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Lemelson-RPI competition
Achievement/Results
This year IGERT student Casey Hoffman was chosen as a finalist for the prestigious Lemelson-RPI Student Prize. The $30,000 prize is awarded to a Rensselaer senior or graduate student who has created or improved a product or process, applied a technology in a new way, redesigned a system or in other ways demonstrated remarkable inventiveness.
Casey’s invention, Specialized Elastomeric Tooling (SET) for Advanced Thermoset Composites, is an entirely new method for curing advanced composites commonly used in the aerospace and biomedical industries. This patent-pending process replaces the need for expensive and energy inefficient autoclaves. The SET process results in at least an order of magnitude reduction in both energy consumption and capital expense. Advanced composites are now almost prohibitively expensive to manufacture, but with this technology could one day see wider use in more varied applications. The SET process consolidates and cures an advanced composite laminate by pressing it between a heated rigid mold and a computationally derived matching mold covered with an elastomeric (rubber) mask. A vacuum between the tools draws air bubbles from the composite preventing voids in the part. This process reduces curing and consolidation of thermoset advanced composites to its simplest requirements, i.e., providing the required hydrostatic pressure and uniform temperature to a formed layup.
The highly efficient method of direct conduction heating results in at least an order of magnitude improvement in energy consumption. The elastomer-faced half of the tooling must be specially designed so that the composite laminate is pressed with uniform hydrostatic pressure during curing, which ensures a cured part with uniform thickness and fiber volume ratio. SET innovates by adding intellectual value to the mold shapes, while keeping the process simple for implementation in industry. The optimal shape for the elastomeric mask and base mold are ascertained using gradient-based and genetic optimization algorithms in a finite element simulation.
In terms of energy consumption and cost of consumables, SET offers significant improvements over traditional autoclaving. The prolonged temperature and pressure ramp-up associated with autoclaving is essentially eliminated, because through-thickness heating of the uncured laminate by direct conduction from the heating tool is relatively instantaneous. In addition to reduced energy consumption, the time, expense, and waste associated with vacuum bagging and the associated consumables (e.g., vacuum bag material, sealing tape) are minimized considerably or even eliminated. SET is a closed process that does not require nitrogen to avoid the threat of explosion.
Finally, the energy, waste, and cost benefits scale proportionally with production volume without even considering the lack of equipment redundancy with autoclaving. SET lends itself well to production work because each mold can be used independently, and production capacity is not limited by the size of an autoclave. Rapid and low-cost manufacturing processes such as SET are the key to producing the industry’s most cutting-edge materials more affordably, safely and sustainably.
Address Goals
Energy is crucial to modern society, and we are running out of it. Hence, research that leads to dramatic decreases in use for the same processes are essential. This work could result in the nation becoming the global leader in this technology.
