Force Transducers and Load Cells [N]

The Wheatstone bridge circuit is used, for example, in force measurement to measure electrical resistance changes of strain gauge-based force sensors. It allows to measure smallest resistance changes with high accuracy. Since high accuracy requirements usually have to be met in strain gauge transducer design, full bridge circuits are usually used. 

Since the quantity determined in the force transducer according to Newton's 2nd axiom is F=m*a, i.e. the product of mass m and its acceleration a, this can have an enormous error influence on the result of dynamic force measurements, although the force transducer functions almost error-free in static applications. Be sure to take this aspect into account when designing your force measurement application.

Temperature behavior plays an important role in strain gauge-based force sensors. In practice, two technical characteristic values of the force transducer must be taken into account. The temperature coefficient of the characteristic value (TKC) and the temperature coefficient of the zero point (TK0). With the selection of high-quality materials, suitable strain gauges, additional electronic components and a sensible bridge circuit, the influence of the temperature behavior of force transducers can be reduced to very low characteristic values.

The introduced force must act as accurately as possible in the measuring direction of the force transducer. Furthermore, special attention must be paid to a sufficiently stiff contact surface. Changes in the force introdcution, even the slightest deviations of the force introduction point in the force introduction surface, therefore lead to differences to the specified parameter. When designing the application, it is important to ensure that other components such as off-center loads, transverse forces or torsional moments are prevented or minimized as far as possible, since these disturbance variables can lead to falsification of the measurement signal or, in the worst case, to irreversible deformation of the force sensor. 

Depending on the application and the forces to be measured, the selection of the force sensor design can vary. GTM offers force transducers with (1) bending ring principle (force transducer series K), (2) bending spokes (force transducer series K), (3) bending beam (force transducer series KL), (4) shear beam (force transducer series DR) or (5) longitudinal and transverse strain in the tube (force transducer series RF). The design and the force transducer material used are, in addition to the nominal force, determining boundary conditions of a force sensor.

In some force measurements it may be necessary to equip the force sensor with mechanical accessories. By means of mechanical GTM adapters, GTM force transducers can be optimally integrated to the respective metrological task. Mechanical mounting accessories such as base plates, thrust pieces form an inseparable systemic unit to achieve precise and reliable measurement results with GTM force sensors. Therefore, we offer the appropriate and wide range of mechanical accessories also according to ISO376 for a broad spectrum of demanding applications. 

Measuring cables and the associated plugs and sockets are a particularly important part of the entire force measurement, because they have a significant influence on the accuracy of the measurement result with our force sensors. Depending on the application, robust or high-precision measuring cables are the appropriate choice. You can find detailed information here -> https://www.gtm-gmbh.com/en/products/accessory/connecting-cables

• The strain gauge (SG) technology used for GTM force sensors is considered proven and cost effective. 
• GTM force sensors are characterized by high accuracy and excellent linearity and hysteresis behavior. 
• The robust design of the GTM force transducers enables multivalent usability and many degrees of freedom for mounting in a wide range of applications and industries. 
• GTM force sensors are ideal for measuring static and dynamic force measurement applications. 
• The special design of the GTM force sensors ensures high resistance to parasitic forces or moment influences. 
• GTM force sensors feature very good temperature compensation due to intelligent interconnections of the strain gages and supplementary elements to form a Wheatstone bridge circuit. 
• GTM force sensors are characterized by high continuous load resistance due to the use of high-quality materials. 
• GTM force sensors have outstanding long-term stability, making them a sound investment in your overall application.