**Strength analysis of pneumatic clamps - linear buckling analysis**

*Strength analysis of pneumatic clamps - linear buckling analysis*

*Solution:*

- Obtain a 3D CAD model
- Simplify model to save time and costs
- Load validation
- Proposed new design

The pneumatic clamps have to be analyzed in three separate studies.

The first study is a linear static analysis. Aim of the linear static analysis is to identify stresses which should not exceed allowable values of each component. It is the yield strength of a material in this case.

The second study is a linear buckling analysis. This analysis validates that clamps are rigid enough, that buckling does not occur under the maximal force exerted by a pneumatic cylinder.

The third study is a non-linear static analysis. As clamps are designed to plastically deform metal pin, analysis is performed to verify, that no plastic deformation occurs on clamps working surfaces.

This post describes the procedure of the second study – linear buckling analysis.

The clamps CAD model is shown in Figure 1 and supplied by a customer. The peripherals are removed as they have no impact on results. The pneumatic cylinder is also removed and it is replaced by the force acting to the clamp arms. As the model is symmetric it is convenient to only consider half of the model to save costs and time. Figure 2 shows the half-symmetry model suitable for analysis.

Fig. 3 – Meshed half-symmetry CAD model

Fig. 4 – Mesh element type, HEX8, HEX20, TETRA4, TETRA10

Boundary conditions are shown in Figure 5: Lower flange of basement profile is fixed in all 6 degrees of freedom (C). The symmetry plane is constrained by frictionless support (A). The clamp working face is also constrained by frictionless support (B). The maximum force (produced by the operating pressure of the pneumatic valve) acts to the lower part of the arm shown in Figure 6. The surfaces between components are in No Separation contact.

Conclusion: Analysis has shown that buckling behaviour does not occur. The buckling occurs at load which have to 15 times greater than actual load. The first study deals with the plasticity of components. It is clear that plasticity would occur much earlier than buckling behaviour. Therefore the buckling behaviour is not managing.