# Design of Truck Shell

Armadillo Designs has tasked us with helping them create a watertight truck shell which has a convertible roof. Helping provide construction workers, and other trades alike, with a secure storage option for the bed of their truck.

### Sam Hunt

Project Manager

Sam Hunt is a Manufacturing Engineer from Santa Rosa, CA. His main roles were CAD Modeling potential solutions, design analysis, manufacturing, and testing. Sam reported data directly to the team to analyze, and documented testing results through caliper measurements, pictures, and video recordings. This was crucial for finalizing and concluding the recommendation report.

### Austin Warren

Production Organizer

Austin Warren is a fourth year Industrial Engineering major from Berkeley, CA. His main roles were design analysis, testing, researching material properties, prototyping, brainstorming potential solutions. This was all beneficial for the finalization and overall product as a whole.

### Acknowledgements

We would like to thank our sponsor Fabian Araujo for allowing us to work on this project, and guiding us through the current state. We would also like to thank Jill Speece for guiding our team on a weekly basis to the final report, and Trian Georgeou of the IME Department for his industry insights and material recommendations.

## Test Summary

To evaluate the different designs and materials for our project, we used priority matrix diagrams to come up with the highest benefit and easiest to implement solutions. We initially researched HDPE sliding roof panel designs with four HDPE panels sliding along G-channels. To test the HDPE, we subjected it to a water test and then direct sunlight for a week. After this time, there was considerable warpage and distortion in the panels. We tried to nullify the warpage and decrease weight by routing grooves into the HDPE, but this only created bowing in the opposite direction. The team then tested fiberglass for the roof material, as well as a series of G-channels each designated for one of the panels. After creating the prototype, this design allowed the panels to slide very well – being able to be opened or closed within 5 seconds. However, there was still visible warpage in the middle of the fiberglass panels.

## Roof Materials

Due to its vibration resistance, machinability, and low coefficient of static friction, High Density Polyethylene (HDPE) was considered as a roofing material. HDPE Stress/Strain Graph received from  (Amjadi & Fatemi, 2020)

Due to being industry standard for truck shells, and having a high strength to weight ratio, Fiberglass Reinforced Plastic (FRP) was considered as a roofing material. Graph received from (Haery et al., 2012).

## Material Analysis

Stress/strain analyses were key in understanding the elastic modulus and ultimate tensile strength of each material. Elastic modulus measures how stiff a material is and ultimate tensile strength measures how much stress a material can withstand before it fails. HDPE was a top contender amongst other materials as it is very cost-effective. A 4mm thick sample had an ultimate tensile strength of about 20 MPa and an elastic modulus of about 800 MPa. HDPE is also a very slick material and will provide less sliding friction in the retractable roof mechanism. Fiberglass material is the industry standard in truck shells because it is lightweight and durable. It has excellent material properties, a 5 mm sample demonstrated an ultimate tensile strength of about 100 MPa. The downside of fiberglass is it is more expensive and brittle. If a failure event were to happen, fiberglass would break into pieces instead of deforming.

## Verification & Validation

The shell was subjected to water-tightness tests, shock and vibration tests, construction site testing, as well as others.

Video cameras were used to document the testing, and allow the team to analyze and observe results more closely post-testing

Specifications
Weight ~200 lbs

## Works Cited

### Amjadi, M., & Fatemi, A. (2020). Tensile Behavior of High-Density Polyethylene Including the Effects of Processing Technique, Thickness, Temperature, and Strain Rate. Polymers, 12(9), 1857. https://doi.org/10.3390/polym12091857

Haery, H., Zahari, R., Kuntjoro, W., & Taib, Y. (2012). Tensile strength of notched woven fabric hybrid glass, carbon/epoxy composite laminates. Journal Of Industrial Textiles, 43(3), 383-395. https://doi.org/10.1177/1528083712456055

## Our Project Slides

Sun Exposure Test
Panel Routing
Routing Warpage
Completed Shell
Construction Site Test
Completed Shell