Chapter 2 Principles of Machinery Design Key Terms: strength rigidity failure mode criterion stress allowable factor of safety

Outlines Fundamental Requirements for Machinery Design Failure Modes of Mechanical Components Design requirements for Mechanical Components General Criteria for Component Design

2.1 Fundamental Requirements for Machinery Design Functional Requirements Safety and Environment Requirements Reliability Requirements Economic Requirements Other Specific Requirements

2.2 Failure Modes of Mechanical Components

1、Fracture 2、Plastic Deformation & Elastic Deformation 3、Surface Damage: Wear Corrosion Pitting Glue 4、Abnormal Operational Condition: Slip 打滑

fracture

plastic deformation

glue

Pitting

wear

2.3 Design Requirements for Mechanical Component Design for Safety 1) strength 2) rigidity 3) working life Design for manufacturability Design for Costs Design for Reliability

2.4 General Criteria for Component Design Strength Criterion Rigidity Criterion Wear Criterion

Dynamic Criterion Reliability Criterion Safety Factor

2.5 Methods of the Machinery Design Traditional Design Methods Theoretical Design Empirical Design Model Design

Modern Design Methods CAD (computer–aided design) FEM (finite element method) OD (optimization design) RD (reliability design)

2.6 Materials in Machinery Design Carbon steels Alloy steels Cast irons Copper、Aluminum Plastics Composite materials

2.7 Standardization in Machinery Design Benefits: • Ensure interchangeability of components; • Permit convenient manufacture with standard machines and tooling.

Classification: ISO GB QB

The end Thanks!