Force Transducers for Maximum Precision

The Wheatstone bridge circuit is used, for example, in force measurement to measure electrical resistance changes of strain gauge-based force sensors. It allows the smallest changes in resistance to be measured with high accuracy. As strain gauge transducers generally have to meet high accuracy requirements, full bridge circuits are usually used.

Since the value 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 influence on the result of dynamic force measurements, although the force transducer functions almost faultlessly in static applications. Be sure to take this aspect into account when designing your force measurement application.

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

The applied force must act as precisely as possible in the measuring direction of the force transducer. Furthermore, particular attention must be paid to a sufficiently rigid contact surface. Changes in the force application, even the slightest deviations of the force application point in the force application surface, therefore, lead to differences to the specified characteristic value. When designing the application, it is important to ensure that other components such as eccentric loads, lateral forces or torsional moments are prevented/minimized as far as possible, as these disturbance variables can lead to distortion 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 choice of force transducer design can differ. GTM offers force transducers with (1) bending ring principle (K series force transducer), (2) bending beams based to the symmetrical spoke principle (K series force transducer), (3) bending beams (KL series force transducer), (4) thrust spokes (DR series force transducer) or (5) longitudinal and transverse expansion in the tube (RF series force transducer). In addition to the nominal force, the design and the force transducer material used are the determining boundary conditions of a force sensor.

In some force measurements, it may be necessary to equip the force transducer with mechanical accessories. Using mechanical GTM adapters, GTM force transducers can be optimally integrated into the respective measurement task. Mechanical mounting aids such as base plates or thrust pieces form an inseparable systemic unit in order to achieve precise and reliable measurement results with GTM force sensors. That is why we offer a wide range of suitable mechanical accessories in accordance with ISO376 for a broad spectrum of demanding applications.

Measuring cables and the corresponding plugs and sockets are a particularly important part of the overall force measurement, as 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 right choice. You can find detailed information here.

• The strain gauge (SG) technology used for GTM force transducers is considered proven and cost-effective.
• GTM force transducers 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 assebmly in a wide range of applications and industries.
• GTM force transducers are ideally suited for static and dynamic force measurement applications.
• The special design of the GTM force transducers ensures high resistance to parasitic forces or moment influences.
• GTM force transducers feature very good temperature compensation thanks to intelligent interconnection of the strain gages and the supplementary elements to form a Wheatstone bridge circuit.
• Due to the use of high quality materials, GTM force transducers are characterized by high fatigue strength.GTM force transducers have outstanding long-term stability and therefore represent a valuable investment in your overall application.