Search Results

This paper contains a review of current information on biological structure, material properties and failure characteristics of bone, articular cartilage, ligament and tendon. The load-deformation response of biological tissues is presented with particular reference to the microstructure of the material. Although many of the tissues have been characterized as linear, elastic and isotropic materials, they actually have a more complicated response to load, which includes stiffening with increasing strain, inelastic yield, and strain rate sensitivity. Failure of compact and cancellous bone depends on the rate, type, and direction of loading. Soft biological tissues are vlscoelastie and exhibit a higher load tolerance with an increasing rate of loading. The paper includes a discussion on the basic principles of biomechanics and emphasizes material properties and failure characteristics of biological tissues subjected to impact loading.

Life threatening chest injury can involve partial or full tears of the aorta. Investigations of fatal injuries in automobile accidents indicate that aortic trauma occurs in 10-20% of the cases. The major sites of aortic trauma include the aortic isthmus, the root, and the aortic insertion at the diaphragm - all of which are points of aortic tethering. The biomechanics of the injury process involve stretching of the vessel from points of tethering and hydrodynamic increases in blood pressure, which stretch the tissue to failure at a strain of about 150%. The non-isotropic stretch response of aortic tissue is discussed with reference to the frequent transverse orientation of the laceration. Congenital and pathophysiological conditions also influence the failure characteristics of the tissue. The significant factors associated with traumatic injury of the aorta are discussed in this review paper which is based on published technical information.

Knee bolsters on the lower instrument panel have been designed to control occupant kinematics during sudden deceleration. However, a wide variability in car occupant anthropometry and choice of seating posture indicates that lower-extremity contacts with the impingement bolster could predominantly load the flexed leg through the knee (acting through the femur) or through the tibia (acting through the knee joint). Potential injuries associated with these types of primary loading may vary significantly and an understanding of potential trauma mechanisms is important for proper occupant restraint.

Obesity rates are reaching an epidemic worldwide. In the US, nearly 40 million people are obese. The automotive safety community is starting to question the impact of obesity on occupant protection. This study investigates fatality and serious injury risks for front-seat occupants by Body Mass Index (BMI). NASS-CDS data was analyzed for calendar years 1993-2004. Occupant exposure and injury was divided in seven BMI categories with obese defined as those with BMI ≥ 30 kg/m2. Injuries were studied for drivers and right-front passengers and included analysis of lap-shoulder belted and unbelted occupants. The results show that obese occupants have a higher fatality risk compared to normal BMI occupants; morbidly obese occupants (BMI ≥ 40 kg/m2) have 2.25 times higher fatality risk (1.15% v 0.51%). The fatality risk for belted obese drivers was 0.29%, which was 6.7 times lower than the 1.94% for those unbelted. These rates are similar to other BMI occupants.

Objective: This study addresses severe injury risks in rear impacts for front-outboard occupants using the seatback incline variable in NASS-CDS. Methods: Severe injury risk (MAIS 4+F) was determined for front-seat occupants in rear impacts involving passenger cars from 1995–2006 NASS-CDS data. The risk of severe injury to front-seat occupants was determined as a function of the rotated position of the seatback and crash severity in three delta V ranges: <20, 20–30, >30 mph. The data was also analyzed for newer model vehicles (≥1997 MY) to assess changes with newer seats and head restraints. The effects of seatbelt use, occupant age and BMI (Body Mass Index) were also examined. Individual NASS-CDS electronic cases were also reviewed with MAIS 4+F injury. There were 25 injured occupants in rotated seats and 46 in non-rotated seats. Results: Severe injury risk for front-seat occupants in rear impacts is lower with a rotated seatback in the most severe rear crashes.

This paper covers the development of the General Motors Energy Absorbing Steering System beginning with the work of the early crash injury pioneers Hugh DeHaven and Colonel John P. Stapp through developments and introduction of the General Motors energy absorbing steering system in 1966. evaluations of crash performance of the system, and further improvement in protective function of the steering assembly. The contributions of GM Research Laboratories are highlighted, including its safety research program. Safety Car, Invertube, the biomechanic projects at Wayne State University, and the thoracic and abdominal tolerance studies that lead to the development of the Viscous Injury Criterion and self-aligning steering wheel.

This paper reviews issues relating to seats including design for comfort and restraint, mechanics of discomfort and irritability, older occupants, and low-back pain. It focuses on the interface between seating technology and occupant comfort, and involves a technical review of medical-engineering information. The dramatic increase in the number of features currently available on seats outreaches the technical understanding of occupant accommodation and ride comfort. Thus, the current understanding of seat design parameters may not adequately encompass occupant needs. The review has found many pathways between seating features and riding comfort, each of which requires more specific information on the biomechanics of discomfort by pressure distribution, body support, ride vibration, material breathability, and other factors. These inputs stimulate mechanisms of discomfort that need to be quantified in terms of mechanical requirements for seat design and function.

Five anesthetized porcine subjects were exposed to blunt thoracic impact using a 21 kg mass with a flat contact surface traveling at 3.0 to 12.2 m/s. The experiments were conducted to assess the appropriateness of studying in vivo mechanical and physiological response to thoracic impact in a porcine animal model. A comprehensive review of comparative anatomy between the pig and man indicates that the cardiovascular, respiratory and thoracic skeletal systems of the pig are anatomically and functionally a good parallel of similar structures in man. Thoracic anthropometry measurements document that the chest of a 50 to 60 kg pig is similar to the 50th percentile adult male human, but is narrower and deeper. Peak applied force and chest deflection are in good agreement between the animal's responses and similar impact severity data on fresh cadavers.