Torsional Stiffness Study

Problem: The feet of a prototype desk design are deflecting an unacceptable amount under load.  The offset casters cause a moment about the length of the foot. The system is non-linear, meaning as the feet deflect, the moment arm increase and the torque on the foot increases, even though the load is constant.

desk

iso

Solution: Determine the required increase in torsional stiffness of the foot for an acceptable deflection under load.  In this case, the acceptable deflection would be 1/6 the deflection of the original prototype.  Fortunately, due to the non-linear nature of the system, a torsional stiffness increase of only 3X was found to be required to achieve the desired deflection, not the 6X required if the system was linear.

The next step was to evaluate the torsional stiffness of modified foot designs, done with a finite element analysis program, to determine the effectiveness of the modified designs.  The figures below show simplified versions of the baseline (original prototype) foot, and one of the modified designs.


Baseline Foot

Modified Foot