Chapter 1 Machine Elements

What are machine elements?

• Devices that generate electricity

• Basic parts that make up machines

• Software

Transmission elements are mainly used to:

• Support loads and reduce friction

• Transfer motion and power between machine parts

• Join two parts permanently

Why is the study of machine elements important for engineers?

• To design safe and efficient machines

• To replace software-based design

• To reduce the need for materials

Choose the correct factors that influence the design of a product?

• Function

• Stress/Strength

• Competitive

• Temperature

• All are correct

Name some common sources of uncertainty regarding stress or strength

• The material composition

• Properties variation

• load frequency

• Environmental conditions: temperature and humidity

• Inaccuracies in measuring

Select the correct names of some organisations that establish standards and codes of particular interest to mechanical engineers

• ASME: The American Society of Mechanical Engineers

• ISO: International Organization for Standardization

• AISI: American Iron and Steel Institute

• BSI: British Standards Institution

Give reasons why close tolerances generally increase cost.

• Additional processing steps

• Machines with lower production rates

• the product will be bad

Reliability, R: The statistical measure of the probability that a mechanical element will not fail in use.

• True

• False

If 1000 parts are manufactured, with 10 of the parts failing, the reliability is? (R=1-Pf)

• 0.994

• 0.97

• 0.990

A shaft with two bearings having reliabilities of 95% and 98% has an overall reliability of. R = R1 R2

• 0.93

• 0.97

• 0.99