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Torsion spring with variable stiffness

Alternative for springs with constant stiffness

Mechanical springs are used in almost all mechanisms. They can be used to reduce shocks, apply a force, store energy or change natural frequencies. The major drawback is that the spring stiffness is constant, and thus is chosen during design and optimized for one working condition. Active controllable springs exist, but these devices consume continuously power, which is the reason why they are usually avoided to lower operating costs.

MECH_ torsion spring


This design realizes a torsion spring, of which the stiffness is changeable during normal operation. Since only standard components are used, the cost of implementation of this new technology into existing applications is low. It has a limited number of design parameters, which simplifies the implementation, although gives enough freedom to tune the characteristics for each specific application. The device is scalable and the power source used to vary the stiffness may be electrical, pneumatic or hydraulic. During normal operation as a torsion spring no power is required, only when the stiffness is varied. This can be done at every moment in time during normal operation. A demo setup is built to show the working principle.

Patent details

A patent application for this design has been filed in Europe, US and Canada.

Competitive advantages

This design has a number of advantages, depending on the application.

  • By optimizing the stiffness repetitive processes become more energy efficient.
  • Devices that interact with humans are more personalized, since each person can choose ideal softness. This implies more costumers will be satisfied with fewer different products.
  • Lower design cost since stiffness does not have to be defined in an early design stage, but adjustments are even possible by stores or retailers.

Collaboration details

Vrije Universiteit Brussel is interested in entering into license agreements, partnerships and joint R&D projects to implement this design into your applications (automotive, agricultural machines, prosthetic devices,...).


Hugo Loosvelt
IP & Licensing Manager

Mechanical Engineering (MECH)
Dirk Lefeber
[T] +32 2 629 28 64

Business development:
Lennert Vierendeels
[T] +32 2 629 28 08
[M] +32 472 71 29 69