Mechanical evaluation of polymer composite hip protectors

Abstract

Hip fractures often result in serious health implications, particularly in the geriatric population, and have been related to long-term morbidity and death. In most cases, these fractures are caused by impact loads in the area of the greater trochanter, which are produced in a fall. This work is aimed at developing hip protectors using composite materials and evaluating their effectiveness in preventing hip fractures under high impact energy (120 J). The hip protectors were developed with an inner layer of energy absorbing soft material and an outer rigid shell of fiberglass-reinforced polymer composite. According to the experimental results, all tested configurations proved to be effective at reducing the impact load to below the average fracture threshold of proximal femur. Furthermore, an addition of Ethylene Vinyl Acetate (EVA) to the impacted area of the composite shell proved to be beneficial to increase impact strength of the hip protectors. Thus, composite hip protectors proved to be a viable alternative for a mechanically efficient and cost-effective solution to prevent hip fractures.

Figure 1

Composite hip protectors.

Figure 2

Schematic of the impact test equipment.

Figure 3

Impact test equipment.

Figure 4

Macroscopic and microscopic (SEM) details of the fracture (2 layers).

Figure 5

Composite hip protector with three layers on the reinforced shell.

Figure 6

Hip protectors fabricated with one layer of glass fiber chopped strand mat and gel coat with EVA particles content of 10 wt. %, after impact load.

Figure 7

Impact tests data showing the impact on the surrogate greater trochanter (direct impact), the impact on the surrogate greater trochanter covered by the soft tissue, and the impact on the three hip protectors configurations. Error bars represent plus or minus one standard deviation.