Transcript 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