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# 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...

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
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SEM422 – Advanced Stress Analysis Assignment 1 thTrimester 2 2013 – Due date 19 August @ 11.59pm 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...

## Solution

David answered on Dec 29 2021
SEM422 – Advanced Stress Analysis Assignment 1
Literature review
Crumple zones were introduced by Mercedes Benz for the first time in 1959. Crumple zones
helps in abso
ing the energy produced during collision. It works on the principle of Newton’s
First Law. Working of crumple zone is very simple and based on basic laws of physics. It is
made up of deformable soft materials fixed at the front, side and rear of the vehicle. A thin
walled tube made up of steel can be used for making crumple zones. It is commonly visible on
the front and rear of the vehicle.
Crumple Locations in Cars (secret, 2013)
During a collision crumple zone helps in abso
ing the energy generated during collapse and
some part of that energy is utilized by the crumple material during deformation and crushing.
Energy abso
ed completely depends on the material and energy generated depends on the speed
of the vehicle.
Energy lost can be calculated using newton’s second law of motion which states that rate of
change of momentum is equal to the force applied.
Force = Rate of change of momentum = dp/dt
Hence by calculating the crushing distance we will be able to calculate energy abso
ed by the
crumple. ...
SOLUTION.PDF