: 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.
Safety and Comfort are the core requirements of the seating systems. Number of the occupants, determines type of the seating system requirement. The second row seat often needs to fold and slide, to allow the passenger to enter inside the car. Folding second row seat will also allow accommodating larger length cargo. The over folding of seat is controlled by hard stop mechanism. The hard stop mechanism generally consists of the seat arm stopper at back seat and hard stop located at base of the seat. These stoppers will limit the further motion of back seat. The folding speed of back seat is governed by various factors e.g. adjacent seat foam/structure friction, location, structural mass of seat etc. The scope of the paper is to evaluate various folding speeds of the back seat. Its effects are evaluated for the stresses and fatigue life of the hard stop components. The paper also discusses about CAE methodology used to setup the load case which replicates physical test setup.
Development of a Small Child Restraint System Virtual Surrogate to Evaluate CRS-to-Vehicle Interaction and Fitment
Automotive interior design optimization must balance the design of the vehicle seat and occupant space for safety, comfort and aesthetics with the accommodation of add-on restraint products such as child restraint systems (CRS). It is important to understand the breadth of CRS dimensions so that this balance can be successfully negotiated. Previously this was addressed with the advent of advanced air bag systems, when emphasis was placed on the design and development of surrogate child restraints, which were used, in developing and testing occupant sensing and classification systems. CRS design is constantly changing. In particular, the introduction of side impact protection for CRS as well as emphasis on ease of CRS installation has likely changed key design points of any child restraints. This ever-changing target puts pressure on the vehicle manufacturers to keep their vehicle seats and occupant space compatible.
Experimental Vibration Simulation for Heavy Duty Vehicle Seat Suspension with a Multiple-DOF Motion Platform
Abstract This paper presents a study on experimental vibration simulation using a multiple-DOF motion platform for heavy duty vehicle seat suspension test. The platform is designed to have 6-DOF with the advantages of high force-to-weight ratio, high dexterity and high position accuracy. It can simulate vehicle vibrations in the x, y and z translational axis and in the roll pitch and yaw axis rotation. To use this platform to emulate the real vibration measured from vehicle seat base under real operation for vehicle seat suspension test in lab, an Inertial Measurement Unit (IMU) is applied to collect the acceleration data from a real vehicle. An estimation algorithm is developed to estimate the displacement from the measured acceleration. The estimated displacement is then used to calculate the length of each leg of the platform so that the platform can generate the motion similar to the measured one.
Abstract Seat vibration when a vehicle is idling or in motion is an issue in automobile development. In order to reduce this vibration, dynamic damper or inertia mass is widely used. These countermeasures increases vehicle's weight and causes bad fuel-efficiency. Some new ways to reduce the vibration without weight increase are needed. One of that is the floating seat. Seat vibration has been reduced by controlling seat resonance frequencies. In order to control resonance frequency, the structures of the seat-mounting unit are replaced with floating structures using rubber bushings. It was demonstrated that partially replacing the mounting unit with floating structures makes it possible to control the resonance frequencies of the entire seat. The issue of balancing vibration reduction with strength and durability and crash safety performance caused by the fitting of rubber bushings to the seat-mounting unit was addressed using stopper structures optimized for each type of input.
This paper describes the design, prototyping, and validation approaches for interior subsystems of the Multi-Material Lightweight Vehicle (MMLV). Case studies are presented for two of the interior subsystems: the instrument panel/cross-car beam and the front seat structures. Both of these subsystems took advantage of the weight saving opportunities presented by carbon fiber reinforced composite materials. Analytical methodologies are detailed along with prototype build techniques for each. Design weight savings of 30% for the instrument panel/cross-car beam and 17% for the seat structures are achieved. Physical test results are presented that validate the design and the weight savings.
Abstract The lightweight seat of a high performance car is designed taking into account a rear impact, i.e. the crash due to an impulse applied from the rear. The basic parameters of the seat structure are derived resorting to simulations of a crash with a test dummy positioned on the seat. The simulations provide the forces acting at the seat structure, in particular the forces applied at the joint between the seat cushion and the seat backrest are taken into account. Such a joint is simulated as a plastic hinge and dissipates some of the crash energy. The simulations are validated by means of indoor tests with satisfactory results. A tool has been developed for the preliminary design of lightweight seats for high performance cars.
Abstract Driving posture measurement is essential for the evaluation of a driver workspace and for improved seat comfort design. This study captures the comfortable driving postures for Koreans using a handheld portable Artec L™ 3D scanner. Subjects consisted of 20 healthy individuals (10 males and 10 females) ranging in age from 20 to 40 years and grouped as three weight groups (<59 kg, 60-79 kg and >80 kg). Eighteen land markers were attached (car seat: 9 markers; subject: 9 markers). From the 3D scanned data, the angles (neck, back, headrest, seat back, wrist, elbow, knee, and ankle) and distances (head to headrest, seat height, and seat back and forth) between the land markers were extracted in the Rapidform XOR software. The body pressure distribution was measured using two pressure mats from 17 body part regions. The measured pressure data were analyzed for average pressure, contact area, and body part pressure ratio.
Abstract Optimizing climate seat systems requires increased complexity in seat design which in turn is driving a need for more detailed thermal simulation methods. This paper presents the model development considerations and results of a thermal simulation study aimed at improving the thermal seat comfort experience of Hyundai-Kia's heated seating systems.
Abstract This paper aims at Fiber Reinforced Panel or FRP mold and panel manufacturing of body panel and driver seat for a Formula Society of Automotive Engineers or FSAE racecar. The competition involves designing a Formula 1 type car that lays the standards for a high performance-racing car . This calls for a high Power: Weight ratio. The rules of the competition ensure a mandatory use of an air restrictor with an engine of a maximum capacity of 600cc to reduce the power of the engines . Hence, to compensate for the loss of power the target now shifts to minimizing the car's weight without compromising the strength. The body panel and driver's seat are two most valuable parts as the first adds elegance and aerodynamics to the car while the latter makes it comfortable for the driver to drive the car under high lateral load shifts. Weight reduction in this area is easier as strength is not the dominating factor.
Assessment of Compressive Thoracolumbar Injury Potential and Influence of Seat Cushions on Vertical Impact Loading of a Seated Occupant
Abstract Thoracolumbar vertebral fractures are most commonly due to compressive loading modes and associated with falls from height. Two injury metrics are generally referenced for assessing the potential for compressive thoracolumbar injury; the Dynamic Response Index (DRI) and the compressive load measured between the pelvis and lumbar spine using the Code of Federal Regulations (CFR) title 49 part 572 subpart B anthropomorphic test device (ATD). This study utilizes an ATD to investigate the injury mitigation potential of a variety of seat cushions during vertical impact in an unrestrained seated posture. ATD responses and DRI are reported for 65 vertical impacts with and without cushions from heights between 4 and 80 inches. The cushions investigated reduced ATD peak pelvic acceleration 63 +/− 11% and compressive lumbar load 42 +/− 9% on average.
The scope of this SAE Recommended Practice is to promote compatibility between child restraint systems and vehicle seats and seat belts. Design guidelines are provided to vehicle manufacturers for certain characteristics of seats and seat belts, and to child restraint system (CRS) manufacturers for corresponding CRS features so that each can be made more compatible with the other. The Child Restraint System Accommodation Fixture, shown in Figure 1, is used to represent a CRS to the designers of both the vehicle interior and the CRS for evaluation of each product for compatibility with the other. The features of the accommodation fixture are described as each is used. A CRS accommodation template of transparent plastic, not shown, represents the side of the accommodation fixture for use in approximating its installed position on design drawings.
Abstract Generally it is observed that in city buses most of the time, passenger seat fails at the seat mounting area in buses which are used for more than 3 years. This fatigue failure doesn't get captured either in Anchorage Test or Limited Vibration Test. Passenger seats' durability should be equal to vehicle life which is 10L km or 12 Years of life span. Physical testing on the vibration test rig is time consuming and costly. Most of the time machine availability for testing will be an issue, to validate alternate seat proposals. So there is a need to establish a correlation between physical testing and CAE simulation so that alternate proposals can be easily and quickly verified using CAE alone. This paper deals with the verification and validation of passenger seat in buses for life cycle requirement, through various methodologies adopted from data collection, CAE verification and physical validation to simulate real-time environment.
This document is a guide to the application of magnesium alloys to aircraft interior components including but not limited to aircraft seats. It provides background information on magnesium, its alloys and readily available forms such as extrusions and plate. It also contains guidelines for “enabling technologies” for the application of magnesium to engineering solutions including: machining, joining, forming, cutting, surface treatment, flammability issues, and designing from aluminum to magnesium.
This SAE Recommended Practice describes two-dimensional 95th percentile truck driver side view, seated stomach contours for horizontally adjustable seats (see Figure 1). There is one contour and three locating lines to accommodate male-to-female ratios of 50:50, 75:25, and 90:10 to 95:5.
This SAE Recommended Practice describes two-dimensional, 95th percentile truck driver, side view, seated shin-knee contours for both the accelerator operating leg and the clutch operating leg for horizontally adjustable seats (see Figure 1). There is one contour for the clutch shin-knee and one contour for the accelerator shin-knee. There are three locating equations for each curve to accommodate male-to-female ratios of 50:50, 75:25, and 90:10 to 95:5.
The Automotive Seating Systems Report from IHS SupplierBusiness takes an in-depth look at the global seating market including the key changes currently underway in the industry and what the future holds for this sector. The report considers in-house seat manufacture and supply chain developments along with advances in safety, comfort and convenience. Fitment rates for various seat features such as powered and memory functions, lumbar support and massage have been increasing and will continue to do so as vehicle interiors become “smarter”. Much of the technology in today’s seats is electric or electronically driven, and can be remotely controlled via links on the dashboard or controllers located throughout the vehicle. The market is opening up to New Tier 1 suppliers as well as Tier 2 and specialist niche technology players, all of whom will intensify the competition for supplying the world’s leading seating companies.
This recommended practice is a source of information for body and trim engineers and represents existing technology in the field of on-highway vehicle seating systems. It provides a more uniform system of nomenclature, definitions of functional requirements, and testing methods of various material components of motor vehicle seating systems.
Define and develop test parameters, test methods, measurements, and acceptable performance criteria for composite aircraft seat structures.
2015 engines ride a technology tidal wave Powertrain engineers are diving deeper to find new ways to make light-duty power units more efficient without compromising performance. Connectivity for comfort Seat suppliers such as Continental, Johnson Controls, and Faurecia pursue 'networked' seats to enhance safety, personalization, and comfort. Assembling aluminum vehicles in volume Ford's 2015 F-150 pickup pioneers high-volume mass-production of lightweight aluminum car and truck structures.
This SAE Aerospace Recommended Practice (ARP) documents a common understanding of terms, compliance issues and occupant injury criteria to facilitate certification of oblique facing seat installations specific to Part 25 aircraft.
This SAE Recommended Practice specifies performance requirements and test procedures for the strength and location of seat belt assembly anchorages. It applies to seat belt anchorages attached to vehicle body structure or to seat assemblies in the vehicle. Design Considerations are specified in SAE J383.
Abstract The automotive industry needs sustainable seating products which offer good climate performance and superior seating comfort. The safety requirement is always a concern for current seating systems. The life of the present seating system is low and absorbs moisture over a period of time which affects seat performance (cushioning effect). Recycling is one of the major concerns as far as polyurethane (PU) is concerned. This paper presents the development of an alternative material which is eco-friendly and light in weight. Thermoplastic Polyolefin (PO) materials were tried in place PU for many good reasons. It is closed cell foam which has better tear and abrasion resistance. It doesn't absorb water and has excellent weathering resistance. Also it has a better cushioning effect and available in various colours. Because of superior tear resistance, it is possible to eliminate upholstery and would reduce system level cost.
This recommended practice describes boundaries of hand control locations that can be reached by a percentage of different driver populations in passenger cars, multi-purpose passenger vehicles, and light trucks (Class A vehicles). This practice is not applicable to heavy trucks (Class B vehicles).
Methods will be developed to characterize In Flight Entertainment (IFE) component impact performance separate from seat design. These methods will address both initial seat head impact criterion (HIC) testing and subsequent IFE component changes. Methods will evaluate head blunt trauma, post-impact sharp edges, and egress impediment. Criteria development will involve defining test methods, test parameters, measurements, and acceptance criteria. Particular emphasis on evaluating IFE changes that require coordination and evaluation per SAE ARP 6448, Appendix B.
This document provides informational background, rationale and a technical case to allow consideration of the removal of the magnesium alloy restriction in aircraft seat construction as contained in AS8049B. The foundation of this argument is flammability characterization work performed by the FAA at the William J. Hughes Technical Center (FAATC), Fire Safety Branch in Atlantic City, New Jersey, USA. The rationale and detailed testing results are presented along with flammability reports that have concluded that the use of specific types of magnesium alloys in aircraft seat construction does not increase the hazard level potential in the passenger cabin in a post-crash fire scenario. Further, the FAA has developed a lab scale test method, reference DOT/FAA/TC-13/52, to be used as a certification test, or method of compliance (MOC) to allow acceptability of the use of magnesium in the governing TSO-C127 and TSO-C39C.
This SAE Aerospace Recommended Practice (ARP) provides guidance for the design and location of flight attendant stations, including emergency equipment installations at or near such stations, so as to enable the flight attendant to function effectively in emergency situations, including emergency evacuations. Recommendations regarding design of flight attendant stations apply to all such stations; recommendations regarding location apply to those stations located near or adjacent to floor level exits.
This SAE Recommended Practice encompasses the significant factors which determine the effectiveness of a seat system in limiting spinal injury during vertical impacts between the rider and the snowmobile seat system. The document is intended to provide a tool for the development of safer snowmobile seats. It is recognized that the seat is only a portion of the entire vehicle protective suspension system. It is, however, usually required that the seat serve as added protection to the suspension system, since the latter may "bottom out" during a severe impact. The term "seat" refers to the occupant-supporting system not normally considered part of the vehicle suspension or frame system. In some cases, it may include more than the foam cushion.
In vehicle driving environment, the driver is subjected to the vibrations in horizontal, vertical, and fore-aft directions. The human body is very much sensitive to whole body vibration and this vibration transmission to the body depends upon various factors including road irregularities, vehicle suspension, vehicle dynamics, tires, seat design and the human body's properties. The seat design plays a vital role in the vibration isolation as it is directly in contact with human body. Vibration isolation properties of a seat depend upon its dynamic parameters which include spring stiffness and damping of seat suspension and cushion. In this paper, an optimization-based method is used to determine the optimal seat dynamic parameters for seat suspension, and cushion based on minimizing occupant's body fatigue (occupant body absorbed power). A 14-degree of freedom (DOF) multibody biodynamic human model in 2D is selected from literature to assess three types of seat arrangements.
Abstract In terms of the responsive quality of cars, reducing the vibration of car seats is very important, as this vibration is transmitted directly to the driver. Here, a sensitivity analysis method was used to reasonably reduce the vibration of car seats at minimal cost. A laboratory test was conducted under two excitation conditions: first, vibration in idle state; second, random vibration not exceeding 100 Hz. To determine the reliability of the laboratory test, the actual vibration in idle state was simulated in a multi-axial simulation table for the idle excitation environment of cars that are sensitive to even the smallest changes in the environment. The frequencies of interest were selected by adding the sums of frequency response functions measured at the 24 nodal points of interest under the two excitation conditions.