Overview of Mechanical Properties and Testing

In Overview of Mechanical Properties and Testing, you'll learn ...

• Fundamental concepts of stress, strain, elastic and plastic deformation, and ductile and brittle fracture
• Different types of mechanical property testing procedures for metals, ceramics, polymers, and composites
• Tensile testing procedures, specimens, and measured properties
• Three-point and four-point bend testing procedures, specimens, and measured properties
• Hardness testing procedures, specimens, advantages, and disadvantages
• Impact toughness testing procedures, specimens, and concept of ductile-to-brittle transition temperature (DBTT)
• Industry standards for different mechanical property testing

Overview

Credit: 3 PDH

Length: 37 pages

Materials such as metals, ceramics, polymers, and composites are subjected to static and dynamic loads in service. Although these materials are all different, their characteristics that allow them to resist deformation and failure during loading must be known in order to make good design decisions, perform materials selection, and ensure quality. For example, the steel used in a car frames, the silicon carbide used in ballistic vests, the polyethylene (PE) used in food packaging, and the carbon fiber reinforced polymer (CFRP) composite used in sporting equipment are all defined by their characteristics or properties that in turn determines their ability to meet the requirements for the listed applications.

Many engineers require knowledge of mechanical properties and testing in order to ensure that undesirable deformation and failure in a component or structure does not occur. For example, civil and structural engineers must select steels with sufficiently high strength for bridges so that deformation does not occur. Similarly, an aerospace engineer must select an aluminum alloy or composite material that does not excessively deflect for use in a wing spar. A mechanical engineer may decide between stainless steels with different strengths for use in a corrosion resistant pressure vessel. On the other hand, ceramic, chemical, materials, and metallurgical engineers must understand mechanical properties, testing, and the appropriate standards in order to process and fabricate materials that meet the requirements of a specific application.

In this course, an overview of mechanical properties and testing is presented. The course first introduces the concept of stress and strain relevant for tensile testing. Testing of metals, ceramics, polymers, and composites is covered. For metals, ceramics, and polymers, each section starts with an overview of how the atomic structure influences mechanical properties and then discusses tensile testing and three-point and four-point bend testing in detail. In the case of composites, we first review the different classifications of composites and then discuss testing. For each class of material, the mechanical property test is discussed from the perspective of procedures, specimens, properties to be measured, and relevant industry standards. The stress-strain curve is covered along with differences between elastic and plastic deformation, and brittle and ductile behavior and fracture. In the next part of the course, hardness testing is examined for metals, ceramics, and polymers in context of procedures, specimens, advantages, and disadvantages. Testing from the perspective of industry standards is addressed. In the third part of the course, impact toughness testing is covered for metals, ceramics, and polymers. The important concept of ductile-to-brittle transition (DBTT) temperature is discussed. Tables of mechanical properties of some important engineering materials are included and equations relevant to each type of testing are covered in the course. A partial list of relevant ASTM industry mechanical property testing standards is included at the end of the course.