Super Power or Buckling?

I am sure this has happened to everyone, you are working with a tool and suddenly the tool bends. You wonder if you have suddenly gained super-powers as they show in the movies. I wish it were true, but most likely the component buckled. 

Buckling refers to sudden large displacements due to axial loads. Slender
structures subject to axial loads can fail due to buckling at load levels lower
than those required to cause material failure. Buckling can occur in different
modes under the effect of different load levels. In many cases, only the lowest
buckling load is of interest.

My friend recently experienced buckling on his plant water sprayer handle. He too claimed he had the power to move the world. I fired up SolidWorks Simulation to check if we got some insights into the design. 

 

 



First we ran a static test to check how the part faired. It is here we realized the load was not sufficient to cause yield. Then the thought came to check for buckling. SolidWorks Simulation calculates Buckling load factor or buckling factor of safety. The buckling factor of safety (BFS) is the factor of safety against buckling or
the ratio of the buckling loads to the applied loads. 

The set up for buckling and static test remain the same. After running a buckling study you can plot displacements. These displacements or mode shapes ilustrate the profile i.e displacement of nodes relative to one another. We can typically ignore these displacement values. What we are interested in is the critical load factor displayed on the upper left hand corner. 

A model can buckle in different shapes under different levels of loading. The shape model takes while buckling is the buckling mode shape. When buckling is critical design factor, calculating multiple buckling modes helps in locating the weak areas of the model. If Buckling load factor is between 0 and 1; The applied loads exceed the estimated critical loads. Buckling is expected. In this case Buckling load factor of 0.98 shows buckling would occur at the red spot.

New sprayer-handle design

The replacement bottle sprayer-head looked nothing similar to the old one. Well I guess someone figured this out and made design-changes accordingly. 

Super Powers not so nuch.... Simulation is the way to go.

Rajat Trehan

Product Manager : Simulation 

Computer Aided Technology Inc.