Influence of geometry and placement configuration on side forces in compression springs

2019-11-12T20:17:58Z (GMT) by Rahul Deshmukh
A leading cause of premature failure and excessive wear and tear in mechanical components that rely on compression springs for their operation is the development of unwanted side forces when the spring is compressed.
These side forces are usually around 10% - 20% of the magnitude of the axial load and point in different directions in the plane perpendicular to the axis of the spring.
The magnitude and direction of the resultant of side forces varies very non-linearly and unpredictably even though the axial force behavior of the spring is very consistent and predictable.
Since these side forces have to be resisted by the housing components that hold the spring in place, it is difficult to design these components for optimal operation.

The hypothesis of this study is that side forces are highly sensitive to small changes in spring geometry and its placement configuration in the housing.
Several experiments are conducted to measure the axial and side forces in barrel springs and two different types of finite element models are developed and calibrated to model the spring behavior.
Spring geometry and placement are parameterized using several control variables and an approach based on design of experiments is used to identify the critical parameters that control the behavior of side-forces.
The models resulted in deeper insight into the development of side forces as the spring is progressively loaded and how its contact interactions with the housing lead to changes in the side force.
It was found that side-forces are indeed sensitive to variations in spring geometry and placement.
These sensitivities are quantified to enable designers to and manufacturers of such springs to gain more control of side force variations between different spring specimens.