Basic Rules of Engineering Design

Basic Rules of Engineering Design

• Safe

• Simple

• Clear

Interrelationship Between the Safety Levels

Definition: Safety

Safety• is a state in which the risk is smaller than the risk limit

Risk limit• is the largest still acceptable system-specific risk relating to

a particular technical process or situation

Protection• is the reduction of risk by suitable means to reduce the

frequency of the occurrence or the extent of damage or both

Safety Aspects of a System

Aspects of Safety Technology

• Self-protection: product liability

• EC machinery directive : DIN EN 292; VDE 100; VDI 2244

• CE-Certification: declaration of conformity

• ISO 9001: document management; modification management; version management

Aspects of Safety Technology

Market acceptance:

• safe and environment-friendly products are received better by the market

• customers are prepared to pay more for safer products

• safety leads to a positive brand image: Mercedes, Volvo, Saab….

Safe Embodiment Design

Direct Safety Principles

Safe-Life

Important Measures:• Over-dimensioning of parts• Clear and simple embodiment design• Field-tests for determining the actual loads• Employ experienced interdisciplinary teams for

the development• Documented quality assurance over the

complete life-cycle• Inspection/maintenance

Example: Fail-Safe

Redundancy Principle

Indirect Safety Principles

Control of a Safety Fence

Aspects of Warning Safety Technology

• Lowest level of safety technology supplementary to other measures

• minimum measure when no other safety principle is applicable

• consider aspects of noticability and ergonomics

Warnings

Aspects Concerning Safety Data Sheets

• safety data sheets describe the danger potential of materials and substances

• the danger potential of materials and substances must be considered over the complete life cycle of a product:

• - production• - commissioning• - operation

• safety data sheets are a part of the product documentation

Material Aspect of Safety Technology

• The safety of a product can be increased by choosing a material that suits the operating conditions of the product

• Determining the operating conditions is crucial for the choice of materials:

• - corrosion resistant materials• - fatigue resistant materials• - materials that have a good adhesion to lubricants

Selecting Material Designed for Safety

The Nature of Principles of Embodiment Design

Aim of Principles of Embodiment Design

• The application of principles of embodi-ment design leads to products that are optimally designed – regarding the requirements taken into account!

Direct and Short Force Transmission Path

Direct and Short Force Transmission

Direct and short force transmission

Direct and Short Force Transmission

• Flowlines of force must always be closed

• Force transmission must be as short as possible

Avoid:

• deflection of forces

• discontinuous change of cross-section

• change of density of force flowlines

Direct and short force transmission

Idea of force transmission

Definition:The basic idea and illustration of force and moment transmission is taken from the field of fluid mechanicsSource:

Direct and short force transmission

Fundamentals:

• The flowlines of force should always be closed. (Inertial forces are not taken in to consideration)

• The stresses and strains change with in circular flowlinesof force.

• The flowlinesof force searches the shortest path

• The flowlinesof force come closer in narrow cross sectional areas.-On the other hand, they expand in broad cross sectional areas

Direct, Short Force Transmission: Welding

Direct Force Transmission: Bearing Pedestal

Direct Force Transmission: Relief Notches

Matched Deformation:Shaft-Hub Connection

• Principle of Balanced Forces

• Target:

• Reached by: system is free of forces to the outside

• symmetric structure of the system regarding the flow of forces