Materials Properties in Ski Design

Engineering Design and Material Selection

• Lecture 10 focused on materials and their properties
• Course schedule outlined topics, case studies, quizzes, and lecturers for each week.
• Week 10 covered material properties and the relationship to additive manufacturing.
• Learning objectives covered categorization of materials into families, understanding mechanical behavior, relating stress and strain via material laws, and exploring bending behavior.
• A case study on ski design was presented.
• This included a function of force transmission from the body to the ski, requirements to withstand environment forces, bend at a desired level, provide torsional resistance, reduce vibration, turn easily, resist environment temperatures and wear.
• Ski design is a compromise of design variables to match skier's weight, technique and use.
• The different layers of a ski were depicted to show the different material layers.
• An overview of design dependencies detailed function as a task independent of solutions, dependencies such as shape, size, and features are needed to fulfil a function.
• Functions require specific material properties (e.g., material elasticity and thermal properties).
• Material choice and target shape interact with the manufacturing process
• Manufacturing process influences the design function by changing part properties
• A history of material shapes technology was discussed.
• The history of material technology, along with the future of materials in engineering designs was addressed.
• This included discussion on "Floating Steel," "Artificial Tree", and "Multi-Material Designs"
• A vast choice of material was visually represented, showing different materials like metal, polymers, glass, and ceramics.
• Material families were categorized and described including metal, glass, hybrids, polymer, and ceramic.
• Key properties of materials were listed, such as stiffness, strength, and brittleness.
• The importance of engineers having a common language when selecting materials was highlighted.
• Lecture noted the mechanical, thermal, electrical, optical, magnetic, chemical, economic, and ecological properties of materials.
• The importance of mechanical properties, for ensuring the integrity and safety of products, was highlighted.
• The relationships between forces and deformation in a body were described through diagrams.
• The different behavior of materials in different shapes (e.g., ski vs. snowboard) was explained.
• Stress and strain were defined in terms of force/area, and deformation to initial configuration respectively.
• Basic equations for Young's modulus were presented, allowing calculation of safety against failure.
• Material testing was explained as a way to determine the stress-strain curves in materials.
• The importance of stress-strain curves and Hooke's Law was presented in terms of linear elastic behavior.
• The spring analogy of Hooke's Law explains the relationship between force, elongation and stiffness.
• The concept of bending and torsion were explored.
• Flexural rigidity and the second moment of area were defined within the context of three-point bending tests.
• Different properties of materials in relation to bending stiffness and distribution across skis were explored.
• Case study questions related to ski bending, identifying parameters for ski design.
• Methods for calculating deflection in skis were detailed.
• Material Selection and their Properties explained how category, material, function, and properties are related to sustainable design
• An overview of Life Cycles and Materials including renewable, non-renewable, inorganic, organic materials, and identifying toxins
• Exercises explained how to find Young's Modulus for a sample.
• Overview discussion of material selection strategies included topics like translation, screening, ranking, and validation.
• The design process for selecting materials, involving stages like planning, concept design, and system level design, detail design, were presented along with the phases for evaluation, verification, and refinement, and concluding with production or ramp-up.
• A general approach involved translating requirements into design objectives, evaluating the limits (constraints), and producing a ranked list of material options.
• Computer-aided material selection software, allowing evaluation of various materials and their properties using a variety of 2 dimensional and 3 dimensional plots, was discussed, including example diagrams.
• Design heuristics for additive manufacturing (AM), presented in 8 categories, were discussed.
• Additional design considerations for AM included the importance of part consolidation, material distribution, and embedded/enclosed geometries.
• An example case study on ski bending included considerations for the functions, technical, and material requirements, along with constraints, objects, and free variables.
• Design guidelines for machining to improve manufacturing were stated.
• Different manufacturing processes for various purposes (castings, molding) and materials were mentioned.
• Additive manufacturing (3D printing) processes were presented.
• Isotropy and anisotropy of material properties were distinguished.
• The advantages and disadvantages for manufacturing using various methods (machining, casting, and additive manufacturing) were examined.
• Topics like process selection strategies, including steps in screening, ranking and validation were detailed.
• Additional topics focused on processes selection strategies involving compatibility matrices, and methods for economic batch size analysis were presented.
• The process of designing for manufacturing (DfM) was detailed as a convergent method that focuses on the relationship between the design process steps of manufacturing.
• Manufacturing processes for material selection strategies, involving examples such as turning and the cost analysis when considering batch sizes were explored.