Week Four

We received one of the three bones printed from the .stl file that we converted last week. We measured the length, and the cross section length of the different parts of the bone (including cross sections at the hip, lower hip, flattened, mid-shaft  lower mid-shaft, above the knee, and the lump).

We then applied the Three Point Bending test to the bone, and figured out the distance between 2 loads to be 0.226 in (8.5 mm)

Since the length of our bone is too small (14.6 mm) comparing to the width of the force applicator, our result might not be accurate. We were advised to scale the dimensions of the bone to 100 mm for the subsequent bones.

Index finger comparison showing the printed model

The printed model on the Three Point Flexural Machine showing that the width of the force applicator is larger than the length of the printed model

The .stl file of our bone is saved as facet feature in Creo; it is not a solid that has definite volume and shape. We are trying to convert the facet feature to a real solid so that we can adjust and modify the geometry of the bones.

Unfortunately, it appears that using a facet feature will prove impossible for the nature of this project. We have tried multiple programs to edit and/or convert the file into a form that can be edited more easily within Creo. Since we have to be able to edit the geometry of the bone, the group is trying a brute force approach to modeling the bone within Creo by creating a series of sketches that match the axial geometry of the bone and then using the swept blend tool to create a 3D model of the bone from the sketches. While this method is extremely labor intensive, we are very confident that it will create a successful, accurate model of the bone.

Week Three

We received our printed plastic model of a simple mouse femur.

We got the CT Scan of the mouse femur, and used ImageJ to view the it in 2D. We then imported the extracted file to ITK Snap in order to see the femur in 3D and tried to convert the file type to .stl so that we could import it to Creo.

By the end of class we were able to get a model together, but we had difficulties in sending it to the printer.  Our first files were too large to send, and then when we tried compressing the files, they came out corrupted and weren't able to print.

The initial CAD model we created

After much struggling with trying to simplify the model to decrease the file size, we had a breakthrough over the weekend when an additional feature of InVesalius was discovered that allowed the removal of extraneous parts.  Not only did this reduce the file size by almost half, but it also enabled us to eliminate things such as the knee cap which showed up in the CT scan, but are not studied in this project.  A walk-through will be posted sometime this week.
Unfortunately, we still have few ideas for how we might be able to edit the model, but that task will be tackled when it comes time.

The second healthy bone model we created.  This one lacks the extraneous portions, and the surface of the bone is smoother, simplifying the file and reducing the amount of waste that would be created during printing.

Week Two

We started lab section htis week with an overview of the math behind this project.  As a class, we derived the equations to relate stress, strain, modulus of the material, force applied, moment of inertia, and length.  We then created a simple Matlab script to plot displacement versus the estimated forces using inputted properties of the flexural test.  We took a trip up to the sixth floor of Bossone to see the Three Point Flexural Test machine, so that we could know the minimum length that can fit on the machine.  We rounded this out by creating a simple CREO model to test on the machine next week.



Our simple  model

Week One

           This week marked the start of our Engineering 103 Freshman Design Project. After getting some background information on what exactly we would be doing, we began by creating an outline for our design proposal. The most involved portion of today was setting up our blog. Below is the template we formatted for our design proposal:

INTRODUCTION:

• Describe genetic mutations & properties/mechanisms of a bone
• Explain how mutations affect bones
• Objective = design bone out of weaker plastic that is still as strong/stiff as a healthy bone.
• Tasks= create 3 bones, test bone strengths, use CREO
• Challenges= figure out how to convert image files, how to apply math equations, and improve bone design and geometry.
• Outcomes= a successful bone design made out of weakened plastic.

DELIVERABLES:

• 3 bones:
• one healthy, one mutated, and the design.

• CREO drawings
• stiffness/force equations
• lab results and analysis of each modified bone design.

TECHNICAL ACTIVITIES:

3.1= Healthy Bone

3.1.1= CAD Model

3.1.2= Printing/Mechanism

3.2= Mutated Bone

3.2.1= CAD Model

3.2.2= Printing Mechanism

3.3= Designed Bone

3.3.1= CAD Model

3.3.2= Printing Mechanism

TIMELINE:

      Week

TASK	1	2	3	4	5	6	7	8	9	10
Set up blog	x	x
CAD design		x	x
Testing		x	x
Analyzing Data				x
Redesign					x
Testing						x	x
Analyze							x	x
Redesign								x
Final Proposal									x	x

FACILITIES:

• Labs
• CREO
• Literature related to bones/mutations
• 3D Printer
• 3-Pt Bending Machine
• CT Scan of bone

EXPERTISE:

• CREO
• Blogging
• Ability to apply math
• Knowledge of bones
• Image J (skills on converting files)