In all but a very few vehicles today crumple or crush zones are employed as a method to decrease energy transfer to occupants in a crash. For the most part crumple zones form a structural part of car such as frontal rail or rear bumper beams. In the early phases of development these crumple zones can be designed through a series of equations which take in account materials properties and geometrical features.
This assignment comprises the subsequent three sections:
problem1. Provide a literature review of thin-walled tube crushing and bending high-lighting mechanisms of deformation with respect to material and geometry including such phenomena of strain-rate sensitivity.
problem2. Using an envelope of 600 mm in length, and a maximum of 100mm width and 100mm depth; design a crumple zone that is capable of absorbing ~8,500 Joules of energy at 50 km/h. You can choose any geometrical shape and material to achieve this, but all choices have to be backed up by analytical equations. Use a crush distance of 75% of the original tube length (ie. 400 mm). Make sure if you use a strain-rate sensitive material you include this into your calculations.
problem3. Depending on your material choice do the following:
i. If you select a metallic material for a single lobe of deformation show how strain and stress profiles and ultimately fracture (if takes place) progress throughout the deformation, show this through explanations, computation and images
ii. If you select a composite material show how the fracture mechanisms/stress/strain work through lobe or ribbon formation; again show this by explanations, computation and images
- This should be done as your own personal piece of work, no group work allowed.
This assignment should be presented as a formal methodical report with clear unambiguous references. All computation and assumptions should be provided together with a complete explanation of all the terms employed. This assignment should be typed and in Microsoft Word *.docx format.