Void and Density Analysis of Cyanate Ester Composites

In large scale composite manufacturing, voids and their frequency within prepreg materials play an important role in predicting the mechanical properties of a final composite laminate. The industry standard process for determining voids in composite materials is through resin digestion and resin ignition via ASTM D3171. One limitation to this standard is its ability to frequently produce negative void volume values in quality control testing, due to the
calculation sensitivity of input resin and fiber densities. For this reason, Toray Advanced Composites wanted to investigate the process steps of ASTM D3171 to determine if discrepancies in resin density data may be leading to negative void volumes in their EX-1515 cyanate ester resin system. In order to analyze the matrix density, three groups of materials were investigated including: neat EX-1515 resin, EX-1515/CN-60 composite, and EX-1515/Astroquartz composite. All three materials underwent dimensional and specific gravity density measurements, in addition to optical microscopy. In combination with data from resin ignition and digestion, the density data revealed that original assumed density for EX-1515 was lower than the actual density of the resin system, which led to the prevalence of negative void volume calculations. Furthermore, the results of the project revealed the importance of there being a range of density values for composite resin systems due to the high sensitivity of the process steps and calculations found within ASTM D3171.

Solvent Analysis of Phenolic Resin Glass Fiber Reinforced Prepreg

An investigation into whether high temperature or time has a stronger effect on the loss of volatiles present in phenolic resin glass fiber reinforced prepreg from B-stage till application manufacturing. The loss of volatiles resulted in a loss of tackiness which often rendered the prepreg unfit for application manufacturing.

Composite LiftWalker for Shurouq

          The picture above shows our final prototype, successfully lifting our team member Daniel Martinez.

The goal of this senior project was to design and build a new version of our project sponsor Charlie Gutierrez’s LiftWalker for Shurouq, our client.

Shurouq is a young woman who lives with her family in Egypt. She was born with multiple health conditions which resulted in leg contractures that have since left her unable to walk.

Charlie’s device, the New LiftWalker, has helped dozens of people with disabilities similar to Shurouq’s. However, Charlie’s standard design is made of stainless steel weighing up to 80 lb, which is both difficult and expensive to send to Egypt. For this reason, Charlie turned to the Mechanical Engineering Department at Cal Poly, challenging us to redesign his LiftWalker out of lightweight composite materials.