Language
Country/Area
No result found
The magic formula in design: How to use material index to improve your product performance?
Material selection is an important step in the process of designing any physical object. In the context of product design, the primary goal of material selection is to achieve product performance goals at minimum cost. Systematically selecting the best material for a specific application starts with considering the performance and cost of the candidate material. Material selection can be greatly aided by the use of material indices or performance indices, which are related to the desired material properties.
For example, thermal blankets must have good insulating properties to minimize heat transfer at specific temperature differences.
Designers must fully understand the properties of materials and their behavior under operating conditions. Some important material properties include: strength, durability, flexibility, weight, resistance to heat and corrosion, castability, weldability or hardening, machinability, and electrical conductivity. In contemporary design, sustainability becomes a key consideration in material selection. As environmental awareness increases, professionals begin to prioritize factors such as ecological impact, recyclability and full life cycle analysis in their decision-making processes.
Challenges in material selection
Systematic selection becomes complex in applications that require multiple standards. For example, when a material needs to be both stiff and lightweight, for a rod a combination of high Young's modulus and low density presents the best material, whereas for a plate the bending stiffness of the plate is usually related to Thickness is proportional to the cube, so the cube root of thickness divided by density is the best indicator. In the same way, considering the requirements of "stiffness" and "lightweight", if you want to cope with tension-loaded rods, you should consider the ratio, dividing the modulus by the density.
Reality often has limitations, so practicality considerations must be taken into consideration. The cost of ideal materials, depending on factors such as shape, size and composition, may be prohibitive.
Ashby diagram and cost considerations
The Ashby plot is a scatter plot named by Michael Ashby of the University of Cambridge that shows two or more properties of a variety of materials or classes of materials. These graphs are useful for comparing ratios between different performances. Cost plays a very important role in material selection. The most intuitive approach is to develop a monetary metric for the material properties, for example, a life cycle assessment could show that the net present value of reducing the weight of a vehicle by 1 kg is approximately $5.
For commercial aircraft this figure is closer to $450/kg, while for spacecraft launch costs are around $20,000/kg, so these factors dominate the selection decision. As energy prices rise and technology advances, automobiles gradually replace steel with lightweight magnesium and aluminum alloys, and aircraft use carbon fiber reinforced plastics and titanium alloys to replace aluminum and other materials.
How to apply Ashby diagram
Utilizing Ashby diagrams is a common method of selecting appropriate materials. First, three different groups of variables need to be identified: material variables, free variables, and design variables. Material variables are intrinsic properties of the material, while free variables are quantities that change with loading cycles, such as applied force. Design variables are constraints on the design, such as the thickness of the beam or the maximum deflection of the beam.
For these variables, we need to derive an equation for a performance index that quantifies the desirability of a material in a given situation.
Examples of optimal material selection
In a practical situation, when a material is faced with both stretching and bending, an ideal material would have to be able to perform well in both situations. By creating corresponding Ashby plots and calibrating them for all known materials, the most suitable material can be easily selected.
Ultimately, with the improvement of material performance index, the selection of high-performance materials is no longer a simple process, but needs to consider the balance between cost reduction and performance optimization. Every material choice will greatly affect the performance and sustainability of the final product.
In product design, are you ready to explore these material exponents to improve your product performance?
