Lec.7 Performance Indices and property (Ashby charts) by Dr. Ahmed Ameed 3 Performance (Merit Index): is a grouping of properties which, when maximized, give some maximum performance of a material. When designing something, we often have particular objectives such as minimum weight or maximum stiffness. There's software that helps choose new or substitute materials for a product. This Ashby chart in Granta CES Selector plots the mass against the cost per unit-of-strength of. The tools Material selection charts are a key tool in CES Selector.

A unique PC-based software product supporting systematic selection of materials for engineering applications. CES Selector, based on the Cambridge Engineering Selector (CES) approach developed by Professor Mike Ashby at Cambridge University, is a unique tool for the rational selection of engineering materials – metals, ceramics, polymers, composites – and of manufacturing processes – shaping, finishing, joining, and surface treatment. The software is easy to install and use on your PC. It combines a database of materials and process properties (choose the Edition to fit your needs) with software tools to: * Browse and search the information in the materials property database * Create highly visual, interactive materials property charts that enable you to inspect and compare materials, and * Apply this information using a systematic materials selection method to identify and rank the best materials for a particular engineering application.

Selecting materials requires data. Material properties can be found in books, journals, on-line databases, and directly from colleagues, consultants, and material suppliers. Unfortunately, these methods are often time-consuming, don’t necessarily lead to the best materials, and new materials frequently get short shrift. Also, data about a material can be. slanted: Material suppliers often present best-case scenarios for their materials or will quote material properties relevant to their target markets.

CES Selector from Granta Design Ltd. () helps with all this.

The software program assists in making the initial cut for selecting materials for new products. It’s also good for finding substitute materials in existing or redesigned products. The software combines a database of materials and process properties with an array of wizard-style tools for searching the database, displaying interactive and intuitive charts and tables to compare materials, and ranking materials for an application (read: product design). The methodology CES Selector applies a systematic method to materials selection. Developed by Professor Mike Ashby at Cambridge University, the methodology optimizes material choices based on the tradeoffs in material performance and costs. The methodology accounts for the function, objectives, and constraints (including manufacturing) of the design under consideration.

For instance, as explained on the Granta website, “a car body panel (function) needs to be as light as possible (objective) for a specified stiffness and cost (constraint). Other constraints on the design might be acceptable resistance to mechanical impact and contact with various environments.” At the core of Granta’s software is a database of all classes of materials, called the “Material Universe.” Users can find and review datasheets about the materials of interest, and then drill down for more information about individual material grades, specifications, and performance. Material Universe covers all classes of engineering materials, including polymers, global standards and designations for metals, composites, natural materials, and ceramics.

What sets Material Universe apart from other materials databases is that its data is comparable; Granta essentially normalizes the properties data across suppliers and test techniques. That said, the cost data in CES Selector is not accurate enough for the cost estimates required for bidding or calculating profit-and-loss. Nor is the software intended for that purpose. Instead, CES Selector is basically a pre-screening tool for selecting materials early in product development.

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At this stage, says Charlie Bream, Granta’s CES Selector product manager, engineers are looking first for large differences in performance, second at tradeoffs-versus-costs. This is especially true when looking at different classes of materials. For example, the material properties and performance for a glass-filled polyamide and a specific aluminum alloy will be very different—even though the two materials might be suitable for a particular design. “Obviously, once you’ve identified a material that is good, you need to contact suppliers, get samples, and carry out your normal material-qualification process,” continues Bream. “CES Selector isn’t about replacing material testing and characterization. That still needs to be done. Rukovodstvo po ekspluatacii lifta schlz. But it is very much about letting you quickly identify the material that shows promise in your application.” The tools Material selection charts are a key tool in CES Selector.