DETERMINING IF FORCE AND/ OR MATERIAL TESTING IS RIGHT FOR YOUR APPLICATION
The majority of product testing in manufacturing environments requires the force measurement of samples to verify if they are able to withstand specific load application during post-production. However, throughout the product design and development stages, material properties are also tested and studied to determine if and how the material is an applicable fit for the product. There is a distinction between these two types of tests – Force Measurement and Material Testing – and your choice can be simplified by knowing what kind of information you need to collect. The Difference in Units First, it is helpful to understand the difference in units. Force testing measures the sample’s ability to withstand or fail under an applied load. These loads are commonly measured in values of pounds-force (lbf) or newtons (N), while height or travel is measured in distance units such as inches (in) and millimeters (mm). Material testing replaces the values of load and travel for stress and strain, which are typically measured in pounds per square inch (PSI, or lbf/in^2) or MegaPascals (MPa, or N/mm^2) for stress, and as a fraction or percentage for strain. The key difference between these two-unit sets is that stress and strain are determined from properties of the material sample itself, rather than just the load being applied. Consider breaking a cube in half in a uniaxial force tester operating in a perfect system where objects don’t deform under tension. The test is designed to hold the sample by opposing faces, applying a tensile force to break it in half. The resulting halves would be perfect square prisms, each half the height of the original cube. A force test assumes that the size and shape of the cube is irrelevant – either because all of the cube samples are uniform in dimension so that
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the size and shape would not matter, or the difference in sizes are unimportant as long as the cube reacts properly to the loads being applied. As a result, it would be unnecessary to test in values of stress and strain and instead measure in load and distance. Common Units in Test Graphing Based On Testing Type
X-Axis
Y Axis
Newtons (N), Kilonewtons (kN), Gram-force (GF), Pascals (Pa), Megapascals (MPa), Pounds per Square Inch (PSI)
Force Testing
Millimeters (mm), inches (in)
Material Testing
Unitless, or a Percentage (%)
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