Abstract 4

This study aims to get close to the tension-tension portion of the Forming Limit Curve (FLC) of 38 um thick CP Gr2 Titanium with the use of the bulge test. With the miniaturization trend of technology, the forming abilities of Ti have to be evaluated because it is well known that the formability changes when moving from macro to micro scale. The hydraulic bulge test creates pure biaxial tension by clamping a flat foil sample to obtain a fixed boundary condition and then applying pressure on one side to promote material deformation. In order to ensure that pure biaxial tension has taken place, the strain history will be recorded by taking measurements of the strain at specific pressure intervals from the start up to the burst pressure. If the strain history has equal major and minor strains, pure biaxial tension is confirmed. Strain is measured by studying the deformation of a grid of 50 um in diameter circles that are on top of the thin foil. This thesis tests four different bulge diameters of 20 mm, 15 mm, 10 mm, and 2 mm. When bulge diameter decreases, size affects are expected to increase. Theoretical calculations will be compared to LS-Dyna simulations and experimental results to check whether the theory continues to apply when moving to the smaller diameter thin foil. The wide range of diameters tested from 20 mm to 2 mm will allow for clarification of any trends when undergoing miniaturization in forming.

Abstract 3

Title:

Hydraulic Bulge Testing of CP Gr2 Ti to Quantify Size Effects on the Forming Limit Curve when Undergoing Miniaturization

Abstract Draft 3:

This study aims to get close to the tension-tension portion of the Forming Limit Curve (FLC) of 38 um thick CP Gr2 Titanium with the use of the bulge test. The FLC helps to predict the forming behavior of sheet metal by showing safe and failure strain zones with minor and major strains as the axes. Various tests, including the tensile test, limited dome height test, cruciform test, and bulge test are used for obtaining data for different portions of the FLC. With the miniaturization trend of technology, the forming abilities of Ti have to be evaluated because it is well known that the formability changes when moving from macro to micro scale.

The hydraulic bulge test involves clamping a flat foil sample to obtain a fixed boundary condition and then applying pressure on one side to promote material deformation. If the boundary is circular and secure, pure biaxial tension takes place at the top of the bulge as the material deforms. Micro limited dome height tests already produce excellent FLCs, but the equibiaxial portion is difficult to obtain due to frictional effects. The bulge test is essentially friction free due to the use of hydraulic pressure, and its data can be used to complete the FLC for CP Gr2 Ti. In order to ensure that pure biaxial tension has taken place, the strain history will be recorded by taking measurements of the strain at specific pressure intervals from the start up to the burst pressure. If the strain history has equal major and minor strains, pure biaxial tension is confirmed.

Strain is measured by studying the deformation of a grid of 50 um in diameter circles that are on top of the thin foil. Since the Ti is 38 um thick, the strain at the top of the specimen is assumed to be approximately the same throughout the thickness. A scanning electron microscope takes pictures of the strain zone of interest. After pictures are taken, ImageJ software is used to fit ellipses to the deformed circles. The major and minor axes of the fitted ellipses are used to calculate the major and minor strains. 

This thesis tests four different bulge diameters of 20 mm, 15 mm, 10 mm, and 2 mm. When bulge diameter decreases, size affects are expected to increase. Theoretical equations for the bulge test exist, which include parameters such as pressure, thickness, dome height, diameter, radius of curvature, and material constants. Theoretical calculations will be compared to LS-Dyna simulations and experimental results to check whether the theory continues to apply when moving to the smaller diameter thin foil. The wide range of diameters tested from 20 mm to 2 mm will allow for clarification of any trends when undergoing miniaturization in forming. This study will compare theoretical, numerical, and experimental results in order to bridge the gap between the macro and micro scale.

Abstract 2

This was my first rough draft of the abstract. Bad.

Commercially Pure Grade 2 Titanium is commonly used in chemical, medical, and aerospace industries because of its high specific strength and excellent corrosion resistance. In order to limit the cost and weight in design, an accurate forming limit diagram (FLD) is desired to know the limits of the 38 micron thin foil's formability. In order to determine the equibiaxial tension portion of the FLD, experimental testing will take place with the hydraulic bulge test. In order to see any affects of bulge diameter, three different tool dies of 10 mm, 15 mm, and 20 mm will be utilized. The major and minor strains will be determined by first capturing images of the post-test grid with SEM and then using Fiji/ImagJ software. LS-DYNA software will also allow for a comparison between computational and experimental results. A linear 45 degree strain path is expected for each die diameter bulge test. A decrease in diameter is known to increase the burst pressure. The resulting forming limit diagram will help with efficient designs using Titanium thin foil. In the future, the affects of a combination of strain paths could be analyzed to determine potential new manufacturing methods.
I guess my idea of an abstract is different from what is needed for a thesis proposal abstract, which is ok. Now I will make another attempt. Some new aspects:
-Explain bulge test
-Add reasoning: testing to see if macro-scale equations still apply when going to smaller scale
-Clean up grammar, avoid using the same phrases multiple times


It is well known that the formability of metals change when moving from macro to micro scale. This study aims to get close to the tension-tension portion of the Forming Limit Curve (FLC) of 38 um thick CP Gr2 Titanium. The hydraulic bulge test involves clamping a sample to obtain a fixed boundary condition and then applying pressure on one side to promote material deformation. If the boundary is circular and secure, pure biaxial tension takes place at the top of the bulge as the material deforms. Micro limited dome height tests already produce excellent FLCs, but the equibiaxial portion is difficult to obtain due to frictional effects. The bulge test is essentially friction free due to the use of hydraulic pressure, and its data can be used to complete the FLC for CP Gr2 Ti. In order to ensure that pure biaxial tension has taken place, the strain history will be recorded by taking measurements of the strain at specific pressure intervals from the start up to the burst pressure. A grid of 50 um in diameter circles are placed on the foil and are measured post-deformation with the use of SEM and ImagJ. This thesis tests three different bulge diameters of 20 mm, 15 mm, and 10 mm. When bulge diameter decreases, size affects are expected to increase. Theoretical calculations of dome height will be compared to LS-Dyna simulations and experimental results to check whether the equations continue to apply when moving to the smaller diameter thin foil. This study will compare theoretical, numerical, and computational results in order to bridge the gap between the macro and micro scale.


I'll stop it there for today.

Title and Abstract

I have my committee together, and the next step is to propose my thesis. I need to have my ideas solidly together and be prepared for any questions.

So first: what will my title be?

Hydraulic Bulge Test of Commercially Pure Grade 2 Titanium for the Forming Limit Diagram on the Mesoscale

Hydraulic Bulge Test of CP Gr2 Titanium for Right Hand Side of the Forming Limit Diagram

Forming Limit Diagram of CP Gr2 Titanium with Hydraulic Bulge Test

Something like that? I should emphasize that I am focusing on the right hand side and particularly equibiaxial tension. Ok, I can work with that.


Abstract
-Intro: Why is this research important? (1-2 sentences)
Commercially Pure Grade 2 Titanium is commonly used in chemical, medical, and aerospace industries because of its high specific strength and excellent corrosion resistance. In order to limit the cost and weight in design, an accurate forming limit diagram (FLD) is desired to know the limits of the 38 micron thin foil's formability.

-Methodology (1-3 sentences): specific approach (theoretical, experimental, computational), measured variables and control parameters, (not step by step)
In order to determine the equibiaxial tension portion of the FLD, experimental testing will take place with the hydraulic bulge test. In order to see any affects of bulge diameter, three different tool dies of 10 mm, 15 mm, and 20 mm will be utilized. The major and minor strains will be determined by first capturing images of the post-test grid with SEM and then using Fiji/ImagJ software. LS-DYNA software will also allow for a comparison between computational and experimental results.

-Results (3-8 sentences): In my case, expected results. Specifics
A linear 45 degree strain path is expected for each die diameter bulge test. A decrease in diameter increases the burst pressure.

-Conclusion (1-2 sentences): significance of results, future steps
The resulting forming limit diagram will help with efficient designs using Titanium thin foil. In the future the affects of a combination of strain paths could be analyzed to determine potential new manufacturing methods.

And now, all together:
Commercially Pure Grade 2 Titanium is commonly used in chemical, medical, and aerospace industries because of its high specific strength and excellent corrosion resistance. In order to limit the cost and weight in design, an accurate forming limit diagram (FLD) is desired to know the limits of the 38 micron thin foil's formability. In order to determine the equibiaxial tension portion of the FLD, experimental testing will take place with the hydraulic bulge test. In order to see any affects of bulge diameter, three different tool dies of 10 mm, 15 mm, and 20 mm will be utilized. The major and minor strains will be determined by first capturing images of the post-test grid with SEM and then using Fiji/ImagJ software. LS-DYNA software will also allow for a comparison between computational and experimental results. A linear 45 degree strain path is expected for each die diameter bulge test. A decrease in diameter is known to increase the burst pressure. The resulting forming limit diagram will help with efficient designs using Titanium thin foil. In the future, the affects of a combination of strain paths could be analyzed to determine potential new manufacturing methods.


After meeting with my advisor, the above abstract is too "short." I need to make it sound more technical. Ehh, why? I like making my writing easy to understand. But oh well.

So I'm working on organizing myself. I have various projects and duties to attend to. I want to produce a good, actually beneficial thesis, and I can do it - through the use of organization. Perhaps updating this blog more can help. I have taken my final for my class already, and all I have left in front of me is a design project for an interview, a lot of grading, and this thesis.