If two elephants were suspended at the same time by a thin composite strip one-tenth of an inch thick and one inch wide, what are the chances they would break the strip and fall? According to Advaero Technologies in North Carolina, zero (unless you have two African Savanna elephants, which weight up to 16,500 pounds each.) A new 150 gsm bi-angle non- crimp carbon fiber produced by Chomarat and cured using Advaero’s Heated Vacuum Assisted Resin Trans- fer Molding (HVARTM) technology will be able to withstand the weight of 24,000 pounds — the equivalent of two average elephants — before breaking. Not only would this technology make composites competitive against metals, it could be an entry card for applications in new markets.
Dr. Ajit Kelkar, professor and chair of the Nanoengineering Department at the Joint School of Nanoscience and Nanoengineering at the North Caro- lina A&T State University (NC A&T), and co-founder of Advaero Technolo- gies, is excited for the HVARTM composite manufacturing breakthrough and what this new technology means for the industry.
Last year, Advaero Technologies, a spin-off company based on research from NC A&T State University, began working with a global consortium including Stanford University and Chomarat Textile Industries to de- velop the next generation aircraft using cheaper out-of-autoclave tech- nology. “We decided to start our research with regular vacuum assisted resin transfer molding (VARTM), to build similar parts using a new fabric designed by a member of our consor- tium at Stanford,” says Kelkar.
Dr. Kelkar has an extensive 30 year career in aerospace composites. He knows the difficulty in curing aerospace quality parts at room tem- perature is that resins don’t reach the correct viscosity to flow to all the sections in the mold like it would in an autoclave. Thus, the team decided to wrap the mold in heat blankets to increase the temperature of the resin to be distributed throughout the part. After weeks of trial and error they finally developed a helicopter piece that was just as strong as the auto- clave manufactured part.
Benefits beyond autoclave
The group found the benefits of HVARTM were tremendous com- pared to other comparable processes. It resulted in better resin viscosity, a 65 percent fiber volume fraction, which is similar to autoclave cured parts, part strength equal to auto- clave, and a cheaper and mobile manufacturing process with the abil- ity to create recycled carbon fiber parts. Advaero is currently designing replacement carbon fiber parts for the Boeing CH-46 helicopter to help reduce weight and the price of current aluminum parts.