Simulation-based assessment for construction helmets and clothing
In recent years there has been a push for greater job safety in all industries. Personnel protective equipment or PPE has been developed to help mitigate the risk of injury to humans that might be exposed to hazardous situations. The human head is the most critical location for impact to occur on a work site. A hard enough impact to the head can cause serious injury or death. That is why industries have adopted the use of an industrial hard hat or helmet. The objective of this safety device is to reduce the risk of injury to the head. There has only been a few articles published that are focused on the risk of head injury when wearing an industrial helmet. A lack of understanding is left on the effectiveness of construction helmets when reducing injury. The scope of this study is to determine the threshold at which a human will sustain injury when wearing a helmet. Complex finite element, or FE, models were developed to study the impact on construction helmets. The FE model consists of two parts the helmet and the human model. The human model consists of a brain, enclosed by a skull and an outer layer of skin. The level and probability of injury to the head is determined using both the Head Injury Criterion (HIC) and tolerance limits set by Deck and Willinger. The HIC has been greatly used to assess the likelihood of head injury while in a vehicles. The tolerance levels proposed by Deck and Willinger are more suited for finite element models, but lack wide scale validation. Different cases of impact were studied using LSTC’s LS-DYNA. In this thesis a study was conducted that assesses the risk of injury for wearers of construction helmets or hard hats. Next a literature survey on clothing simulation was also completed. Cloth modeling and simulation has gained significant momentum in recent years due to advances in computational hardware and software. Cloth plays an important role not only in daily life, but also in special scenarios such as firefighter clothing, ballistic or bullet proof vest and space suits. There are special requirements such as the protective capability of the fabric and effects on mobility for the wearer of the particular fabric or garment. Traditional assessment of cloth is to develop prototypes first and conduct experiments to assess the garment. This is time consuming and expensive. Virtual cloth modeling and simulation provides a means to demonstrate and assess its performance before cloth is made. This study attempts to give a literature review to summarize the state-of-the-art of cloth modeling and simulation. After the literature survey several clothing simulations were completed using LS-Dyna. These simulations were able to test and predict some basic information. The testing showed that realistic draping and stress mapping for digital cloth can be achieved using LSTC’s LS-Dyna.