What is meant by material selection?

A wide variety of engineering applications make use of different materials, depending upon their usage. The materials used in civil engineering vary in their properties such as strength, ductility, brittleness, and creep strength. Depending upon the application and external loading conditions, an engineer must make a wise decision for material selection. A wrong decision would fail in its functionality.

Material selection is the primary step towards a designing process in every engineering domain. Various factors such as loading conditions, environmental conditions, elasticity, creep behaviors, coefficient of thermal expansion, and so on, should be factored in by the engineers while selecting any material for any application.

For additional reading and to gain knowledge regarding cutting-edge researches in this field, it is advisable to refer to scientific journals such as the International Journal of civil engineering and Journals of materials in civil engineering.

Material selection based on applications

Type of structure

The material selection in this category greatly influences the type of building and type of structure that an engineer builds. If the structure is intended for load-bearing purposes, choosing a high-quality brick is the best option, as bricks are the foremost load-bearing materials in building construction. For supporting framed structures, strong concrete foundations materials are the best selection.

Based on performance

This material selection category depends on the requirements of a building or features that the people inside the building need such as durability, heat resistance, soundproofing, and weight reduction. For tall buildings, the weight reduction at higher floors is the primary requirement, so selecting low thickness bricks is important. For residential buildings and libraries, engineers generally select bricks having sufficient thickness that aids in soundproofing.

Cost

Cost reduction is the primary concern in any manufacturing process, so sufficient emphasis is given to selecting the most cost-efficient material that provides the best functionality with minimum maintenance requirements.

Material availability

Before starting a project, engineers must ensure the availability of materials. Emphasis should be given regarding the availability of materials in the local area while a selection of materials, will reduce the transportation costs.

Climate

Climate is the most important in the material selection process. Buildings that are to be constructed in areas having little sunlight, as in most of the European countries, engineers use glass claddings at the outer periphery to bring in more sunlight. For buildings present in areas with heavy annual rainfall, bricks with very low permeability should be used.

Environmental concerns

Small residential buildings made with wood play a major role in harming the environment, as a large number of trees have to be cut down to meet the construction needs including aesthetics.

Material selection based on material properties

The next major selection lies in material properties after the application of the building has been planned. The various material properties that affect material selection processes are outlined below,

Strength

Engineers choose the right material based on the strength criteria and applications. When it comes to strength, the metals provide the best strength properties to use in most structural applications. When it comes to load-bearing structures and building foundations, the materials need to have excellent strength properties. To achieve that, engineers select the right candidate materials for concrete compositions and the right metals for the reinforcements. A beam in the other sense must have good flexural strength to withstand the deformations caused by loads of the building itself. Tall skyscrapers undergo deflection and twisting due to different modes of vibration-induced due to seismic loads. Hence, the material used must have good torsional strength or modulus of rigidity with excellent flexural strength.

Corrosion resistance

The primary component of the framed structures is metals. Engineers must choose suitable components for structural applications. The structures withstand harsh environmental conditions such as humidity and rainfall, so the metals must possess good corrosion-resistant properties.

Fatigue strength

Structures in high-temperature areas undergo frequent expansion and contraction. In long term, this leads to the development of cyclic stresses. These materials are prone to crank imitation and propagation. Incorrect material selection along with engineering design leads to fatigue failure. Also, before subjecting the materials to practical use, an in-depth fatigue test of the individual materials is very important in the early stages of engineering design.

Machinability

The materials to be used for engineering applications should possess good machinability; this property alloys the workers to cut and machine the materials to suit the dimensional needs.

Material selection for product design

Product design is the creation of products from scratch to a functionally meaningful system, which can be specially used by the users. There are a plethora of material options available, but all of them depend on the purpose and type of functionality. A product such as a medical device is primarily made up of thermoplastics such as polylactic acid (PLA) and Acrylonitrile Butadiene Styrene (ABS), as they can be easily molded to any shape. Products such as mobile smartphones implement both plastics and metals, but the selection of metals should be such that it does not contribute to the weight of the device; it should also provide better functionality. Going for materials such as aluminum is a good choice for such devices.

Other products such as cutting tools in engineering applications require must have high wear and temperature resistance. These tools must also have excellent strength properties. Material such as high-speed steel (HSS), solid carbide, and diamond coated tools are the best for machining applications such as turning, milling, and drilling. These tools aid in piercing through some of the toughest metals and concrete.

Context and Applications

The topic has its practical application in most of the civil engineering applications that deal with construction works. The topic is a forefront research area for many doctoral and post-doctoral degrees in the US and abroad.

Besides, the topic is extensively taught in many undergraduate courses such as bachelor of science, specialized in mechanical engineering, material science and engineering, and civil engineering.

• Bachelors of Technology in Civil Engineering
• Bachelors of Technology in Chemical Engineering
• Masters of Technology in Civil Engineering
• Masters of Technology in Chemical Engineering

Practice Problems

1. Which of the following is an important property for a framed structure?

1. Ductility
2. Creep strength
3. Performance index
4. Corrosion resistance

Correct option- d

Explanation: Framed structures are mostly composed of metals that are subjected to harsh environmental effects such as moisture and rainfall. Under such conditions, the metallic components must possess good corrosion resistance properties.

2. Which of the following is a building construction material?

1. Thermoplastics
2. Wood
3. Concrete
4. Both b and c

Correct option- d

Explanation: Wood and concrete both are building construction materials used in civil engineering applications.

3. Which of the following is the property of a material that allows it to be machined to meet dimensional needs?

1. Tensile strength
2. Compressive strength
3. Creep strength
4. Machinability

Correct option- d

Explanation: An engineering machineability must possess a good machinable property that allows works to cut the material and perform suitable operations to bring the material to the necessary dimension and geometry.

4. In which of the following areas, glass claddings are used?

1. Areas with high temperatures
2. Areas with low temperatures
3. Areas receiving low sunlight
4. Areas receiving more sunlight

Correct option- c

Explanation: Glass claddings are primarily preferred in areas receiving low sunlight, as in European countries. These claddings permit more sunlight to enter the building.

5. Which of the following is a civil engineering journal?

1. Edu pack
2. International Journal in Civil Engineering
3. Journal of Materials in Civil Engineering
4. Both b and c

Correct option- d

Explanation: Journal of Materials in Civil Engineering and International Journal in Civil Engineering, both are high-quality civil engineering journals that one must prefer for additional knowledge and to get an insight into the cutting edge research in the civil engineering domain.