Evaluation of Ground Anchor for Temporary Shelters : - Performance, Design and Alternative Materials

Sammanfattning: Better Shelter is a company, developing and providing module housing units for refugees in crisis areas. These module housing units are kept in place against wind and harsh conditions by 10 ground anchors, that are buried and tied to the frame. This bachelor thesis study and evaluate the mechanical behavior of these anchors, investigate the possibility to replace the current material from an aluminum alloy to a glass fibre-reinforced plastic and present a new and improved design. Evaluation of the ground anchor wire is not relevant in this report. The results are based on four simulations executed in the FEM program, ANSYS Workbench, including provided and custom made CAD models of the anchor for both materials. From relevant loading cases, static and alternating, with an amplitude force of 2000 N , relevant information was collected and analyzed. Relevant data in this case include equivalent and maximum principal stress as well as the safety factor and cyclic fatigue life. The simulations showed that minor plasticity and damage will occur to the current anchor in both materials. This is debatable since the computer simulation is based on models that are often an unreal representation of reality. As an example in this case, the stress levels in sharp corners of the CAD model highly exceeds the levels that would be considered realistic. However, great improvements could be observed with the new anchor design in both materials regarding strength and reduced volume. This concludes that a change of design and material is motivated mechanically and economically. Improvements include lowering cost to 4.44 SEK per unit which is a reduction by 54.8% as well as reducing the weight from 29 g to 11.8 g per unit.