: Low back pain has a higher prevalence among drivers who have long term history of vehicle operations. Vehicle vibration has been considered to be a causative factor associated with low back pain; however, the fundamental mechanism that relates vibration to low back pain is still not clear. It is hypothesized that vibration causes vibration in the muscles at resonant frequencies, leading to increased muscle activity and muscle fatigue during prolonged driving. The aim of this study was to determine the vibration frequency that causes the increase of muscle activity that can lead to muscle fatigue and low back pain. This study investigated the effects of various vibration frequencies on the lumbar and thoracic paraspinal muscle responses among 11 seated volunteers exposed to sinusoidal whole body vibration varying from 4Hz to 30Hz. The accelerations of the seat and the pelvis were recorded during various frequency of vibrations.
Abstract Discuss the basics of posturing and positioning of the full range of occupants necessary to cover the required anthropometric demographics in combat vehicles, both ground and air, since there are similarities to both and that they are both very different than the traditional automotive packaging scenarios. It is based on the Eye Reference Point and the Design Eye Point. Discuss the three Reach Zones: Primary, Secondary and Tertiary. Discuss Vision Zones and potentially ground intercepts. Discuss body clearances, both static and dynamic. Discuss the basic effects of packaging occupants with body armor with respect to SRP's and MSRP's.
Abstract Seating comfort is one of the most important indicators of the performance of automotive seats. The objective and subjective evaluation of seating comfort plays an important role in the development of seating systems. Objective methods are primarily based on evaluating the influence of vibrations on the driver's seat and assessing the seat pressure ratio. The primary goal of this study was to evaluate the comfort of two car seats (sedan and compact) by comparing a subjective technique with an objective technique like body pressure ratio for a sample of 12 subjects. The results show that the pressure ratio for IT (ischial tuberosity) and L4/L5 were significantly greater for the seat of a compact car than the seat of a sedan car. The subjective comfort was significantly greater for the seat of the sedan car and females than the seat of the compact car and males, respectively.
This paper presents a PC based mathematical and rapid prototyping technique for anthropometric accommodation in a maintenance environment using the principle of simulation based design. The developed technique is capable of analyzing anthropometric data using multivariate (Principal component Analysis) approach to describe the body size variability of any given population. A number of body size representative cases are established which, when used properly within the constraints of the maintenance environments, will ensure the accommodation of a desired percentage of a population. This technique evaluates the percentage accommodation of a given population for the environment using the specific manikin cases as boundary conditions. In the case where any member of a maintenance crew cannot be accommodated, the technique has the capability of informing the designer of the environment why the member(s) is/are not accommodated.
Development of a Legform Impactor with 4-DOF Knee-Joint for Pedestrian Safety Assessment in Omni-Direction Impacts
The issue of car-to-pedestrian impact safety has received more and more attention. For leg protection, a legform impactor with 2 degrees-of-freedom (DOF) proposed by EEVC is required in current regulations for injury assessment, and the Japan Automobile Manufacturers Association Inc. (JAMA) and Japan Automobile Research Institute (JARI) have developed a more biofidelic pedestrian legform since 2000. However, studies show that those existing legforms may not be able to cover some car-to-pedestrian impact situations. This paper documents the development of a new pedestrian legform with 4 DOFs at the knee-joint. It can better represent the kinematics characteristics of human knee-joint, especially under loading conditions in omni-direction impacts. The design challenge is to solve the packaging problem, including design of the knee-joint mechanisms and layout of all the sensors in a limited space of the legform.
Many research groups are developing Human Body FE Models (FE-HBM) as a tool to be used in safety research. The FE-HBM's currently available are in certain fixed postures. Repositioning of model in alternate postures is needed for use in out of position (OOP) occupant simulations and different pedestrian posture simulations. Postural change in upper extremity can be split two processes, viz, repositioning of spinal vertebra and repositioning of the soft tissue associated with the spine. The objective of this study is to establish a methodology to regenerate pelvis flesh with change in spine/pelvis position. The outer profile of the pelvis flesh should ideally be parametrically described with respect to the associated hard tissues which is not the case in existing FE-HBM's. The affine invariant (Farin, 1990) property of cubic Bezier curves is used in this study.
Anthropometric data of a country is vital database for automotive design and other design applications. It is also an important parameter in population studies. Most developed countries have invested resources over the years to develop such a database and this information is accessed by many OEMs and major Design Houses. However, an updated and comprehensive Anthropometry of Indian Population is largely unknown. In the past, a few institutions have done projects to bring out a picture of the Indian Anthropometry. However, keeping in view the rapid industrialization and increase of India-specific designs which require an access to latest Anthropometric database, the project “SIZE INDIA” has been initiated. For the first time in India, a state of the art 3D Whole body scanner technology has been used and thereby large volume of data has been generated in a very short span of time.
The objective of this study was to evaluate the geometry of a wide range of restraints (child restraints, booster seats and rear seats) used by children, and how these match their anthropometry, and to determine limitations to restraint size for the population of children using them. The study is motivated by the widespread premature graduation from one restraint type to another, which parents often attribute to children outgrowing their previous restraint. Currently, recommended transitions are based on a small sample of vehicles and children. Outboard rear seat and seat belt geometry (anchorage locations, sash belt angles) from 50 current model vehicles were measured using a custom-developed measuring jig. For 17 child restraints, a 3-dimensional measuring arm was used to measure the geometry of the restraint including interior size and strap slot locations (where relevant).
Two manufacturers, Denton ATD and FTSS, currently produce the Hybrid III 5th percentile female dummy. In response to concerns raised by industry that differences in the anthropometry of the molded breasts between the two manufacturers may influence chest responses, Transport Canada conducted a comparative testing program. Thorax biofidelity tests were conducted to compare force-deflection characteristics; full-frontal, rigid-barrier tests were conducted at 40, 48 and 56 km/h to compare chest responses, and out-of-position chest on module static airbag deployment tests were conducted to compare peak chest deflections of the Denton and FTSS dummy jackets and of a prototype jacket without breasts. Differences in force-deflection characteristics were observed during biofidelity pendulum impacts of the two dummies, with much of the differences attributed to the different chest jackets.
The purpose of this study was to determine scale factors for small, mid-size and large adults using a caprine model. In a previous study conducted in our lab, scaling relationships were developed to define cervical spine tolerance values of children using caprine specimens. In that study, tolerances were normalized with respect to an average adult. Because airbag-related injuries are associated with out-of-position children and small adult females, additional experimental data are needed to better estimate human tolerance. In the present study, cervical spine radiographs from the 5th, 50th and 95th percentile human adults were used to determine vertebral body heights for small, mid-size and large anthropometries. Mean human vertebral body heights were computed for each anthropometry and were normalized with respect to mid-size anthropometry.
This paper reports on a cooperative research project between the Australian Department of Transport and Regional Services and Transport Canada. This project was a parametric study aimed at better understanding the effects on side impact injury risk of: trolley mass; barrier stiffness; barrier stiffness distribution; barrier face height above ground; crabbed or perpendicular impact; and impact Speed. The following observations on injury risk can be made from the tests: the 2 largest effects for the driver are increasing the height of the barrier face (mainly thoracic) and test speed (all body regions). Increasing the trolley mass, with a bullet / target mass ratio less than 1, has the effect of increasing only the pubic force. Doubling the barrier stiffness increases injury risk in only the pelvic area. The custom high and stiff element (attempting to replicate an SUV) increases both pelvic and abdominal loading.