Introduction
The front bulkhead (circled in red below) is one of two bulkheads present within the car. It provides structural integrity to the whole assembly and thus, must be tested to make sure that it reaches the standards we set for it to achieve.
We will be testing primarily for tensile, compressive, and shear strength for this panel in particular. Further explanation will be provided in the next section.
Tests to be used
We will attempt to use the figure above when determining which test we would like to use. This was acquired from the asc regulations and it outlines where the car must survive an impact. As you can see, there are many cases where it hits the front of the car. As you can imagine, trying to recreate a test that strikes the bulkhead at such an odd angle would be very difficult, if not impossible. This is why I have decided that we should just focus on the cases where it hits the car in a more simple manner such as directly from the top, directly in front, and directly beside it. We will probably want to test compressive, shear, and tensile properties so that is why I have chosen the three testing standards that we will emulate below.
Procedures for tests
Below, I have inserted the three tests we are planning on doing in the three sections below. With them, I have also given a link to the summarized version of each testing standard if you wish to acquire more information.
Note that I have not included the whole procedure of each test below, I have just included what I feel is needed for a general idea of what will be done.
ASTM C393 Standard Test Method for Shear Strength
Condition the specimen in a chamber if the test environment is not the same as a conditioned environment.
Measure the length, width and thickness at three places in the specimen.
Place the specimen into the test fixture as shown in the equipment and apparatus section.
Attach the deflection transducer (if we choose to use one).
Apply a compressive force to the specimen until failure or until a deflection equal to the thickness is reached.
Variable | Quantity |
|---|---|
Load rate | 6mm/min |
Failure occurence | 3-6 minutes |
Support bar separation | 150 mm |
ASTM D3039 Standard Test Methods for Tensile Properties
Measure the specimen in 3 places and report average thickness and width as well as average area.
Place the specimen into the grips of the testing machine
Apply the force until failure occurs
Variable | Quantity |
Failure occurence | 1 to 10 min |
Head displacement | 2mm/min |
ASTM D3410 Standard Test Method for Compressive Properties of Polymer Matric Composite Materials
Condition specimens
Apply strain gages/extensometers to both faces of the specimen(if we choose to).
Monitor test temperature using thermocouples (if we choose to).
If needed, move the testing machine crosshead to open the distance between the 2 housing blocks so both the upper and lower wedge rip assemblies may be accessed.
Close the upper grips manually to check the specimen's vertical displacement. Do it with the lower grips as well. The upper grips should be in full contact with the wedge when closed. Repeat if we need to.
Attach strain transducers if they will be used. Then, attach the strain recording instrumentation to the strain gages or other transducers on the specimen. Then, remove any remaining preload and zero the transducer(s).
Apply the force to the fixture at the specified rate until failure while recording data.
Variable | Quantity |
|---|---|
Strain Rate | 0.01 min-1 |
Crosshead Displacement | 1.5 mm/min |
Failure occurence | 1-10 min |