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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Effect of backrest on head-cervical spine biodynamics in seated human: A finite element study</title>
      <link>https://trid.trb.org/View/2691773</link>
      <description><![CDATA[This paper studied the effect of backrest support (no backrest support (NBS), ergonomic backrest support (EBS) and non-ergonomic backrest support (N-EBS)) on the biodynamics of the head-cervical spine. Using a previously developed finite element model of a 3D body-seat system, modal and random response analyses were done under vertical white noise excitation (between 0 and 20 Hz at 1 m/s2 r.m.s). The results showed that modal frequencies at 5.45 and 7.33 Hz (EBS), 4.23 and 6.05 Hz (N-EBS) and 4.14 and 4.84 Hz (NBS) significantly influenced the vertical vibration of the seated human body. Compared to the NBS model, the peak frequencies of the head and neck response increased by 33% and 55% in the N-EBS and EBS models, respectively, and peak amplitudes at the front of the head increased by 25% (N-EBS) and 45% (EBS), while those at the back of the head-cervical spine decreased consistently. The response of the different positions of the head varied most significantly in the EBS model, with peak frequency and difference of 53% and 30%, respectively. All back supports showed the highest stress at C5–C6 of the cervical disc, with a peak between 1 and 2 Hz. Notably, EBS reduced the vertical cervical response but increased the anterior-posterior response. This paper provided a new idea for studying the biodynamics of the head-cervical spine as well as theoretical and applied guide for the safe and comfortable design of seats and the reduction of cervical spine injuries.]]></description>
      <pubDate>Thu, 16 Apr 2026 09:25:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2691773</guid>
    </item>
    <item>
      <title>Human back contour modeling for backrest design in future vehicles</title>
      <link>https://trid.trb.org/View/2636352</link>
      <description><![CDATA[As automated vehicles evolve, seating designs must accommodate a wider range of postures, particularly for non-driving-related activities such as relaxing and sleeping. This study aims to model human back shapes in seated and reclined positions to improve ergonomic seat designs. Human back contour data were collected from 36 participants using a custom measurement device in two setups: a 25° backrest angle and a seat pan angle of 15°, simulating a driving posture, and a 50° backrest angle with the same seat pan angle, representing a reclined posture. Statistical Shape Models (SSMs) were developed to analyze the variability of back contours. The 25° setup exhibited a flatter spinal curve and higher compactness, capturing 79.7 % of the variance with the first principal component (PC1), compared to 74.6 % in the 50° setup. The combined setup balanced these differences, providing a comprehensive model for diverse postures. Overall, PC1, PC2, and PC3 together captured more than 96 % of total contour variance, indicating that variations in back height, neck bending, and lumbar prominence constitute the dominant sources of geometric diversity. These findings offer actionable dimensions for designing ergonomic backrests that support diverse users and postures. Future research should investigate whether implementing these guidelines enhances comfort and should include more diverse populations and a broader range of postures.]]></description>
      <pubDate>Thu, 05 Feb 2026 09:16:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2636352</guid>
    </item>
    <item>
      <title>Multi-objective optimization design of automobile seat backrest considering coupling effect</title>
      <link>https://trid.trb.org/View/2608022</link>
      <description><![CDATA[To investigate the impact of the coupling effects of carbon fiber reinforced polymer in the seat back layer on the performance of car seats, this paper presents a comprehensive optimization design method for composite materials. In detail, the finite element models firstly established and validated through five typical working conditions of automotive seats based on experimental data. Then, the optimized variables are divided and determined through backrest stress nephograms for each working conditions of the automotive seats, in which the various perspective are taken into account, such as the total mass of seat backrest, safety performance, and comfort index. Subsequently, an optimization strategy for unequal thickness layers lay-up design is constructed, which combines strength factors, optimal Latin hypercube sampling, best-worst method, gray relational analysis, and Visekriterijumsko KOmpromisno Rangiranje method for the optimal design of the automotive CFRP seat backrest. Additionally, the impact of layer coupling effects on different performance indices of the seat is examined through simulating and analyzing the seat backrest with various layer coupling types, while incorporating the classical laminate theory. The study reveals that by minimizing the laminate coupling effect, the comfort of the seat can be enhanced. Finally, a comprehensive comparative analysis of the optimal trade-off solution is carried out in terms of optimization strategies. The results show that ensuring the safety performance, the total mass of the seat backrest decreased by 21.3%, as a result of the optimization strategy proposed in this paper, and the comfort performance is also improved to some extent. Therefore, the multi-objective optimization strategy proposed in this paper performs well in terms of effectiveness and provides a reliable reference for related composite material multi-objective optimization.]]></description>
      <pubDate>Tue, 16 Dec 2025 09:29:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608022</guid>
    </item>
    <item>
      <title>Effects of seatback angles on passenger kinematics among the longitudinal braking scenario</title>
      <link>https://trid.trb.org/View/2606426</link>
      <description><![CDATA[With the development of autonomous vehicles and zero gravity seats, the passengers are more likely to sit in their preferred postures, such as the high reclined positions. This study aims to analyse the passenger kinematics under different seatback angles by volunteer experiments, which is beneficial for future smart restraint system development. For this study, four volunteers were selected to participate in the longitudinal braking experiments from 80 km/h to 0 km/h, and each volunteer repeated 3 times. Among the tests, three seatback angles (25°, 45°, and 60° from the vertical) were introduced, while the seat pan angles were the same. The seatbelt forces, as well as the volunteers’ motions were recorded among the experiments. The experimental results indicated that both head displacement and the first thoracic vertebrae (T1) displacement increased gradually with the increase of the seatback angle. The average T1 displacements for four volunteers under 25° seatback angle were between 180.2 mm to 245.5 mm, while the T1 displacements for 45° seatback angle and 60° seatback angle were between 291.4 mm to 374.3 and 366.2 mm to 444.5 mm respectively. Both shoulder belt force and lap belt force increased with the increase of seatback angle, except for the 60° case of No.1 volunteer, which might due to the muscle activation level difference. In this study, there was no significant correlation between the seatback inclination angle and the amount of seat belt outlet amount. The study is beneficial for active human model validation and future smart restraint system development.]]></description>
      <pubDate>Mon, 17 Nov 2025 09:00:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2606426</guid>
    </item>
    <item>
      <title>Nonlinear Impact of Seatback Recline Angle and Crash Pulse Magnitude on Head Injury Risk During Rear-End Impacts</title>
      <link>https://trid.trb.org/View/2611428</link>
      <description><![CDATA[Out-of-position (OOP) testing is increasingly important due to the development of autonomous vehicles, innovative car seat designs, and the need to verify safety in various seating configurations. This study analyzes the impact of seatback recline angle and crash pulse magnitude on head injury risk during rear-end impacts, focusing on the Head Injury Criterion (HIC). Using a sled system and a Hybrid III 50th-percentile dummy, 12 crash scenarios were examined with crash pulses of 10 g, 15 g, and 20 g and seatback recline angles of 21degree, 25degree, 38degree, and 55degree. The results showed that increasing the seatback recline angle reduces peak head accelerations but extends their duration, which, based on the Wayne State Tolerance Curve (WSTC), may increase injury risk. The HIC increased nonlinearly with higher crash pulses, especially in upright positions. The study proposes the Pelvis-to-Headrest Transmission Effect as a newly observed dynamic mechanism affecting head and neck injury risk. Findings suggest that a more reclined posture may enhance biomechanical safety in rear-end collisions, although the effect is complex and depends on multiple factors. Video analysis and Z-axis acceleration data confirmed that certain reclined configurations can increase compressive forces on the cervical spine, highlighting the need for comprehensive safety assessment.]]></description>
      <pubDate>Thu, 23 Oct 2025 09:22:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2611428</guid>
    </item>
    <item>
      <title>TMA Truck Safety</title>
      <link>https://trid.trb.org/View/2577119</link>
      <description><![CDATA[This study evaluates the effectiveness of in-vehicle safety countermeasures in reducing injury risk for TMA (Truck-Mounted Attenuator) truck occupants during collisions. With increasing incidents involving TMAs in work zones, understanding the protective impact of advanced safety features has become crucial. A review of historical TMA crash reports revealed that rear-end collisions are the primary issue, with whiplash injuries being the most common type of injury among drivers. Current in-vehicle safety countermeasures were examined, including active headrests, reactive seatbacks, and anti-whiplash systems, which were tested across six simulated collision scenarios incorporating varying vehicle weights, speeds, and impact angles. Using a biomechanical simulation model and telematic data, results indicated that active headrests, particularly with 40 mm travel level, consistently reduced injury criteria values (NIC, Nij, Nkm), effectively lowering head and neck injury risks in both straight and angled collisions. In contrast, the reactive seatback and anti-whiplash systems demonstrated mixed efficacy, performing well in low-impact conditions but poorly in high-impact scenarios. Limited high-impact telematic data, particularly with 80,000-pound vehicles, highlight the need for further validation for high-impact collision scenarios. Findings suggest that integrating advanced head restraint systems could significantly enhance TMA truck driver safety.]]></description>
      <pubDate>Mon, 18 Aug 2025 08:50:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2577119</guid>
    </item>
    <item>
      <title>Effects of dual-message tactile sliding takeover requests on takeover performance in an automated driving system</title>
      <link>https://trid.trb.org/View/2540066</link>
      <description><![CDATA[The present study aimed to explore the effects of various tactile takeover requests (TORs) (i.e., tactile sliding TOR and traditional vibration TOR) on the takeover performance in an automated driving system. A tactile sliding motor device was developed to signal the sliding TOR on the seatback of a driving simulator. Twenty-five young drivers were recruited as participants. Four types of TOR patterns were adopted in the study: ipsilateral motor rotation (IR), contralateral motor rotation (CR), ipsilateral and contralateral motor rotation (ICR), and ipsilateral motor vibration (IV). The participants were required to sit on the seat and underwent the automated driving in a low- or high-complexity scenario, then one of the four types of TORs was triggered randomly. The participants were asked to make a lane change using the steering wheel as soon as possible. Objective measures and subjective evaluations were used to assess the takeover performance. Results showed that the participants exhibited a shorter steering response time and lane change time under the three tactile sliding TORs (compared to the traditional vibration TOR). In the high-complexity scenarios and low-complexity scenarios conditions, different result patterns appeared regarding the maximum lateral acceleration and situational awareness. The authors conclude that their findings suggested that the tactile sliding motor is a promising way to signal a TOR in an automated driving system.]]></description>
      <pubDate>Mon, 19 May 2025 09:11:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2540066</guid>
    </item>
    <item>
      <title>A Reconfigurable Backrest Surface for Investigating Preferred Seat Configurations</title>
      <link>https://trid.trb.org/View/2539624</link>
      <description><![CDATA[A reconfigurable experimental seat is useful for seating comfort research and allows researchers to investigate the effects of seat parameters and to propose quantitative guidelines for improving seat comfort. Since 2017, Gustave Eiffel University has such an experimental seat which allows us to carry out parametric studies on the geometric dimensions of a seat and to understand the role of the contact force, particularly that in shear force. Equipped with force and positioning sensors, all contact forces and seat position can be measured. More specifically, it is equipped on the seat with a matrix of 52 cylinders, each adjustable in height and each equipped with a three-axis force sensor. These cylinders make it possible to vary the contact surface of seat pan and measure the distribution of contact forces. More recently, a new system with a matrix of 263 hydraulic cylinders was designed and manufactured to better study the comfort of the backrest in replacement of the three-support backrest. As for the seat pan cylinders, each cylinder for the backrest is also equipped with a force sensor and adjustable in position using a pumping system. The device has two control interfaces, one for the experimenter and the other for the participants in an experiment. The authors can easily define the same test configuration for all participants. A participant has the possibility of easily modifying the seat geometry using a tablet via an interactive interface according to their preference. The purpose of this paper will be to present the technical specifications of the experimental seat with the new backrest system and its evaluation. This experimental seat could be pivotal especially for improving backrest comfort.]]></description>
      <pubDate>Fri, 16 May 2025 09:33:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2539624</guid>
    </item>
    <item>
      <title>The effect of reclined seat-back angles on the LODC with and without a belt-positioning booster during far-side lateral-oblique impacts</title>
      <link>https://trid.trb.org/View/2452806</link>
      <description><![CDATA[ObjectiveIn frontal crashes belt-positioning boosters (BPB) may prevent submarining when the seatback is reclined. It is unclear if the BPB can also mitigate injuries in far-side lateral-oblique crashes in reclined conditions, where current restraints are less effective in reducing lateral excursion. This study aimed to understand reclined child injury risk during lateral-oblique impacts, with and without a booster seat, by using the Large Omni-Directional Child (LODC) test device.MethodsThe LODC was tested in nine lateral-oblique impact (80° from frontal) sled tests (target 31.3?km/h, duration 58?ms maximum, peak acceleration 21?g). Three seatback angles (25°, 45°, and 60°) with and without the BPB were compared on a production passenger seat with an integrated seatbelt. The LODC moved toward the buckle side during the far-side lateral-oblique impact. Abdominal pressure (left and right), seatbelt loads, anterior superioriliac spine (ASIS) forces, and pelvis lateral rotation were examined. The LODC head and knee excursions were extracted from a 3D-motion capture system.ResultsIn the reclined noBPB condition, peak abdominal pressures on the buckle side reached up to 186?kPa and the ASIS forces demonstrated an early (~ 50?ms) peak and a subsequent drop in the reclined noBPB conditions, suggesting that the belt slid into the abdomen.With the BPB, peak pelvis lateral rotation was greater than in the noBPB conditions but decreased with increasing reclined seatback angles (BPB: 31° to 36.5° vs no-BPB: -5° to -4.6°). Peak lap belt forces were greater in the reclined noBPB conditions (4.8-4.9?kN) compared to all conditions with the BPB (2.9-3.2?kN).The greatest lateral head excursion was observed in the BPB 25° condition (895?mm) and the lowest in the noBPB 45° condition (748?mm).ConclusionsThe BPB may prevent the lap belt intrusion into the abdomen in reclined configurations in far side lateral-oblique impacts. The greater pelvis lateral rotation and head displacement with the BPB may lead to contact with other rear-seated occupants and/or vehicle structures, although motion decreased with the BPB as the reclined seatback angle increased. This suggests that reclined seats may help reduce BPB-seated children’s lateral excursion in far-side lateral-oblique impacts.]]></description>
      <pubDate>Mon, 27 Jan 2025 15:11:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2452806</guid>
    </item>
    <item>
      <title>Effects of seatback angle, seat rotation, and impact speed on injury risk of occupants in highly automated vehicles in frontal crashes</title>
      <link>https://trid.trb.org/View/2452796</link>
      <description><![CDATA[ObjectiveThe objective of this study is to examine the effects of seatback angle, seat rotation, and impact speed on occupant kinematics and injury risk in highly automated vehicles.MethodsThe study utilized the Global Human Body Models Consortium midsize male (M50-OS+B) simplified occupant model in a simplified vehicle model (SVM) to simulate frontal crashes. The M50-OS+B model was gravity-settled and belted into the driver and left rear passenger seat. To investigate the effects of seatback angle, seat rotation, and impact speed on occupant kinematics and injury risk in frontal crashes, a design of experiments (DOE) was conducted. The DOE incorporated four seatback angles (13°, 23°, 45°, and 57.5° about vertical), four seat rotation angles (0°, 25°, 45°, and 90°), three impact speeds (25, 35, and 45 kph), and four frontal crash type configurations. All four seatback angles were used with 0° seat rotation, whereas 13° seatback angle was used with the remaining seat rotation configurations because of cabin fit considerations. Injury risks were estimated for the head, neck, shoulder, thorax, pelvis, and lower extremities for both occupants for each simulation (n=588).ResultsStatistically significant differences between all the groups within each independent variable category were observed based on the analysis of variance. HIC-based head injury risk and chest injury risk decreased and femur force for the driver and tibia force for the passenger increased with an increase in seatback angles. The head injury risk increased with seat rotation. All the injury risks increased with an increase in impact speed. The driver airbag was able to safeguard the driver from head injuries for all seat rotations except at 90° of seat rotation.ConclusionThis is the first vehicle modeling study that collectively looked at the effects of seatback angle, seat rotation, and impact speed along with the interaction of occupants on the risk of injury in frontal crashes. The rear passenger experienced higher seatbelt loads than the driver. More reclined seats decreased head and chest injury risk, but increased driver femur injury risk and rear passenger tibia injury risk. Results underscore the necessity for additional anti-submarining mechanisms and driver airbag designs adapted for the anticipated occupant positions.]]></description>
      <pubDate>Mon, 27 Jan 2025 15:11:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2452796</guid>
    </item>
    <item>
      <title>Evaluation of Fillet Welds Properties Performed by Cold Metal Transfer Robotic Metal Active Gas Welding Technology</title>
      <link>https://trid.trb.org/View/2475204</link>
      <description><![CDATA[The article is the result of research evaluating the quality of fillet welds used in the production of rear seat backrests for passenger cars and manufactured robotically by Cold Metal Transfer (CMT) robotic Metal Active Gas (MAG) welding. When robotizing the process, parameters such as the speed of the process itself, accuracy and quality of the welded joints are important. Dual-phase ferritic-martensitic steel HCX 590X was used for the experiment and four weld nodes were evaluated. The quality of welded joints was evaluated by visual and capil-lary methods. Based on the metallographic analysis, the weld depth of the weld root was evaluated. The measured values were subsequently processed by statistical method ANalysis Of Variance (ANOVA). The research confirmed that the final quality of the welds depends on the depth of the weld root weld into the Base Material (BM). This parameter has the greatest effect on the welds made and results in the entire product being taken out of service.]]></description>
      <pubDate>Fri, 13 Dec 2024 17:02:43 GMT</pubDate>
      <guid>https://trid.trb.org/View/2475204</guid>
    </item>
    <item>
      <title>Effect of seat back angle on preferred seat pan inclination for the development of highly automated vehicles</title>
      <link>https://trid.trb.org/View/2367089</link>
      <description><![CDATA[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.]]></description>
      <pubDate>Tue, 30 Apr 2024 11:23:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/2367089</guid>
    </item>
    <item>
      <title>Development of a New PVC-Gel Actuator for Implementing Emotional Vibration</title>
      <link>https://trid.trb.org/View/2155529</link>
      <description><![CDATA[Electro-hydraulic actuators, a type of soft actuators, can provide soft-touch vibrations due to their structural characteristics, but some problems need to be improved to apply them to vehicles. That is, it is necessary to increase excitation force, expand frequency band, lower driving voltage, and increase durability. This research aims to design a new type based on electro-hydraulic actuator and improve problems with its performance to develop a product that generates emotional vibration in vehicles. First, a new mechanism and design of an electro-hydraulic actuator called a PVC-gel film actuator are proposed. This actuator uses PVC-gel as a film which covers a dielectric liquid and uses carbon nanotube as a cathode material. In addition, a method of manufacturing an actuator with improved performance has been proposed by creating and testing prototypes with different sizes and material properties. It has been verified that the proposed actuator improves excitation force, frequency band, driving voltage, and durability compared to the existing actuator. Next, as a result of investigating the object that this actuator can exert the most effect on a vehicle based on body sensitivity, a device has been developed that built into a neck pillow in front of the vehicle seat and linked to the music played on the vehicle to generate a comfortable vibration in the neck. In addition, four vibration scenarios have been constructed to generate vibrations according to various genres of music. Finally, as a result of testing on a vehicle with a large number of people, it has been verified that the vibration generating device developed in this study can provide a new and emotional vibration experience for users.]]></description>
      <pubDate>Thu, 27 Apr 2023 17:02:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2155529</guid>
    </item>
    <item>
      <title>Motion sequence criteria for favorable occupant kinematics in rear impacts</title>
      <link>https://trid.trb.org/View/2140209</link>
      <description><![CDATA[Rear-impact restraint guidelines have not developed to the same degree as for frontal crashes. This study provides criteria for favorable occupant kinematics in rear impacts. Rear criteria were developed as an extension of Adomeit and Heger (1975) and Adomeit (1977) motion sequence criteria (MSC) for favorable occupant kinematics in frontal crashes. In this study, occupant kinematics in rear sled tests were studied to develop motion sequence criteria for favorable and unfavorable occupant kinematics in rear impacts with containment of the hip on the seat and no ramping up the seatback. Rear MSC limit the angle of the torso (α) rearward of vertical to less than the critical angle (αc) for ramping up the seatback and H-pt displacement rearward and downward, so zHpt < zHpt0, where zHpt0 is the initial height of the H-pt. The lateral displacement of the occupant is limited to less than the critical lateral displacement yT1c, where the head becomes unsupported by the head restraint or the chest by the seatback. The rear MSC contain the pelvis on the seat and provide uniform support of the torso, head and neck. Most front seats in production provide reasonably favorable occupant kinematics in rear impacts up to 40 km/h (25 mph) delta V with the 50th Hybrid III. Kinematics become unfavorable in testing at higher severities and with heavier occupants. The amount of energy that the seat needs to transfer to the occupant in a rear impact depends on the delta V (ΔV or change in velocity) of the vehicle and the mass of the occupant (m) among other variables. The seat provides an interface with the occupant and transfers energy (E), which can be approximated by E = ½*0.7*m(ΔV)2 using 70% of the occupant mass (m) and delta V. Rear MSC provide performance guidelines to advance seat designs with favorable occupant kinematics at higher energy transfer levels in rear impacts. Sled testing at 40 km/h (25 mph) involves an energy transfer of 3,421 J with the 50th Hybrid III generally gives favorable kinematics. A 56.3 km/h (35 mph) test involves 6,704 J, double the energy transfer and often unfavorable kinematics. A target energy needs to be set, and there are practical limits because the energy transfer is 12,858 J with a 150 kg (330 lb) occupant in a 56.3 km/h (35 mph) delta V rear crash. Rear motion sequence criteria (MSC) define favorable kinematics in rear impacts. MSC complement the assessment of biomechanical responses in sled and crash testing to ensure an overall evaluation of occupant restraint in rear impacts.]]></description>
      <pubDate>Mon, 17 Apr 2023 09:01:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2140209</guid>
    </item>
    <item>
      <title>Quasi-static methods to evaluate seat strength in rear impacts</title>
      <link>https://trid.trb.org/View/2140208</link>
      <description><![CDATA[Various methods have been used in the past 50 years to apply Quasi-static load to a seat in the rear direction and measure seat performance in rear impacts. This study compared five of the most-common test procedures to evaluate seats. In addition, occupant mass and center of gravity are discussed as important characteristics of rear loading of seats. Data was collected and analyzed from five different seat pull tests, including FMVSS 207, modified FMVSS 207, QST, body block and FRED II. Test data included peak force, moment and angle at peak moment. Occupant loading height of was determined using body segment weights and position in the forward (x) and vertical (z) directions based on anthropometry data. Some of the inherent differences in the tests are shown by comparing data with the same seat structure. The QST and FRED II use a lower height of loading than FMVSS 207. The QST and FRED II peak moment and force did not coincide with the same seatback angle as in FMVSS 207 and body block testing. Center of gravity height varies depending on whether the whole body or only the upper torso is considered. For the 50th male, it is 171.5 mm (6.8”) with the whole body and 246.7 mm (9.7”) with the upper torso. Results from different tests cannot be readily compared because of different loading conditions, including body shape and height of load about the H-point, which can cause the seat structure to respond differently.]]></description>
      <pubDate>Mon, 17 Apr 2023 09:01:46 GMT</pubDate>
      <guid>https://trid.trb.org/View/2140208</guid>
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