Low Velocity Impact Behavior of Glass Filled Fiber-Reinforced Thermoplastic Engine Components
This paper concerns automotive parts located underneath the engine and in particular the engine oil pan. Classically made of stamped steel or cast aluminum, new developments have allowed the manufacture oil pans with polyamide 66 reinforced by 35% weight of short glass fiber. However, polyamides have some limitations and the most significant is their response to localized impact loading. The nature of the impact considered here is of a typical stone collected from the road and projected into the oil pan. Low velocity impact investigations were carried out using a gas gun and drop weight tower. The study shows that the design of the oil pan has a significant contribution in the shock absorption. In addition to the material properties, the geometry and the ribbing both cleverly combined, increase the impact resistance of the component significantly. Areas of oil pan design improvement have been identified and conclusions drawn.
The Development of a Hybrid Thermoplastic Ballistic Material With Application to Helmets
Abstract : U.S. helmet material technology has changed relatively little since the introduction of aramids in the 1970s. All U.S. Army ballistic helmets use woven aramids with a thermoset (toughened phenolic) resin system. The current research explores the use of thermoplastic (polyolefin-based) matrix material. Although thermoplastic aramid systems have been evaluated for specialty applications, they have often failed to meet all the stringent criteria required of a U.S. Army helmet system. The present work seeks to remedy this by investigating hybrid ballistic material solutions. The combination of mass efficient ballistic and independent structural materials provides a means of meeting the spectrum of performance requirements demanded by U.S. Army helmet specifications. In addition to this, a series of helmet prototypes has been produced, which explore alternate design methods for selectively stiffening the core ballistic shell. Preliminary normalized performance data are presented that demonstrate the improved mass efficiency of the hybrid ballistic material solutions. This work summarizes the U.S. Army Research Laboratory's initial development of a candidate ballistic material solution to meet the Future Force Program requirements.
Annealing characteristics of ultraoriented high‐density polyethylene
The annealing characteristics of ultraoriented high‐density polyethylene fibers have been studied using differential scanning calorimetry, thermomechanical analysis, and tensile testing. The melting point of unannealed fibers was estimated to be 130 °C using a 10 °C min −1 heating rate. Fiber annealing between 126 and 132 °C split the melting endotherm into two peak melting at 132 and 139 °C. The weight fraction of fiber which had reorganized to the lower melting point increased with annealing time, finally attaining a constant value. However, annealing of laterally constrained fibers below 136 °C did not result in structural changes as detected by calorimetry. Melting‐point variations with heating rates≳0.625 °C min−1 indicated the equilibrium melting point of the unconstrained fiber at zero heating rate as 138 °C, while a similarly extrapolated value using heating rates <0.625 °C was ∼132 °C. The linear expansion coefficients rapidly increased near 132 °C and were attributed to the structural reorganiza...