Question

Among the following, torque is measured with

• A. Cantilever-type bender bimorph
• B. Parallel bimorph
• C. Series bimorph
• D. Piezoelectric strain multi morph

Hint:

To measure torque or force using a piezoelectric bimorph crystal, the sensor is typically mounted as a cantilever-type bender. This setup converts mechanical twisting or bending deflection into an electrical charge.

Answer 1

The Correct Option is A

Concept: A piezoelectric bimorph is a flexible transducer element constructed by bonding together two separate, thin sheets of piezoelectric ceramic (such as PZT). These sheets are oriented so that an applied mechanical force causes one layer to expand while the other contracts. This push-pull deformation produces a measurable electrical charge via the piezoelectric effect.

Step 1: Understanding torque transduction mechanisms.
Torque is a rotational force acting through a lever arm ($T = F \times r$). To measure torque using a piezoelectric element, the rotational twisting motion must be converted into a localized bending stress:
• In a cantilever-type bender bimorph configuration, one end of the bimorph assembly is securely clamped to a rigid frame, while the opposing free end is coupled to a small lever arm attached to the rotating shaft.
• When torque is applied to the shaft, the lever arm deflects the free end of the cantilever beam. This creates a bending moment along the bimorph structure, generating an electrical output proportional to the applied torque.

Step 2: Distinguishing alternative bimorph structures.
Standard parallel and series bimorphs refer to the internal electrical wiring configurations used to optimize either voltage sensitivity or charge output. However, to convert torque into linear bending stress, the device must be housed in a mechanical cantilever-type bender mounting assembly, validating Option (A).