1. Steve Lambert Mechanical Engineering, U of Waterloo
ME321 – Kinematics and Dynamics of Machines Design Process Notes (Continued)
Steve Lambert
Mechanical Engineering,
U of Waterloo
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2. Design Process
Preliminary Design – Product planning and clarifying the task (needs analysis),
Conceptual design,
Embodiment (layout) design, and
Detail (systems) design.
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3. Conceptual Design
Identify a number, usually 3, of conceptually different, viable solutions to satisfy the need
In order to be conceptually different, proposed solutions should be based on different physical principles
Each concept is refined to a sufficient level of detail to allow a fair evaluation of each concept so that the best one may be chosen
This is often difficult
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4. Creating Alternative Solutions
Copy other products – this is also useful to establish a baseline
Refine existing products – change scale, place in parallel or serial, etc.
Combine various existing elements
Inversion – ex., piezoelectric crystal
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5. Stimulating Creativity
Trial and error
Brainstorming
Analogy
Empathy
Morphological approach (parallel) – consider many solutions simultaneously
Systematic approach (serial) – subdivide the problem and solve separately
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6. Morphological Box
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7. Design Selection
Designs are selected based on their fit with design criteria
Selection process can be either quantitative or qualitative
The advantage of a quantitative scheme is that it can accommodate different priorities in your criteria through different weighting factors
The advantage of a qualitative scheme (+, -, or same as a reference solution) is that it does not accommodate different priorities numerically so that the designer is forced to argue each case as a whole
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8. Quantitative Design Selection
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9. Qualitative Design Selection
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10. Embodiment (Layout) Design
Takes design from the concept stage (sketch) to a layout drawing, which includes material specifications and geometry
Physical sizing and selection of specific components is done at this stage
This stage involves more detailed design calculations, required to select materials and geometry
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11. Embodiment Design Principles
Separate functions
Provide a direct and short transmission path
Do not over-constrain a component, but provide sufficient constraint
Match impedance or eliminate gradients
Provide functional symmetry
Design for self-help
Design for fail-safe
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12. Detail Design
Involves the individual design or specification of components such as beams, trusses, connections, shafts, bearings, etc
Often requires detailed analysis of your component and/or assembly using FEM or CFD, for example
Often involves the production and testing of physical or software (solid model) prototypes
Testing is intended to identify possible problems before production
Changes to the basic configuration should not occur at this stage, only a refinement
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