Seat vibration when the vehicle is idling and when it is in motion has been reduced by using a floating seat that controls the resonance frequencies. The resonance frequency is controlled by replacing the structures of the seat-mounting unit with floating structures using rubber bushings. Partly 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 due to fitting rubber bushings to the seat-mounting unit was addressed using stopper structures optimized for each type of input. To adopt a floating seat into an actual vehicle, the floating structure and conventional foot bracket are combined. This combined foot bracket not only makes it easy to assemble floating structure into the seat, but also makes it possible to keep the seat weight almost the same as a conventional seat.
Comfort-driven design of car interiors: a method to trace iso-comfort surfaces for positioning the dashboard commands
General comfort may be defined as the “level of well-being” perceived by humans in a working environment. The state-of-the-art about evaluation of comfort/discomfort shows the need for an objective method to evaluate the “effect in the internal body” and “perceived effects” in main systems of comfort perception. Some medical studies show that each human joint has its own natural Rest Posture (RP); in this Rest Posture human muscles are completely relaxed or at minimum strain level: when it happens the geometrical configuration corresponds to the natural position of resting Arms/Legs/Neck etc.. From this starting point, authors developed and build, through a wide experimental campaign, the postural-comfort curves for each DOF of human upper limbs joints; the obtained comfort curves are regular and don’t show any kind of discontinuity. A software named Ca-Man has been developed in order to analyze a general posture and calculate a postural comfort index for the entire upper body.
The lightweight seat of a high performance car is designed taking into account a rear impact. The basic parameters of the seat structure are derived resorting to the simulation of a crash test. A dummy is positioned on the seat and subject to a rear impulse. The simulations provide the dynamic loads acting on the seat structure, in particular the ones applied at the joint between the seat cushion and the seat backrest. Such a joint is simulated as a plastic hinge and dissipates some of the crash energy. By means of the simulations the proper parameters of the plastic hinge can be derived to design a safe seat. The simulations are validated by means of indoor tests with satisfactory results. By using the validated model, the influence of seat cushion and backrest parameters on seat passenger's injury are studied. An efficient tool has been developed for the preliminary design of lightweight seats for high performance cars.
: 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.
Experimental vibration simulation for heavy duty vehicle seat suspension with a multiple-DOF motion platform
Heavy duty vehicles suffer from detrimental vibrations which have significant influence to the operator’s comfort, health and safety. Especially, long term exposures to vibration with a frequency range between 0.5 and 10Hz will severely damage the driver’s backbone. Tires, chassis suspension and seat suspension are three traditional methods to isolate vehicles vibration, but it is generally difficult to modify the parameters of tires and chassis suspension, even many approaches are proposed for the performance of chassis suspension. On the other hand, the seat suspension system is easy to modify and optimize. Therefore, seat suspension has been employed as a simple and effective method to isolate vehicle vibration transmitted to the driver’s body. Studying the vibration characteristics of seat suspension is one important step for seat suspension design.
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.
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 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 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.
Abstract Vibration is both a source of discomfort and a possible risk to human health. There have been numerous studies and knowledge exists regarding the vibrational behavior of vehicle seats on adult human occupants. Children are more and more becoming regular passengers in the vehicle. However, very little knowledge available regarding the vibrational behavior of child safety seats for children. Therefore, the objective of this study was to measure the vibrations in three different baby car seats and to compare these to the vibrations at the interface between the driver and the automobile seat. The test was performed on the National road at the average speed of 70 km/h and acceleration levels were recorded for about 350 Sec (5.83 min). One male driver considered as an adult occupant and a dummy having a mass of 9 kg was representing one year old baby. Four accelerometers were used to measure the vibration. All measured accelerations were relative to the vertical direction.
Abstract Seat comfort is an important factor in the development of a vehicle; however, comfort can be measured in many ways. Many aspects of the experimental design such as the duration of the drive test, the questions asked, and the make-up of the test subjects are known to influence comfort results. This paper provides the background methodology and results of a Seat comfort study aimed at assessing long-term driving seat comfort.
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.