Introduction
Contributors:
Erika Rugh –
Undergraduate senior at Sweet Briar College majoring in engineering
Collin Malek
– Undergraduate senior at Oakland University majoring in mechanical engineering
Project
Description:
This project
aims to better implement high and ultra-high strength steels in the automotive
industry which allows for an improved fuel economy. Specifically, this program addresses the
problem of splitting from the sheared edge that occurs when tension is applied
along the sheared surface. Presented by
Dr. Golovashchenko, the following are the goals of this assignment.
- Study sheared surface parameters (burr
height, burnished area - indentation of the tool before initiation of fracture,
height of the brittle zone and rollover zone) for the range of cutting clearances
by: a) observing the sheared surface under the microscope and b) preparing
crosssections for several steels employed in automotive industry, such as
Interstitial Free steel, Bake Hardenable steel, High Strength Low Alloy Steel
and Dual Phase Steel DP980.
- Understand the effects of tool wear
during trimming process on sheared edge parameters by: a) comparing the
burnished areas of trimmed samples selected after specified number of cuts and
b) performing stretchability experiments of these selected samples.
- Analyze the mechanism of fracture of
sheared samples as a function of cutting clearance and cutting edge condition
and locate initiation of fracture during stretching of sheared edge of sheet
metal samples.
- Compare sheared edge stretchability
for sheared surfaces fabricated by piercing 10mm in diameter holes and trimmed
along the straight line by measuring the strains along the perimeter of
stretched sheared edge.
We have been working on testing the stretchability of our DP980 specimens. To do this we have to prepare the samples by:
This week we went to an SAE vehicle event for the 2017 Chrysler Pacifica. Speakers spoke about the design and architecture of the minivan as well as how it compares to competitors' models and previous designs. We had the chance to see a few of these vehicles and test out some of the new features. The event also featured many of the suppliers that contributed to the production of the Pacifica. We really enjoyed attending this vehicle showcase and the closer look at the engineering behind this new product. 
The image on the left shows us taking pictures using a microscope to measure the burnished area and burr depth of a specimen. We used a program called SPOT to capture an image from the microscope and draw 20 vertical lines which are measured in pixels. The first 10 lines (green) are from the top edge to the bottom of the burnished area, and the next 10 lines (red) are from the top edge to the bottom edge. We have been using this method during our first week to take measurements of the sheared edge of steel samples cut by a specific tool. These samples are organized by how many cuts a machine has made up to that point. The samples that we were testing were taken every 50,000 cuts made by the machine with the initial batch taken from zero cuts. Figuring out how to obtain the highest quality image took some patience since the glare from the burnished area would distort the image, but after some time we got the hang of it. 