and Safety Factors - slide

For a given mode of failure the designer will answer

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: BICYCLE SPOKE Question: How can it fail? Mechanical Design When listing possible failure modes, engineering designers are concerned with the question: How will it fail? For a given mode of failure, the designer will answer the question: When will it fail? The designer must be able to predict the circumstances under which a particular mode of failure will occur. To make this prediction, designers often need to use Failure Predictors: • mathematical models of how stresses combine to cause failure by yielding or fracture • often called “theories of failure” Question: Why do engineers need failure predictors? Mechanical Design Prediction of failure by yielding Case study #1 – bicycle spoke Essentially uniaxial tension. P Uniaxial stress: σ1 Question: When will it fail? σ1 = P / A P Mechanical Design Prediction of failure by yielding Material laboratory testing Determines material strength properties Performed under UNIAXIAL TENSION conditions test conditions experimental results Mechanical Design Aluminium Prediction of failure by yielding Steel Material laboratory testing SU Determines material strength properties Performed under UNIAXIAL TENSION conditions Aluminium test conditions Sy experimental results Typical experimen...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online