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Systems and components must be tested before the final commissioning to ensure that they will function per design during their lifespan. The quality of the entire system is directly related to the performance of the components. Thus, systems with little to no tolerance for failure must be tested to the limits.
Destructive testing is the process of evaluating the strength, durability, and performance of materials, by subjecting them to extreme conditions that eventually cause their failure. Knowing the failure point of a system enables designers to know the safe working conditions of the said system. In this article, we will discuss some of the most common destructive testing methods used in various industries.
Tensile Testing
Tensile strength is a measure of the amount of stress a material can withstand before breaking or deforming permanently when subjected to tension. In other words, tensile strength is a material’s ability to resist being pulled apart by opposing forces acting along its length.
Tensile strength is a unique property, meaning that it differs from material to material. However, the tensile strength of a component also depends on the diameter/thickness and medium temperature. Materials that are expected to endure tension during their life span must be measured for their tensile strength, in the same condition that they will endure in nominal working conditions.
The test is conducted by preparing a sample of the material in the form of a thin strip which is then placed in a tensile testing machine. The machine applies a gradual load until the sample breaks. The test results show the material’s ultimate strength, yield strength, and elongation at failure.
Bend Testing
Ductility is the ability of a material to deform without breaking when subjected to tensile stress or strain without breaking. It is a crucial quality in many technical applications, such as in the fabrication of wires, cables, and other items that require a high degree of flexibility and durability.
With bending testing, the ductility of the material is tested. A sample of the material to be tested is prepared in specific dimensions. Afterward, the sample gets bent to a predetermined angle until it fractures. The test results provide information on the material’s bending strength, ductility, and fracture toughness.
Impact Testing
Impact testing is a method of assessing the strength of materials under sudden impact. The test measures how well the material can absorb energy and resist fracture or deformation.
The impact test is used to measure the material’s resistance to deformation by the impact. The force and velocity of the impact are controlled and recorded, and the resulting deformation or fracture is analyzed to determine the material’s toughness.
Automotive and aerospace components are expected to endure surface impact during their lifespan. Thus, impact testing is commonly used in, the automotive, and aerospace industries.
Fatigue Testing
Have you ever tried ripping a thin metal wire off by thugging it from opposite sides? For most of us this is impossible but, bending the wire up and down continuously breaks it after a few cycles. This is the result of fatigue. Materials that have immense amounts of tensile or bending strength can deform under lesser amounts of force than their limit values.
Frequent loading and unloading are extremely dangerous therefore, systems and components which are expected to work under fatigue must be tested to know safe working conditions. Thus, fatigue testing is a crucial tool for both engineers and designers.
Hardness Testing
Surface hardness is a critical material property for various industries. It is the ability of wear, tear, and deformation resistance. It is an exceedingly important property for certain industries. Machine and kitchen equipment manufacturers utilize materials with the surface harness to ensure a quality product.
Hardness testing can be determined by three different types of testing; Brinell, Rockwell, and Vickers. Even though the methodology and the evaluation are different, all tests are conducted the same way. A sharp edge is pressed into the surface to measure the depth it goes in under a specific amount of pressure. The depth which the pressed edge creates is used to evaluate the hardness of the material.
Compression Testing
Resistance to compression is another extremely important material property, especially for the construction industry. Steel, wooden or concrete beams get compressed toward the foundation, carrying the entire weight of the building. Thus, the materials which will be used to create load-bearing constructive components must be tested for compression testing. Compression strength can be thought of as the opposite of tensile strength which is a material’s capacity to withstand inwards pressure from both endings.
Testing material for compression strength is also the opposite of tensile testing. A sample of the material is pressed usually via a hydraulic press. The amount of pressure that causes disposition and the final breakpoint is measured to assess the compression resistance of the material.
Final Words
Designing safe systems depends on the limits of the materials. Destructive testing methods allow designers and engineers to test materials to their limits. Knowing the limits of materials allows for safer design under optimal conditions.
