In physics, a force is any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape. The SI unit (International System of Units) for Force Measurement is the Newton. This is the force required to accelerate a one kilogram mass at a rate of one meter per second squared. The corresponding CGS Force Measurement unit is the dyne, the force required to accelerate a one gram mass by one centimeter per second squared. The English unit of Force Measurement is the pound-force, which is defined as the force exerted by gravity on a pound-mass.
Sensor Products distributes several products for Force Measurement. One of these is a Force Sensing Resistor. Its resistance changes when force or pressure is applied. (See Figure 1.) More information on the Force Sensing Resistor can be seen by clicking the link. A second Force Measurement device is the Shear Sensor that is shown in Figure 2. This sensor performs Shear Force Measurement. The 2-in × 2-in sensor has 16 sensing points in a 4 × 4 array, and it performs Force Measurement between 0 and 1.5 N. Click the Shear Sensor link for more information. Another Sensor Products device for Force Measurement is the Tactilus® Flex Sensor. (See Figure 3.) This device deflects in response to a bending moment. The extent of the deflection is proportional to the force of the bending moment. See the Tactilus® Flex Sensor link for more information on this product.
Fig 1: An Array of Four, Force Sensor Resistors
Fig 2: Picture of a Shear Sensor Used for Force Measurement
Fig 3: Tactilus® Flex Sensor Bending Moment Response
Another approach to Force Measurement is the use of Fujifilm Prescale® Tactile Pressure Indicating Sensor Film to measure pressure between objects and then calculate the applied force from the pressure result. This approach was taken by researchers from the University of Applied Sciences Technikum Wien in Vienna, Austria. Their published work is, “Construction of a Test Bench for Bicycle Rim and Disc Brakes,” BSc Clemens Oertel, DI Heinz Neuburger, FH-Prof Ing MMag Dr Anton Sabo, Procedia Engineering 2 (2010) 2943–2948. Figure 4 shows the Force Measurement results from this study.
Fig 4: Handling Test of a Disc Brake Model with Three Different Disc Diameters. The hand force was calculated using results from Fujifilm Prescale® tests.
Additional information on Force Measurement can be found in the following links: Tactilus®, Tactilus Free Form® Sensing System, and Tactilus® Nano-Polymer Core H Series Sensor. Glossary terms relating to Force Measurement include the following: Bolted Joint Force, Compression Force, Surface Force Mapping, Surface Force Pressure, and Surface Force Profiling.