Seat Back Research Articles

Evaluation of mechanical properties of natural fiber based polymer composite

Natural fiber based polymer composites are eco-friendly alternatives to synthetic materials, with greater mechanical properties, biodegradability, availability, ease of access, and affordability. Jute fiber is widely recognized as one of the most important and beneficial natural fibers due to its strength, durability, and biodegradability. In this study, the jute composite is designed and fabricated using a 5-layer jute and epoxy resin, utilizing the manual hand lay-up technique. The combination of 52.5 % jute and 47.5 % of epoxy resin and harder is found optimized to achieve the goals of improving the tensile strength and flexural strength, reducing the cost of epoxy resin, and promoting eco-friendliness and sustainability. Tensile testing was performed on a universal testing machine, while flexural testing was done with a three-point bending test. Experimentally, the composites reinforced with jute and epoxy resin were capable of achieving the required levels of tensile strength (42.91 MPa) and bending strength (69.30 MPa). To validate and visualize specimens, numerical analysis was performed on the ABAQUS simulation software. The numerical simulation utilized ASTM D3039 and ASTM D7264 as the specified requirements for tensile and flexural behavior. For validation, these tensile and flexural test results were then numerically analyzed and compared to the experimental data. Finally, composite design, fabrication, and optimization can improve mechanical properties, reduce composite weight, lower resin cost, and increase sustainability. The proposed design and composition can be implemented to achieve lightweight properties in various applications, such as car components, door handle sheets, bicycle seat backs, and luggage covers.

Failure analysis and optimization design of CFRP automotive seat back under multiple conditions

This study explores the adoption of carbon fiber reinforced plastic (CFRP) in automotive seat backrests, aiming to improve compliance with regulatory standards and enhance performance. By replacing conventional materials with CFRP, and employing mechanical performance tests alongside the principle of equal stiffness, the study tackles material failure issues. A novel multi-criteria decision-making method, coupled with an optimal Latin hypercube experimental design, is used to optimize the layup sequence. The optimized design not only meets regulatory requirements but also significantly enhances driver and passenger safety and comfort during collisions.

WITHDRAWN: An Experimental and Numerical Approach to Evaluate Mechanical Properties of Jute Fiber-Based Polymer Composites

One of the best natural fibers is jute fiber because of its availability, ease of access, and affordability. It has some highly intriguing qualities, including biodegradability and high strength. In this study, the jute composite is designed and fabricated using a 5-layer jute and epoxy resin, utilizing the manual hand lay-up technique. The combination of 52.5% jute and 47.5% of epoxy resin and harder is found optimized to achieve the goals of improving the tensile strength and flexural strength, reducing the weight of the composite, reducing the cost of epoxy resin, and promoting eco-friendliness and sustainability. Tensile testing was performed on a universal machine, while flexural testing was done with a three-point bending test. Experimentally, the composites reinforced with jute and epoxy resin were capable of achieving the required levels of tensile strength (42.91 MPa) and bending strength (69.30 MPa). To validate and visualize specimens, numerical analysis was performed on the ABAQUS simulation software. The numerical simulation utilized ASTM D3039 and ASTM D7264 as the specified requirements for tensile and flexural behavior. For validation, the results of these tensile and flexural tests were then numerically analyzed and compared to the experimental data. Finally, the composite design, fabrication, and optimization can improve mechanical properties, reduce composite weight, lower resin cost, and increase sustainability. The proposed design and composition will be implemented to achieve lightweight properties in various applications such as car components, door handle sheets, bicycle seat backs, and luggage covers.

The Impact of Meaningful Vibrotactile Displays on User Preferences Across Age Groups in Automated Driving

Automated vehicles may enhance the quality of life by empowering individuals and promoting independent mobility, especially for older adults. However, takeovers are still required occasionally. To ensure a safe transition during the takeover, meaningful tactile displays as takeover requests could be a good option to improve takeover efficiency. Previous studies have examined the effects of tactile takeover request more from an objective perspective, however, subjective evaluations that could reach larger and more diverse sample sizes have not been extensively conducted yet. Therefore, the goal of this study was to investigate drivers of different age groups (younger and older adults) on their preference of vibrotactile displays, varied in information formats (instructional and informative) and locations (seat back and seat pan), on a large population scale ( n = 353) through a national survey. The results indicated a preference for informative patterns over instructional patterns and displays on the seat back over the seat pan. Also, a higher level of perceived urgency was noted in older participants (age ≥ 65) compared with younger participants. These findings may inform the design of next-generation tactile interfaces in automated systems.

Development of sunflower husk reinforced polypropylene based sustainable composites: An experimental investigation of mechanical and thermal performance

AbstractClimate change, shrinking resources, and rising raw material costs have pushed the industry to create more sustainable, and lightweight materials. Natural fiber composites are materials of interest for replacing conventional materials such as steel. Sunflower husks (SH), among many other natural fibers, are readily accessible as agricultural waste and have advantageous properties. In this study, sunflower husks were mixed with polypropylene (PP) matrix using a twin‐screw extruder, and then tests specimens for experimental characterizations were manufactured through injection molding. The tensile tests revealed that the inclusion of SH into PP decreased the load‐bearing capacity of the composites by around 20% and increased their impact resistance by over 200%, while reducing the ductility by about eight times. Moreover, magnesium hydroxide (Mg(OH)2) was incorporated into the composites as a flame retardant, and it has improved the stiffness and impact resistance of the composites. Besides, incorporation of SH and Mg(OH)2 elevated significantly the glass transition temperature of the composites. The use of Mg(OH)2 delayed 60% the flame retention of the composites observed from UL‐94 HB flammability testing. In summary, they could be suitable for components such as spare wheel wells, seat backs, trunk floor, the acoustic panel behind the door, and airbag housing.

Lumbar and neck injuries of occupants in different reclining postures

PurposeWith the increasing level of automation in automobiles, the advent of autonomous vehicles has reduced the tendency of drivers and passengers to focus on the task of driving. The increasing automation in automobiles reduced the drivers' and passengers' focus on driving, which allowed occupants to choose a more relaxed and comfortable sitting position. Meanwhile, the occupant's sitting position went from a frontal, upright position to a more relaxed and reclined one, which resulted in the existing restraint systems cannot to keep occupants safe and secure. This study aimed to determine the effects of different reclining states on occupants' lumbar and neck injuries. MethodsThis is an original research on the field of automotive safety engineering. Occupants in different initial sitting positions (25°, 35°, 45°, and 55°) were adapted to changes in seat back angle and restraint systems and placed in the same frontal impact environment. Neck injury indexes, lumbar axial compression force and acceleration, as well as occupant dynamic response during the impact, were compared in different sitting positions. The injury response and kinematic characteristics of occupants in different reclining positions were analyzed by the control variable method. ResultsAs the sitting angle increased, the occupant's head acceleration decreased, and the forward-lean angle decreased. Occupants in the standard sitting position had the greatest neck injury, with an Nij of 0.95, and were susceptible to abbreviated injury scale 2+ cervical medullary injuries. As the seatback angle increased, the geometric position of the lumbar spine tended to be horizontal, and the impact load transmitted greater forces to the lumbar spine. The occupant's lumbar injury was greatest in the lying position, with a peak axial compression force on the lumbar region of 5.5 KN, which was 2.3 KN greater than in the standard sitting position. ConclusionThe study of occupant lumbar and neck injuries based on different recline states can provide a theoretical basis for optimizing lumbar evaluation indexes, which is conducive to the understanding of the lumbar injury mechanism and the comprehensive consideration of occupant safety protection.

Dynamic characteristics of a compliant seat coupled with the human body and a manikin during the exposure to the whole-body vibration: Effect of the polyurethane foam, the track position, and the measurement location

Purpose Transmissibility is used to assess dynamic responses of the occupant-seat system, and most studies have exclusively assessed the transmissibility from the floor to the cushion or the backrest surface with the human body. Methods In this investigation, the vertical vibration transmitted from the floor to six specific locations both on the seat surface and the frame when the seat was fixed on three positions on the track was examined utilizing an SAE J826 manikin and 12 male adults (0.25 to 20 Hz) for a duration of 120 seconds at three vibration amplitudes. Results The transmissibility from the floor to the headrest frame, the cushion surface, the headrest surface, the seat back frame, and the seat back surface all exhibited a principal peak frequency within 4-5 Hz. With the exception of the cushion frame, the principal peak frequency and the peak transmissibility in transmissibilities to all positions decreased with increasing vibration amplitude, indicating the non-linearity within the occupant-seat system. It was also found modifying seat track positions minimally affected the seat transmissibility to either the surface or the frame of the seat. Conclusions Polyurethane foam amplified vibration at peak frequency, simultaneously enhancing static sitting comfort and reducing the vertical vibration transmission above peak frequency.

Influence of Driver's Seat Front and Back Position on Safe Driving Behaviour

Influence of Driver's Seat Front and Back Position on Safe Driving Behaviour

Variation of the secondary acoustic paths from loudspeakers at the seat shoulder in an automobile cabin

The secondary path is essential in the design of adaptive active noise control systems, and it varies with several factors in practical implementation. In this paper, the acoustic responses from secondary loudspeakers installed at the shoulder of the front passenger seat to the error microphones at the passenger's ears in an automobile cabin are measured, when the factors including the passenger movement, the seat posture and the passenger number change. The upper limit frequency where the phase variation is within 90 deg. compared to the reference position is analyzed. The results show that the state of both the passenger head and the seat back determines the lowest upper limit frequency among all the factors under investigation. If multiple factors change at the same time, the upper limit frequency will be further reduced.

Proposed Workstation Design in Laboratory for Musculoskeletal Disorder Complaints

Introduction:Laboratory is a means of improving the effectiveness of learning. The problem faced by laboratory staff in performing their work (analysis and experimentation) is fatigue caused by long work time with inappropriate sitting posture and position. The use of a wooden chair without a backrest and with a seat height that is too high or too low can cause musculoskeletal disorders (MSDs). This study aims to provide a workstation design suggestion with attention to ergonomics to reduce complaints of musculoskeletal disorders. Method: This descriptive research used an observational method. The population in this research consisted of 31 female students of a feed laboratory user, and the sample consisted of 16 respondents at the SIKIA Laboratory. Data collection for this study was conducted from July to September 2022. The independent variable in this study was the dimension of the workstation, and the dependent variable was musculoskeletal complaints. Result: Anthropometric measurements on laboratory assistants of the SIKIA Laboratory showed that the average popliteal height was 53.25 cm. Assessment on musculoskeletal disorder complaints shows that most complaints are found on “Pain in the back” with a score of 36. A new chair and table design is proposed, where the width of the seat back is 39.75 cm. Conclusion: A new workstation design is proposed that focuses on ergonomics to reduce the complaints of musculoskeletal disorders.

Research on seat active noise control of driver's cab ground platform based on far-point secondary sound sources

Driver's cab noise has an impact on the long-term driving environment and physical health of drivers. The locomotive driver's cab has significant low-frequency noise due to structure-borne sound, which is suitable for effective suppression by the active noise control system. However, on the one hand, the seat headrest system hinders the driver's movement space, on the one hand, the active noise control for space zones in the driver's cab has limited noise reduction effect due to the large control area. Therefore, a ground research test platform of driver's cab for active noise control was designed, and its structure and control method were introduced in this study. Based on the near-point seat active noise reduction control system, the coherence of the reference acoustic signal of the chair to the acoustic signal at the driver's left ear is very close with the one on the floor, and both of their active noise reduction in the full frequency band from 50 Hz to 5000 Hz are very close (about 4.5 dB (A)). In order to alleviate the interference of the headrest system installed with secondary sound sources on the driver's operating space, a far-point active noise reduction control system was proposed. The results showed that when two reference microphone signals from the seat back and floor position are used at the same time, the active noise reduction next to the driver's left ear in the full frequency band of 50 Hz to 5000 Hz is 4.0 dB(A), which is still significant. This provides a useful reference for the engineering application of active noise control systems in rail driver's cabs.

Tactile Displays: The Effects of Location and Intensity on Automated Vehicle Takeover Performance

This study investigated the effects of tactile display location and intensity on automated vehicle takeover performance. Twenty participants completed simulated driving tasks in a Level 3 automated vehicle and responded to takeover requests presented at different locations (seat back, seat pan, seat belt, and wrist) with different intensity levels. Results showed that higher intensity tactile displays were associated with faster takeover times, and placing the display on the wrist was correlated with shorter takeover times compared to the seat pan in lower intensity. However, there were no significant effects on maximum resulting jerk. These findings suggest that incorporating tactile displays in automated vehicles as takeover requests is promising, particularly when placed on the wrist and presented at higher intensities. This research contributes to the development of human-machine interfaces that can better assist drivers during takeovers and improve the safety of automated vehicles.

To Inform or to Instruct? An Evaluation of Meaningful Vibrotactile Patterns to Support Automated Vehicle Takeover Performance

Automated vehicles may occasionally require drivers to take over. The complexity of the takeover process warrants the design of effective human–machine interfaces that assist drivers in regaining control, especially when the visual and auditory sensory modalities are occupied. Vibrotactile displays, which can represent information about the status, direction, and position of driving environment elements, have been suggested as one promising approach, but their effectiveness to aid in takeover transitions has not been fully evaluated. This study investigated the effects of meaningful tactile signal patterns, used as takeover requests, on automated vehicle takeover performance. Forty participants rode in a simulated SAE Level 3 automated vehicle and completed a series of takeover tasks with two tactile pattern formats, i.e., informative (which displayed status information of surrounding vehicles) and instructional (that displayed the appropriate takeover maneuver), and three in-vehicle locations (seat back, seat pan, and a seat back and seat pan combination). Takeover response options included lane changes only or brake applications followed by changing lanes, depending on the locations of surrounding vehicles. Results indicate that only meaningful instructional tactile signals, in either the seat back or seat pan, were associated with worse takeover response time and maximum resulting acceleration compared to signals without any patterns. Additionally, tactile information presented on the seat back was perceived as the most useful and satisfying. Findings from this study can inform the development of next-generation human–machine interfaces that utilize tactile stimulation in a wide range of environments with automation.

Effect of seat back angle on preferred seat pan inclination for the development of highly automated vehicles

Recent studies on occupants’ safety in reclined positions suggest that a more inclined seat pan could be needed to reduce the occurrence of submarining. This study aimed to investigate whether a more inclined seat pan would also be comfortable for occupants. Eighteen volunteers participated in the experiment. They were asked to self-select seat pan inclination for seat back angles from 20 to 60 degrees using a reconfigurable experimental seat from two initial seat pan angles (10 and 40 degrees from the horizontal). On average, preferred seat pan angle varied from 11.3(±2.1, standard deviation) to 29.9(±6.8), 12.5(±3.8) to 37.4(±3.7), and 12.8(±4.8) to 38.6(±2.7) degrees for seat pan angles of 20, 40, and 60 degrees respectively. The shear force analysis suggests that the seat pan inclination might be self-selected to reduce the forward shear, while a high inclination angle with a noticeable backward shear was also preferred. Practitioner summary: Preferred range of seat pan inclination for different seat back angles studied for the development of highly automated vehicles. The present work provides quantitative guidelines for specifying comfortable seating in a reclined position.

Lightweight Design of Differential Thickness-Carbon Fiber Reinforced Plastic Car Seat Backrest

To realize the light weight of the seat back of a new energy vehicle, this study uses the idea of differential thickness to remove the reinforcing ribs of the seat back while meeting the requirements of performance and assembly of the carbon fiber seat back and then carries out the structural design and layer optimization of the seat back to minimize the overall quality of the seat back. The finite element model of the car seat is established by finite element analysis software, and the definition visualization of carbon fiber composite is realized in Hypermesh software. Finally, the light effect of the carbon fiber backrest of automobile seats is 22.1%, which meets the design purpose and requirement of the differential thickness of the backrest.

A MIMO system for the replication of accelerations excited in a vehicle by single obstacle crossings at comfort-relevant excitation points in a comfort simulator

This paper presents the replication of accelerations in a vehicle excited from single obstacle crossings. The accelerations should be replicated at multiple comfort-relevant excitation points in a comfort-simulator. For the vertical accelerations at the seat rails and the foot rests, research on the positions and the number of shakers is conducted. The implementation of an electrodynamic shaker for each controlled measurement point turns out to be mandatory. By positioning them at the left and right seat rails, errors can be minimized due to similarities in the transmission behavior. The longitudinal excitations of the seat back by means of shakers are performed very precisely. The direct coupling by a construction on the headrest allows fast exchange of the vehicle seats. The combination of all acceleration replications simultaneously can be performed satisfactorily comparing them with in-vehicle field measurements. The noise-based excitation signal for system identification turns out to be a significant parameter.

Four Elegies

Four Elegies

MINIMIZING THE RISK FACTORS FOR LOW BACK PAIN IN THE CREATIVE INDUSTRY WORKERS

Low back pain (LBP) felt in the anatomical area of ??a person's body is affected by a load or pressure outside the tolerance limit, with various variations in the length of time the pain complaint process occurs. This pain is felt in the lumbar or lumbo-sacral area. Workers in the batik industry may be at risk of LBP caused by work activities, such as bending, repetitive or monotonous movements, using work equipment and a non-ergonomic work environment. This study aims to minimize the risk factors for LBP in batik creative industry workers. The population of this study were all batik artisans in the written batik industry in Wukirsari Village, Imogiri District, Bantul Regency, Yogyakarta Special Region, totaling 1,021 people. The sample of this study was obtained by random sampling, to determine the sample using a lottery number and the name of the batik maker, totaling 60 batik people. The inclusion criteria for the sample of this study included female gender, writing batik work, working sitting using a chair. The sample consisted of a treatment group and a control group, each consisting of 30 batik makers, hereinafter referred to as respondents. The research instruments include: meter, microthoice, scales, chair, batik hurdle, and NBM questionnaire. Ergonomic work chair design for batik size: height of seat holder = 30 cm; length of seat holder = 40 cm; seat width = 37 cm; high back of chair = 43 cm; seat back width = 37 cm. Modification of batik gawangan is to redesign batik gawangan, material from bamboo diameter of about 3 cm, with size: height = 88 cm, width = 158 cm, 4-legged pieces, equipped with 3 watt LED lights. The results of the NBM in the treatment group decreased skeletal muscle complaints into criteria: low 96.7% and moderate 3.3%. The control group had skeletal muscle disorders criteria: low 23.3%, moderate 46.7%, high 20% and very high 10%. While the results of the t-test from the NBM data each of the 30 respondents between the treatment group and the control group, the value of p = 0.000 means that there are significant differences between respondents who use chairs and ergonomic modification modifications with respondents who use dingklik and gawangan which is old. The conclusion is that the use of chairs and modifications of the ergonomic batik wrestling can minimize the risk factors for LBP in the workers of the written batik creative industry

Fatigue behavior of hybrid eco-composites: A review

Multifunctionality of composites has gained popularity, primarily through the hybridization of polymer composites for augmented performance. In this case, hybridization is ensured by adding fibrous reinforcement of different materials. There are a multitude of characteristics which can be enhanced due to hybridization. The synthetic reinforcements respond to uncontrolled carbon footprints, so we cannot claim them as sustainable. Hence, scientists have been discovering new solutions in sustainable eco-composites (with natural reinforcements) to tackle the environmental challenge. It is reported that albeit the natural fibres are eco-friendly, but they often lack in desired properties and hence find difficulty to enter the market. To achieve desired properties, several limitations of natural fibre, such as hydrophilic qualities, can be addressed by different surface alterations and chemical treatment procedures. Post the fourth industrial revolution, the rising concern about environmental issues has led an increased interest in natural fibre hybrid composites (also called as hybrid eco-composites). Such composites are composed of eco-friendly fibres or a combination of synthetic and natural fibres as a reinforcing material which makes it capable for multifunctional applications. Natural fiber reinforced composites have a great potential of cost per unit weight reduction and renewability over applications such as door panel, seat backs, dashboard, noise insulation panel, railing, bridge, and roof tiles. The prior art reveals that these composites have low fatigue strength which limits itself in structural application in comparison to its competitors, the synthetic composites. This means hybridization could result in synergy of advantages of each of the constituents leading to high fatigue strength, better load carrying, eco-friendly, and a low-cost structure. This review provides an overall insight on various hybrid eco-composites including their mechanical properties, fatigue behavior and its applications.

Effects of seat back height and posture on 3D vibration transmission to pelvis, trunk and head

Vibration transmission is essential in the design of comfortable vehicle seats but knowledge is lacking on 3D trunk and head motion and the role of seat back and posture. We hypothesized that head motion is reduced when participants’ upper back is unsupported, as this stimulates active postural control. We developed an experimental methodology to evaluate 3D vibration transmission from compliant seats to the human body. Wide-band (0.1–12 Hz) motion stimuli were applied in fore-aft, lateral and vertical direction to evaluate the translational and rotational body response in pelvis, trunk and head. A standard car seat was equipped with a configurable and compliant back support to test 3 support heights and 3 sitting postures (erect, slouched, and preferred) where we also tested head down looking at a smartphone.Seat back support height and sitting posture substantially affected vibration transmission and affected low frequency responses in particular for body segment rotation. According to our hypothesis a low support height proved beneficial in reducing head motion. Relevance to industryOur methodology effectively evaluates 3D wide-band vibration transmission from compliant seats to the human body. The lowest back support height reduced head motion but was perceived as least comfortable. This calls for seat designs which support but do not so much constrain the upper back. The head down posture enlarged head motion, pleading for computer system integration allowing heads up postures in future automated cars. The biomechanical data will serve to validate human models supporting the design of comfortable (automated) vehicles.