SBIR-STTR Award

Carbon fiber-reinforced polymer (CFRP) composites offers the greatest potential for weight reduction in automotive vehicles, resulting in improved fuel efficiency and lowered CO2 emission. However, a major obstacle to broad commercial deployment is the high- cost and insufficient inspection of invisible damage. CFRP composites are susceptible to impact damage, resulting in significant loss of strength and stiffness without sign of damage on the surface. Unknown aging effects of CFRP composites also cause reliability concerns. Therefore, frequent inspection is required by trained personnel using expensive nondestructive testing equipment. To address this obstacle, this project develops a groundbreaking self-sensing self-sustaining CFRP (S4CFRP) composites system that can detect and warn users of any damage at the moment when it occurs. The system is entirely powered by energy self-harvested from vehicle vibration. The key innovation of the S4CFRP composites is in the transformation of structural materials, i.e., the carbon fiber and polymer, into an integrated sensor and energy harvester, without requiring any additional materials or devices to be inserted. In other words, the S4CFRPTM composites are a new lightweight multifunctional structural material integrated with self-sustaining self-sensing intelligence that enhances the structural safety and reliability with virtually no added cost or weight. The S4CFRPTM composites are a novel concept which has never been studied for integrated self-sensing and energy harvesting. The Phase I objective is to design and create S4CFRPTM composites specimens and experimentally demonstrate their feasibility of continuous monitoring and real-time damage detection, using the energy self-harvested from vehicle vibration. The S4CFRP composites specimens will be fabricated along with low-power circuits with embedded software. They will be experimentally evaluated in terms of sensitivity to damage and efficiency of energy harvesting. Major technical challenges are anticipated such as how to distinguish damage signals from vehicle vibration signals. Leveraging their significant experience in related R&D areas, the project team has laid out novel approaches to tackle these challenges and demonstrate the technology feasibility by the end of Phase I. The goal is to make the S4CFRP composites ready for commercialization by the end of SBIR Phase II, in which the project team will collaborate with automakers and suppliers to develop a prototype vehicle structural component and conduct large- scale tests. Because of the multiple important functionalities created in the lightweight CFRP composites without increasing cost or weight, S4CFRP composites are expected to be adopted by the automotive industry. By addressing the safety and reliability obstacle, S4CFRP will help accelerate the commercialization of lightweight CFRP vehicles. The resulting vehicle weight reduction will improve fuel efficiency and reduce CO2 emission. Lighter vehicle weight will also alleviate stress on roads and bridges, resulting in savings in maintenance cost of aging transportation infrastructure. Furthermore, the S4CFRP composites will enable novel applications in aviation, wind energy, medical and many other industries, making a long lasting impact to the quality of life and economic prosperity while preserving the environment.

Driven by zero carbon emission goals, lightweight highstrength carbon fiberreinforced polymer CFRP composites have emerged as the nextgeneration structural materials for automotive vehicles. However, their widespread adoption by the automotive industry is hindered by two significant obstacles: the high cost of carbon fibers and reliability concerns coupled with difficult damage inspection. CFRP composites are susceptible to impact damage and growth of damage leads to sudden loss in structural integrity. Such damage often cannot be seen by the naked eye, and thus frequent inspection is required using expensive nondestructive testing equipment. This SBIR project addresses both of these obstacles by developing a gamechanging, lowcost Sustainable Lightweight Intelligent Composite SLIC, a natural fiberhybridized CFRP with self powered insitu selfhealth monitoring functionalities and improved crashworthiness critical for vehicle applications. The Phase I effort successfully demonstrated the feasibility of transforming structural materials into a piezoelectric sensor and a vibration energy harvester without requiring devices to be inserted. To realize this innovative idea, a novel circuit was developed that, for the first time, enabled simultaneous sensing and energy harvesting. This selfpowered selfsensing functionality was experimentally validated in Phase I. Building on this success, the proposed Phase II effort will further expand the SLIC functionalities to tackle both of the CFRP cost and reliability inspection obstacles. An additional novel complementary piezoresistive sensor will be created to not only enhance the reliability of insitu damage detection, but also to enable determination of damage location. Incorporation of natural fibers will not only reduce cost, but also improve crashworthinessthe most critical requirement for automotive vehicle structural materials. Multifunctional SLIC specimens including sensing and energy harvesting circuitry hardware and software will be created and evaluated through tensile, bending, impact loading and damaging tests. Finally, a scaled SLIC bumper beam will be molded to demonstrate the viability of SLIC in a major vehicle safety component. By delivering the proposed SLIC technology to address the two most significant obstacles, SLLC will accelerate widespread commercial adoption of lightweight fiber composites in automotive vehicles, which will result in enormous environmental and economic benefits. A 10% reduction in vehicle weight can improve fuel economy by 6%8% and every 100kilogram decrease in the weight of a vehicle cuts emission by 35%, according to recent studies. With the 50% weight reduction target and the use of sustainable recyclable lowcarbonfootprint natural fibers and processes, SLIC is perfectly aligned with the U.S. goal of netzero carbon emission by 2050. Production of lightweight lowemission vehicles will reduce the carbon tax burden on automakers and stimulate investment for growth and highpay jobs to American workers. SLIC’s lowcost lightweight selfhealth monitoring functionalities will directly benefit consumers, who will enjoy lowered costs of vehicles, fuels, and maintenance. The vehicle weight reduction will also cause less stress on the nation’s aging bridge and roadway infrastructure, saving expenditures on maintenance. In addition to the automotive industry, SLIC also has a huge opportunity to meet the unmet needs for lightweight and highly reliable structural materials in the aerospace and renewable wind energy industries.