Material Engineering

MATERIAL ENGINEERING вЂ" Assignment

Question :

PART A :

You as the mechanical engineer need to produce a connecting rod in the engine. Based on your knowledge of selection process and, list all the important factors using a flow chart.

Materials Selection and Design is a comprehensive reference on the basic concepts, methodologies, and information sources dealing with materials selection and its integration with engineering design processes. It makes the connection between design and materials engineering.

Material Design - Definition of Material Design

Material design is the process of tailoring material properties to meet the requirements of specific design problems2. Materials can be tailored or adapted to produce new materials with specific properties and performance levels. Material requirements detail the minimum material performance level necessary for a successful product design.

Material Design THEN

Materials have been discovered for centuries. The impact of new materials on civilization is evident in the naming of historical periods such as the Stone Age, Bronze Age, Iron Age, and Silicon Age. Ancient civilizations combined mud and straw to create bricks. Blacksmiths created stronger metals by adding carbon and adjusting tempering processes. Even within modern history, materials such as plywood and

Styrofoam have been created because of their desirable performance characteristics. Material design in the past consisted of a trail-and-error design method in which new materials were often discovered by chance.

Material Design NOW

In the fast-paced engineering design world of today, we do not have the time or resources to rely on trialand-error design methods to discover new materials. Research is currently being conducted in order to define a systematic design method for integrated product and material design. Materials are currently designed using techniques such as rapid manufacturing, product topology design, and functionally graded

materials.

Several examples of current materials design research are found below in Figure 3.

Material Design in the FUTURE

In material design of the future, engineers will be able to tailor the microstructure of materials in order to achieve specific material performance requirements. Material design will no longer be based on trial-anderror processes. In future material design processes, engineers will have a greater understanding of how the various length scales of a material (nanostructure, microstructure, mesostructure, ) affect the overall material performance. Interactions between the various length scales will be fully modeled and understood. As material design processes and techniques move towards perfection, scientists and engineers will be able to design a material to meet almost any performance requirement.

Material-Driven Design

Material-driven design describes a paradigm of incorporating materials in product designs. Materials are chosen based on availability, familiarity, or previous success. Materials are not tailor-made to meet specific design requirements. Historically, material-driven design was a very popular method of incorporating materials in the product design process when materials and engineering expertise were limited.

A flowchart describing material-driven design is presented below in Figure 5.

Under the material-driven design paradigm, product material and product requirements are known at the beginning of the design process. Based on the product material and product requirements, the layout and dimensions of the product are determined. By choosing the product material early in the design process, a significant portion of design freedom is lost at the beginning of product design.

Material Selection

Material selection is a method of using a material database to select the best material for product designs. By following materials selection techniques, the most appropriate material is selected from all known materials in order to satisfy product requirements and goals.

A flowchart describing material selection is presented below in Figure 6.

Ashby’s Material selection method. Figure 7

Among the material selection criteria are :

Material cost against strength.

Material strength against Density :

Material strength against elongation:

Material energy content against cost :

Material specific strength to specific stiffness :

And finally , Material toughness to strength :

In modern automotive internal combustion engines, the connecting rods are most usually made of steel for production engines, but can be made of aluminium (for lightness and the ability to absorb high impact at the expense of durability) or titanium (for a combination of strength and lightness at the expense of affordability) for high performance engines, or of cast iron for applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the con rod and the