Automotive Seat Research Articles

자동차용 유압식 시트댐퍼의 댐핑 메카니즘에 관한 연구

자동차용 유압식 시트댐퍼의 댐핑 메카니즘에 관한 연구

A Study on Automotive Seat Cushions having Multi-hardness Distribution for the Elderly

Objectives: Recent trends show an increase in driving by the elderly and most of them drive with a poor posture. In this study, not only the tests for body pressure but also the tests to identify characteristics of the seat itself were conducted. Methods/Statistical Analysis: Static load tests were conducted first to derive the seat-inherent characteristics such as deflection and hardness, etc. of the seat cushion as a function of loads for the automotive seat, and measurement tests for body pressure were conducted to secure body pressure data of the elderly. Combining the above two test results, final hardness values were obtained through which seat cushion pattern models having 8-hardness distributions could be derived. Findings: As a result, curves and functional equation for the two variables were derived through deflection as a function of measured loads. Also, hardness values at each point of the cushion could be found from the slopes of the curves mentioned, with the appearance of the phenomenon where the slope showed a steep increase in a particular region. This was affirmed to have occurred due to a difference in thicknesses of the cushion. Secondly, concentrated regions of body pressure per subject were affirmed and analyzed in the body pressure tests. By combining two test results, a total of 11 seat cushion pattern models could be derived, of which pattern analyses were conducted for 3 types observed with many personnel. Improvements/Applications: When the cushions are produced on the basis of the above pattern, it is considered possible to more ideally distribute the weight and to improve comfort upon seating compared with the commercial cushions.

Analyzing free and forced vibration of flexible polyurethane foam using multiple time scales method

Polyurethane foams are highly used in automotive and aerospace seats applications. In this study vibrational behavior of this foam is investigated. The dynamic of the system is cube of foam material, which is subjected to linear unidirectional motion. The foam is modelled as a single degree of freedom system. The governing equation of motion is an integro-differential equation. The novelty of the work is that multiple time scales method is used to study the approximate solution to the oscillation of the system. The motion of the system due to free and forced vibrations is identified. Primary resonances, non-resonant excitations, sub-harmonic and super harmonic cases were investigated. The response of system in each case is derived. Effects of viscoelastic parameters of foam on system behavior are then studied and the obtained results are illustrated through different figures.

The Contact Ageing Effect on Fretting Damage of an Electro-Deposited Coating against an AISI52100 Steel Ball.

This article investigates the effect of contact ageing on fretting damage of an epoxy-based cathodic electro-deposited coating for use on automotive seat slide tracks (made of cold-rolled high strength steel). Static normal load was induced at the contact between the coating and an AISI52100 ball for a certain duration. It was identified that plastically deformed contact area increased logarithmically as a function of time when the contact was under static normal load. Fretting tests after various durations of static contact were conducted using a ball-on-flat plate apparatus. All fretting tests were halted when the friction coefficient reached a critical value of 0.5, indicating complete coating failure. The total number of fretting cycles to the critical friction coefficient was found to vary with the duration of static contact before fretting. It was identified that the number of cycles to the critical friction coefficient decreased with the increased duration of static contact. Meanwhile, the friction coefficient at steady-state sliding was not greatly affected by the duration of static contact before fretting. Finally, the relation between coating thickness after indentation creep and the number of cycles to the critical friction coefficient was found to be linear. Obtained results show that the duration of static contact before fretting has an influence on the fretting lifetime of an electro-deposited coating.

Design concepts for an integrated whiplash mitigating head restraint and seat

ABSTRACTThis paper presents design of a concept for an integrated head restraint and car seat system to mitigate whiplash in rear-end vehicle collisions. The main emphasis is on a concept, which combines a reactive head restraint with a reactive seat. The chosen concept is developed in the form of mechanical linkages using linkage analysis software, SAM 6.1. A human model positioned in a ‘good’ driving posture is used to show how the head restraint and seat would operate using a typical crash pulse used for dynamic sled testing of automotive seats. The head restraint system is capable of translating into an optimal position of 40 mm forwards and 60 mm upwards in 12 ms, before whiplash-induced injuries start to take place. The reactive seat is also capable of reclining 15 degrees. The combination of reducing the backset and reclining the seat to reduce the relative motion between the head and torso has the potential to reduce the whiplash-effect-related injuries in rear-end collisions.

자동차용 고정밀 시트 리클라이너의 기어성형 공정에 관한 연구

In the automotive seat industry, the use of a fine blanking press is important for manufacturing of high precision products. Among them, a gear part which is a main component of an automotive seat recliner is generally manufactured by fine blanking press. However, the use of conventional mechanical press has been increasing in manufacture of gear part because of low productivity of fine blanking press. In this study, new forming process is suggested to fabricate the gear part with high precision by using mechanical press. The effect of flow restriction die (FRD) which has the restriction of blank edge on dimensional accuracy is investigated by FE-analysis. FE-analysis results for different conditions of FRD indicated that FRD has high dimensional accuracy with the lowest roll-over and the highest perpendicularity of gear part. After application to fabrication of the gear part using mechanical press, the measured dimensional characteristic was compared with the required specification of final product. In addition, results of the performance test showed that the product fabricated by developed process satisfied the required strength and durability. The results show that the suggested forming process by using FRD and mechanical press can replace fine blanking on the viewpoint of dimensional accuracy and productivity.

A Study on the Durability of Automotive Seat Frame with Aluminium

A Study on the Durability of Automotive Seat Frame with Aluminium

Flexible and Bio‐Based Nonisocyanate Polyurethane (NIPU) Foams

The amine cure of cyclic carbonate blends, derived from renewable resources and carbon dioxide, in the presence of a liquid fluorohydrocarbon as physical blowing agent with no ozone depletion potential, enables the facile tailoring of flexible bio‐based nonisocyanate polyurethane (NIPU) foams. Unlike conventional PU foams, neither isocyanates nor phosgene or aromatic amines are required as intermediates in NIPU foaming. Typically, rigid cyclic carbonates such as carbonated trimethylolpropane glycidylether (TMPGC) are blended together with the corresponding flexible cyclic carbonate such as ethoxylated TMPGC (EO‐TMPGC) which lowers monomer viscosity and reactivity. This is reflected by higher pot life and gelation times for the cure with hexamethylene diamine (HMDA), improving NIPU foam processing. With increasing EO‐TMPGC content, rigid TMPGC/HMDA‐NIPU foams are rendered flexible and soft, as verified by simultaneously declining storage modulus and glass transition temperature. In this NIPU foam family, the TMPGC/EO‐TMPGC (60 wt%/40 wt%) blend cured with HMDA in the presence of Solkane 365/227 affords flexible NIPU foams exhibiting low density, very good mechanical hysteresis, and tailored hardness, meeting the demands of various applications like automotive seating. Emission tests confirm the absence of critical compounds mentioned in the global automotive declarable substance list. image

Evaluation on structural characteristics of a lightweight automotive seat frame depending upon each thickness of material types

Evaluation on structural characteristics of a lightweight automotive seat frame depending upon each thickness of material types

The response of polymer optical fiber (POF) to bending and axial tension for the application of a POF sensor for automotive seat occupancy sensing

The automotive industry is a promising area for innovations in the field of polymer optical fiber (POF) sensors as the industry currently uses the POF mostly for data transmissions. Since an optical fiber sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference, it offers higher performance than that of its electrical-based counterparts such as the strain gage, elastomeric bladder, and resistive sensor systems. This enhanced performance makes an optical fiber sensor a suitable material for sensing seat occupancy for improved safety features in automobiles. The overall goal of this research is to develop a textile-based optical fiber sensor for automotive seat occupancy with high accuracy and reproducibility. In this study, the bending and tensile loading responses of POF were investigated, where two perfluorinated (PF) graded index (GI) POFs with two different core/cladding diameters, 62.5/750 and 62.5/490 μm, were used. The bending loss and the light attenuation against the applied axial stress were measured by a photon counting optical time-domain reflectometer. The critical bending diameters were analyzed: Cytop-1 (62.5/750 μm) ≥ 38.10 mm, Cytop-2 (62.5/490 μm) ≥ 44.45 mm. Furthermore, the elastic sensitive strain regions (x), where the stress-induced loss was recoverable, of the POFs at a 76.2 mm gage length at a strain rate of 4 mm/min were determined: Cytop-1: 3% ≤ x ≤ 3.5%, Cytop-2: 3.1% ≤ x ≤ 3.3%. The Cytop-1 was found to be less sensitive to bending and to have greater elastic sensitive strain range relative to the Cytop-2. In this study, a theoretical approach of the PF GI POF behavior to bending and axial tension was provided. The results demonstrated the feasibility of POFs as optical fiber sensors for automotive seat occupancy sensing.

Development and Validation of a High Anatomical Fidelity FE Model for the Buttock and Thigh of a Seated Individual.

Current practices for designing new cushions for seats depend on superficial measurements, such as pressure mapping, which do not provide sufficient information about the condition of sub-dermal tissues. Finite element (FE) modelling offers a unique alternative to integrate assessment of sub-dermal tissue condition into seat/cushion design and development processes. However, the development and validation of such FE models for seated humans requires accurate representation of the anatomy and material properties, which remain challenges that are yet to be addressed. This paper presents the development and validation of a detailed 3D FE model with high anatomical fidelity of the buttock and thigh, for a specific seated subject. The developed model consisted of 28 muscles, the pelvis, sacrum, femur, and one layer of inter-muscular fat, subcutaneous fat and skin. Validation against in vivo measurements from MRI data confirmed that the FE model can simulate the deformation of soft tissues under sitting loads with an accuracy of (mean±SD) 4.7±4.4mm. Simulation results showed that the maximum strains (compressive, shear and von-Mises) on muscles (41, 110, 79%) were higher than fat tissues (21, 62, 41%). The muscles that experienced the highest mechanical loads were the gluteus maximus, adductor magnus and muscles in the posterior aspect of the thighs (biceps femoris, semitendinosus and semimembranosus muscles). The developed FE model contributes to the progression towards bio-fidelity in modelling the human body in seated postures by providing insight into the distribution of stresses/strains in individual muscles and inter-muscular fat in the buttock and thigh of seated individuals. Industrial applications for the developed FE model include improving the design of office and household furniture, automotive and airplane seats and wheelchairs as well as customisation and assessment of sporting and medical equipment to meet individual requirements.

A textile- based optical fiber sensor design for automotive seat occupancy sensing

In our previous publications, the response of perfluorinated (PF) graded index (GI) POFs (62.5/750, 62.5/490 μm) to bending, tensile loading, and cyclic loading was investigated. The results showed that Cytop-1 (62.5/750 μm) was more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to Cytop-2 (62.5/490 μm). In this study, a textile-based optical fiber sensor was designed and the effect of automotive seat covering including face material and foam backing on a sensor’s performance was analyzed. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21 N/cm2, where PF GI POF (62.5/750 μm) was used as the POF material. The responses of the sensor in this interval were observed to be accurate and reproducible. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor response. Artificial neural network (ANN) was used for data analysis, and Qwiknet (version 2.23) software was used to develop ANNs. According to the results of Qwiknet, the prediction performances for training and testing data-sets were 75 and 83.33%, respectively.

The response of polymer optical fiber (POF) to cyclic loading for the application of a POF sensor for automotive seat occupancy sensing

The goal of this research aimed to develop an accurate and reproducible textile-based optical fiber sensor for automotive seat occupancy. In our previous publication, the response of perfluorinated (PF) graded index (GI) polymer optical fibers (POFs) (62.5/750 and 62.5/490 μm) to bending and tensile loading was investigated. In this study, the response of the PF GI POFs to cyclic loading was investigated. The repeated loading and unloading the POF sensor would experience due to car vibrations and multiple uses by seat occupants, might cause fatigue failure to the POF sensor. The results showed that the Cytop-1 did not show any permanent deformation up to 500 cycles at strain rates 4 and 60 mm/min at a gage length of 76.2 mm in its elastic sensitive strain region. The Cytop-2 showed permanent deformation at 3.5% strain after 500 cycles at a gage length of 76.2 mm. Thus, the Cytop-1 was found out to be more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to the Cytop-2. In this study, a theoretical approach of the behavior of PF GI POF to cyclic loading was also provided.

Prioritizing Sensor Performance Characteristics for Automotive Seat Weight Sensors in Quality Function Deployment (QFD)

Quality function deployment (QFD), a key tool to convert the customer needs into product features, is generally integrated into the New Product Development (NPD) process at the design stage. Prioritizing customer needs in a QFD process leads to using the resources (time, money, and staffing) effectively by eliminating the unimportant customer needs. The overall goal of the research was to develop a textile-based optical fiber sensor for automotive seat occupancy. The findings of this paper were focused on the design of experiments in our previous publication. In this paper, a research study was conducted to better understand market demands in terms of sensor performance characteristics for automotive seat weight sensors, as a part of the QFD House of Quality (HOQ) analysis. A survey was sent to more than 20 companies operating in the field of automotive seat weight sensors, and Original Equipment Manufacturers (OEM) via e-mail. Only five companies participated in this study due to competitive concerns and confidentiality reasons. However, the companies responded to the survey were of quality relevant to the research and could be perceived as representative of the group of experts. All 5 companies participated in the survey agreed on the first 5 most important sensor characteristics: reproducibility, accuracy, selectivity, aging, and resolution, where The Analytic Hierarchy Process (AHP) was applied to prioritize the sensor characteristics.

Safety design of automotive seat frame through structural analysis with fatigue and vibration

Safety design of automotive seat frame through structural analysis with fatigue and vibration

Structural analysis on variable characteristics of automotive seat frame by FEA

In this study, structural analysis for the seat frame of automotive was carried out using finite-element analysis (FEA) technique and comparative analysis of the designs of lightening method, while not degrading the strength and stability of the frame. Maximum equivalent stress and maximum deformation amount on the whole seat frame were analyzed by employing the loading condition of passengers on the back and cushion frames, which were made of steel as in the current seat frame of automotive. Moreover, an additional structural analysis of a seat frame that is made of carbon fiber reinforced plastic (CFRP), instead of the currently using steel material, was performed. The result of this analysis showed that the maximum displacement is increased when using CFRP, instead of steel. In addition, the lower density property of CFRP materials has the potential to reduce the weight of the frame when compared with that of the steel material. Therefore, this result suggests that the steel material that is being currently used in most automotive must be reduced. Overall, this study identifies the structural safety of the seat frame of automotive by comparing the distributed strength of different materials.

Optimal Integration of Alternative Energy Sources in Production Systems With Customer Demand Forecast

The objective of this paper is to develop an optimal planning framework for a production system utilizing multisource distributed energy supplies, in order to improve its energy efficiency and to reduce the dependency on grid energy and outage risk. The energy consumption of an automotive seat assembly plant is modeled using a discrete-event simulation, which consumes energy supplied by wind and solar, as well as traditional power grids. Machines can be halted for designed time period to avoid high peak load and operate efficiently in terms of power consumption. On the other hand, the inventory level can be planned by adjusting production goal to better utilize alternative energy and accommodate demand uncertainty using stochastic programming method. The results from case studies show that optimizing waiting time for each process can effectively reduce outage risk while meeting customer demands. Having the optimal production goal to over-produce when alternative energy supply is high can reduce the dependency on grid energy. Also, the benefit of considering predicted future customer demands would have the effect of safety inventory, which can prevent shortages during extremely high customer demand periods.

The Effects of Packaging on Collision Energy Absorption of Automotive Seat Headrest

The automotive seat headrest plays an important role in the passenger protection during car crashes, and its structure parameters and performance have direct influence on the seat crashworthiness. In this paper, according to relevant regulations of GB11550-2009, collision simulation analyses of the seat headrest structure were carried out by Ls-dyna code. The law of different headrest packaging parameters on collision energy absorption was investigated to provide guidance for the headrest structure optimization design and improvement. The research results show that, with the increase of packaging of the headrest, the maximum acceleration and high acceleration duration time of head gradually decreases.

English

English

Design concepts for an integrated whiplash mitigating head restraint and seat

ABSTRACTThis paper presents design of a concept for an integrated head restraint and car seat system to mitigate whiplash in rear-end vehicle collisions. The main emphasis is on a concept, which combines a reactive head restraint with a reactive seat. The chosen concept is developed in the form of mechanical linkages using linkage analysis software, SAM 6.1. A human model positioned in a ‘good’ driving posture is used to show how the head restraint and seat would operate using a typical crash pulse used for dynamic sled testing of automotive seats. The head restraint system is capable of translating into an optimal position of 40 mm forwards and 60 mm upwards in 12 ms, before whiplash-induced injuries start to take place. The reactive seat is also capable of reclining 15 degrees. The combination of reducing the backset and reclining the seat to reduce the relative motion between the head and torso has the potential to reduce the whiplash-effect-related injuries in rear-end collisions.