The Load Cell

The load cell is a force measuring device. Typically load cells are used in testing machines similar to the one we use for our tensile test. Weight is usually measured using springs. The load cell is nothing but a giant spring. The springs used in balances can measure small forces or weights. The load cell is made out of high strength material and is capable of measuring large forces.

Figure 12: The load cell used in the tensile testing machine.

The applied load induces a strain on the side face of the load cell (you will later learn how to numerically calculate the strain given the material properties of the load cell and the applied load). This strain is then converted into an electrical signal that can either be fed into a computer or displayed. The load cell is usually designed to be operated in the linear elastic region. Such a response of the load cell is as shown in the right of Figure 12. Once the slope $s$ of this linear line is computed, the load cell can be used to measure the strain and with the strain the applied load can be calculated using this slope.

Figure 12a: The load cell converts the applied strain that can be displayed.