In all but a very few vehicles today crush or crumple zones are employed as a method to reduce energy transfer to the occupants in a crash.  For the most part crumple zones form a structural part of the car such as frontal rail or rear bumper beams.  In the early stages of development these crumple zones can be designed via a series of equations that take into account materials properties and geometrical features.

This assignment consists of the following three sections:

1. 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.

2. 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.

3. Depending on your material choice do the following:

a.  If you choose a metallic material for a single lobe of deformation show how stress and strain profiles and ultimately fracture (if occurs) progress through the deformation, show this via explanations, calculations and images

b.  If you choose a composite material show how the fracture mechanisms/stress/strain work through lobe or ribbon formation; again show this via explanations, calculations and images

This must be done as your own personal piece of work, no group work allowed.

This assignment must be presented as a formal methodical report with clear unambiguous references.  All calculations and assumptions must be provided together with a full explanation of all the terms used.  This assignment must be typed and in Microsoft Word *.docx format and submitted via DSO.  No hand written or hand submitted assignments will be accepted.

Extensions will only be granted if asked for in writing (email) three days before the due date; a maximum of 7 days will be granted if circumstances are valid - having other assignment due is not a valid reason.  Students can only ask for one extension for the trimester period - thus if you have an extension for assignment one you are not able to have another extension for assignment 2 unless under very exceptional circumstances.  If your assignment is greater than three days late you will receive zero for that assessment task.