Static & Dynamic FEA Analysis – Skate Ramp Modifications

We performed static and dynamic finite element analysis on various design modifications of skateboard ramps after a client/ manufacturer found permanent deformations on one of its ramps.

The finite element method is a numerical technique that is used to predict the behavior of complex structures. Finite element methods were originally developed and used by large corporations and research companies during the mid-1960s. Although finite element analysis programs became commercially available in the early 1970’s, they did not become a commonly used design tool until the personal computer became commonplace in the 1980’s.

In general, the accuracy of finite element results is dependent on how well the finite element model and its applied loading represent the actual part and loading conditions. Simplifications in geometry and how the mechanical interaction between connecting parts (such as bolted joints and weldments) represented in a finite element model can have a significant effect on the results.

All metal in the ramp structure is galvanized steel, and the edging on the wedge and box are HRPO (hot-rolled pickled and oiled) steel. The full FEA model (box structure & wedge) comprises 8265 elements and 23856 nodes. The wedge is approximately 112 inches long, 48 inches tall and 48 inches wide, while the box is approximately 48 inches in length, height and width.

In modeling the wedge and box, shell elements (SHELL93) were used, with thickness specified in for the elements. Layered structural shell elements (SHELL99) were used to model the wedge and box riding surfaces. This accounts for the three adjacent layers of material.

Skate ramp products are subjected to a variety of loads, primarily from users on roller blades, skateboards, and bicycles. The maximum loading condition was determined to be the result of a heavy bicyclist landing on the ramp initially on one wheel. A total weight of 250 lb was used to account for the bicycle and rider. A dynamic load factor was calculated to account for the impact of the rider on the ramp or box surface. This condition caused an overstress – and design modifications were recommended.

We Perform Dynamic Analysis on Structures for Clients in Various Industries. To Learn More, see Finite Element Analysis.