Seat Belt Anchorage Research Articles

Trend analysis of rear child occupants’ injury influenced by protection system parameters

As road traffic accidents are the leading cause of child injuries and deaths, the most common frontal impact is offset impact. Taking into consideration the lack of research on rear seat child occupants’ safety in road accidents, this study focuses on 10-year-old child occupants seated in the rear and establishes an analytical model of child injury during frontal offset impact, which is validated using test data from a real car impact of the same model. The study then examines the effects of restraint system parameters, including seat belt force-limited level, seat belt anchorage position, and seat cushion stiffness, on head, neck, and chest-abdomen injury response in the rear seat child occupants. The study found that reducing the seat belt force-limited level appropriately resulted in a significant decrease in the child occupant’s head resultant acceleration by 39.9% and the upper neck force by 53.2%. Meanwhile, increasing the seat cushion stiffness was found to reduce the child occupant’s head resultant acceleration by 18.8%, the upper neck force by 31%, and the abdominal pressure by 34.4%. This study provides a reference for the protection of rear seat child occupants.

Improving protection system for wheelchair-seated occupants in vehicle side impacts

Objective: Previous research on occupant protection systems for wheelchair-seated occupants focused on frontal impacts, while similar studies on side impacts are very limited. The objective of this study was to identify the major injury concerns for wheelchair-seated occupants in side impacts and develop restraint systems to mitigate such injury concerns. Methods: Seven sled tests in side impact conditions were first conducted at 30 km/h with a 24 g peak deceleration. An ES2-RE ATD and surrogate wheelchair base (SWCB) were used in all tests, which varied armrest design, width of the SWCB, and wheelchair tiedown conditions. These sled tests set up the baseline performance and provided validation data for computational models. A set of validated MADYMO models were then used to investigate the safety concerns and potential restraint solutions for wheelchair-seated occupants in side impacts. Simulations covered nearside and farside impacts, inboard or outboard D-ring locations, varied wheelchair locations relative to the side door, varied seatbelt anchorage locations, and a few Center Airbag To Contain Humans (CATCH) designs. Finally, another set of sled tests were conducted to demonstrate the effectiveness of varied CATCH designs for protecting wheelchair-seated occupants in farside impacts. Results: Simulations suggested that wheelchair-seated occupants might fall from the wheelchair in farside impacts, while in nearside impacts the seatbelt and curtain airbag can provide reasonable protection to occupants using wheelchairs. The CATCH design, a curtain airbag mounted to the roof centerline with tethers attached outboard of the wheelchair station, was effective at preventing the ATD from falling off the wheelchair. Results from sled tests to iterate CATCH parameters confirmed that the concept was effective at retaining occupants seated in wheelchairs under farside impact loading. Conclusions: This study is the first to investigate wheelchair-seated occupant protection in both nearside and farside impacts. The injury concerns identified in farside impacts and the CATCH design can potentially help improve the protection of wheelchair-seated occupants in side impacts in the future. The CATCH design has potential to improve farside protection for occupants in traditional seating.

경량설계를 위한 고강도강 적용 Seat 보강재 차체 부품의 Seat Belt Anchorage 해석

일반강보다 더 높은 강도특성을 갖는 고강도강은 가격경쟁력 측면에서 비철금속이나 샌드위치 복합소재보다 경량재료로 각광받고 있다. 또한, 가공의 용이성 측면에서도 고강도강은 경량재료로 떠오르고 있다. 그러므로 본 연구에서는 부품의 두께를 줄여 경량화를 이루는 데 600 MPa 이상의 인장강도를 갖는 고강도강을 자동차 시트 보강재료에 적용하는 것을 목표로 하였다. 이를 위하여, FMVSS 210 북미법규를 만족하는 해석방법을 제시하였으며 해석 결과를 나타내었다. 자동차 시트 보강재료의 상부(upper) 판재에 적용된 SPFC340 소재와 하부(lower) 판재에 적용된 SCP1 소재를 상대적으로 성형성을 개선하여 개발된 고강도강인 TR590 및 DP590 소재로 대체하여 개발하였다. 이를 통해 각 부품의 충돌 안전성에 대한 경량화 가능성을 연구하였다. 연구 결과, 1.0 t의 고장력강을 적용하게 되면 앞 상부 시트벨트 보강재는 16.6%, 앞 하부 시트벨트 보강재는 28.6%의 경량화가 가능함을 확인하였다.

경량설계를 위한 고강도강 적용 A, B-Pillar 차체 부품의 Seat Belt Anchorage 해석

최근 개발되고 있는 고강도강은 가격경쟁력 측면에서 비철금속이나 샌드위치 복합소재보다 경량재료로 연구되고 있다. 그러므로 본 연구에서는 부품의 두께를 줄여 경량화를 이루는데 600 MPa 이상의 인장강도를 갖는 고강도강을 자동차 A-pillar 및 B-pillar에 적용하는 것을 목표로 하였다. 이를 위하여, FMVSS 210 북미 법규를 만족하는 해석을 수행하였다. 자동차 차체부품인 A-pillar 판재에는 기존소재인 SPFC440 소재를 B-pillar 판재에는 SPFC340 소재가 적용되어 있었으며 이를, 상대적으로 성형성을 개선하여 개발된 고강도강인 TR590 및 DP590 소재로 대체하여 개발하였다. 이를 통해 각 부품의 충돌안전성에 대한 경량화 가능성을 연구하였다. 연구 결과 0.8 mm의 고장력강을 적용하게 되면 pillar-A inner upper 및 B-pillar inner 부품의 경우 20%의 경량화가 가능함을 확인하였다.

Evaluation of static belt fit and belt torso contact for children on belt-positioning booster seats

Objective: Previous studies have indicated that gap between the seatbelt and torso (reduced belt torso contact) for children on belt-positioning booster seats (BPBs) may lead to less torso engagement and increased likelihood of shoulder belt slip-off during evasive vehicle maneuvers, potentially increasing injury risk during crashes. However, current BPB belt fit measures do not quantify belt gap and may not be able to fully discriminate between designs which provide good vs. poor dynamic outcomes. The goal of this study was to evaluate both novel (belt gap characteristics) and conventional measures of seatbelt fit for BPB-seated children. Methods: Ten BPBs and three seatbelt anchor locations were investigated. Fifty volunteers (4-14 years) were recruited and each evaluated on six unique combinations of BPB and seatbelt anchor location on a vehicle rear seat in a laboratory setting. A 3 D coordinate measurement system quantified positions of anatomic, seatbelt, BPB, and vehicle reference points. Novel belt gap (gap size, length, location, and percent torso contact) and conventional belt fit (position of belt on shoulder and pelvis) metrics were calculated using anatomic and seatbelt landmarks. Variation in belt fit and belt gap outcomes due to BPB, seatbelt anchor location, and anthropometry were investigated. Results: BPBs produced significantly different outcomes, while seatbelt anchor location did not. BPBs with features that directly routed the lower portion of the shoulder belt more forward on the buckle side produced the largest (29.3 ± 12.6 mm) and longest (106.9 ± 68.2 mm) belt gap on average, while BPBs that pulled the belt less forward or did not directly route the belt produced the smallest (13.9 ± 6.7 mm) and shortest (16.9 ± 33.9 mm) gap on average. Belt gap outcomes were not strongly correlated with conventional belt fit metrics, indicating that evaluation of belt gap may provide additional insight when attempting to discriminate between BPBs which provide good vs. poor seatbelt engagement during vehicle maneuvers and crashes. Conclusions: This is the first study to evaluate belt gap characteristics for BPB-seated children. Results suggest that belt fit and belt gap are influenced by BPB design, particularly lower shoulder belt routings, and may have implications for belt engagement during dynamic events.

Enhanced Robust Design Optimization in Seat Belt Anchorage Strength for Front Crash Safety of Multi-Purpose Vehicle

This paper deals with an enhanced robust design optimization (RDO) method and its application to the strength design problem of seat belt anchorage, related to the front crash safety of multi-purpose vehicles. In order to determine the rational design safety of the newly developed automotive part, such as the seat, in which the reliability of the evaluation data is not sufficient at the design stage, it is necessary to implement a probabilistic design considering uncertainties. Thickness size variables of the seat frame structure’s members were considered random design variables, including uncertainties such as manufacturing tolerance, which are an inevitable hazard in the design of automotive parts. Probabilistic constraints were selected from the strength performances of the seat belt anchorage test, which are regulated in Economic Commission for Europe (ECE) and Federal Motor Vehicle Safety Standard (FMVSS), and the strength performances were evaluated by finite element analyses. The RDO problem was formulated such that the random design variables were determined by minimizing the seat frame weight subject to the probabilistic strength performance constraints evaluated from the reliability analyses. Three sigma level quality was considered for robustness in side constraints. The mean value reliability method (MVRM) and adaptive importance sampling method (AISM) were used for the reliability analyses in the RDO, and reliability probabilities from the MVRM and the AISM on the probabilistic optimum design were assessed by Monte Carlo simulation (MCS). The RDO results according to the reliability analysis methods were compared to determine the optimum design results. In the case of the RDO with the AISM, the structure reliability was fully satisfied for all the constraint functions, so the most reliable structural safety was guaranteed for the seat frame design.

Frontal crash seat belt restraint effectiveness and comfort accessories used by older occupants

Objective: Around a quarter of older occupants use some type of comfort or orthopedic aftermarket accessory on the vehicle seat while traveling in a vehicle. The aim of this study was to investigate the effect of comfort accessories on the performance of the seat belt restraint system in a frontal crash in terms of potential injury implications for older occupants.Methods: Eight frontal sled tests (43 km/h, 32 g) were carried out on a deceleration sled fitted with a three-point lap-sash seat belt and a front passenger seat from a common Australian passenger car for each test. A 5th percentile Hybrid III anthropometric test device (ATD) was positioned in the seat and measurements were recorded for head center of gravity acceleration, chest acceleration, neck forces and moments and sternal deflection. Tests were carried out in a baseline condition and with seven comfort accessories. Each comfort accessory was inserted between the ATD and vehicle seat as it is intended to be used, with the ATD otherwise positioned as close as possible to the baseline test position.Results: Initial distance between the seat belt anchor and ATD hip was associated with a statistically significant decrease in Head Injury Criterion and increase in sternal deflection. Submarining was related to the ATD torso recline angle and angle of the lap belt from the seat belt anchor.Conclusions: Accessories placed between the seat back and the lumbar region of an occupant have the potential to increase the risk of submarining due to a change in posture and should be avoided if such a change in posture when seated with an accessory is excessive. Sitting on seat cushions resulted in the greatest increase in seat belt anchor to hip distances and hence largest increase in sternal deflection. Given the fragility, frailty and particular importance of chest injuries among older vehicle occupants, further investigation is needed to determine whether these changes in ATD sternal deflection observed with seat cushion use results in injury threshold limits being exceeded and whether pretensioners and load limiters would ameliorate these effects without causing other negative changes in occupant response or kinematics.

PID Optimization Control of the Hydraulic System for Seat Belt Anchorage Strength Testing Equipment

Based on the hydraulic proportional loading system for the seat belt anchorage point strength test equipment, the AMESim simulation model of the hydraulic proportional loading system is established. After analyzing the AMESim model and performing dynamic and static characteristics analysis, it is found out that the hydraulic proportional loading system can be further optimized. The PID control optimization method is employed to improve the original proportional control system, After comparing the PID parameter setting with the system before and after optimization, it is shown that the performance of the optimized hydraulic proportional loading system is effectively improved.

Evaluación mediante software de la efectividad de los anclajes de cinturón de seguridad de un asiento comercial de autobús según la regulación ECE R14

El cinturón de seguridad es un elemento importante para mantener al ocupante sujeto al asiento durante un accidente; sin embargo, si el anclaje del cinturón no resiste durante la colisión, el ocupante es expulsado del asiento, por tanto, es indispensable analizar su efectividad. El objetivo de este trabajo es evaluar la resistencia de los anclajes para cinturones de seguridad de dos y tres puntos de anclaje de un asiento comercial de autobuses, aplicando la Regulación de la Comisión Económica de las Naciones Unidas para Europa (ECE-R14). Las propiedades de los materiales de la estructura del asiento y de los anclajes del cinturón se obtuvieron mediante ensayos de tracción y flexión. Estos valores se utilizaron para elaborar un modelo de elementos finitos utilizando el material Piecewise Linear Isotropic Plasticity de Ansys – LsDyna. Los anclajes se evaluaron aplicando fuerzas en los bloques pélvico y torácico sujetos a través del cinturón según lo especificado en la regulación. En el análisis los anclajes presentaron grandes deformaciones llegando a la ruptura, modificando la forma y posición de los anclajes e incrementando refuerzos estructurales en áreas de mayor solicitación los anclajes cumplieron con la regulación. Este trabajo pretende crear una metodología para la industria de asientos que permita evaluar sus modelos previos a homologaciones.

Analysis of Seat Belt Anchorage Strength for Vehicles

In order to improve the efficiency of seat design and enhance the safety of vehicle seats, it is necessary to carry out CAE analysis on seat safety before making physical tests. In this paper, the finite element analysis theory and HyperWorks finite element analysis software are applied in the pretreatment of vehicle seats, seat belts, as well as the upper limbs and buttocks of dummies. The loading time and load of the seat are set according to GB 14167-2013 of the People’s Republic of China, and CAE calculation is carried out based on LSDYNA software, obtaining the stress-strain nephogram of the corresponding vehicle seats. An improved scheme is proposed base on the analysis results, and CAE analysis is carried out on the improved seats again. The results of the analysis fully meet the national standard GB 14167-2013 and material strength requirements, which are of important guiding significance in reducing the development costs, shortening the development cycle and improving the passing rate of physical test.

A numerical study on the injury prevention for the occupants seated in aircraft side-facing seats

ABSTRACTDuring aircraft landing, passengers in side-facing seats suffer high risks of injury in the emergency braking. The objective of this study is to investigate how to improve the restraint system for passengers seated in side-facing seats. The finite element model of the typical side-facing seat using the European Side Impact Dummy-2 (ES-2) was developed and validated. Then, parametric studies were conducted to investigate the effects of seatbelt anchorage locations and armrest height on the occupant injury. In addition, this study further analysed the characteristics of occupant injury for multi-occupant collision condition. Results showed that seatbelt hanging point and left anchor point which were close to occupant centreline as well as the higher armrest could lower the risk of occupant injury. Multi-occupant study showed that the injury risks of head, neck and thorax of the occupant who was far away from armrest were more serious than the occupant near armrest, and the injury risks of the abdomen and pelvis of the occupant near armrest were more serious than the occupant far away from armrest. Moreover, when the contact between adjacent occupants occurred, increasing the distance between occupants could decrease the risk of occupant injury.

Evaluation of the influence of velocity on dynamic passenger loads during a frontal minibus impact against an obstacle

The safety of people travelling by minibus is a very complex issue, in which the decisive role is played by load-bearing vehicle structure, passenger seats, and personal protection means. In order to maximize the number of people transported, the seats are spaced very closely to each other and this may pose a hazard to the passengers. Based on an analysis of experimental test results, a computer model representing a system composed of a minibus floor segment, seats, and dummies was built. For the analysis, seats integrated with seat belts were adopted. A seat of this type was based on a high-rigidity frame necessary to bear, inter alia, the strong force exerted (during a collision) by passenger's torso on the shoulder seat belt and transmitted to the upper seat belt anchorage point on the seat backrest. Within this work, the frontal minibus impact against an obstacle with velocities ranging from 20 km/h to 70 km/h was considered.The analysis covered the motion of, and dynamic loads on, a test dummy representing a 50th percentile adult male (Hybrid III dummy). Within the analysis, realizations of dynamic loads caused by inertial forces and reactions exerted by a three-point seat belt were taken into account. Special attention was paid to the extreme values of the loads that acted on dummy's head, neck, and torso when the head hit the backrest of the preceding seat in the culminating phase of the vehicle impact against an obstacle. The values of biomechanical indicators HIC, ThAC, Nij, and FAC and of the joint injury risk indicator were calculated.

A computational study of seat and seatbelt performance for protecting 6-12 year-old children in frontal crashes

The purpose of this study is to examine the effects of the body size for 6-12 year-old children as well as belt and seat design factors on injury outcomes in frontal crashes using computational simulations. Custom software was created to automatically scale and position a MADYMO child dummy model with an improved pelvis and abdomen geometry from child data. A parametric analysis of the effects from child size, seat belt anchorage locations, seat cushion length and seat stiffness on the injury predictors of child passengers aged between 6 and 12 in the FMVSS213 crash scenario was conducted. Child size was the dominant variable affecting the outcome measures. Seat design variables and the seat belt system variables had opposing effects on outcome measures, particularly between head and knee excursions, highlighting the importance of using optimisation techniques for future seat belt and seat designs to improve rear seat older child protection.

Influence of the edge rounding process on the behaviour of blanked parts: numerical predictions with experimental correlation

Blanking of sheet metal is an important forming process in the automotive industry for the manufacture of mechanical components. The final component shape, obtained at the end of bending or deep-drawing processes, often has sharp edges due to the blanking operation. Concerning passenger safety components, like seat belt anchors, rounding of the edges by punching is necessary to avoid cutting the belt material. In addition to removing the sharp edges, the punching results in work hardening of the material in the rounded zones which results in an increase in the local resistance of the material. In this study, a high-strength low-alloy steel (HSLA S500MC) has been tested with the aim of quantifying the blanking and edge rounding operations. The mechanical behaviour of test specimens is investigated by means of tensile tests and the material is characterised in terms of Vickers micro-hardness. Numerical simulations of the edge rounding process are developed using previously identified material behaviour laws. The residual stress fields are characterised and compared to experimental results. This is done so that numerical simulation can be done in the future to prediction the in-service behaviour of the component. Specimens with rounded edges are compared to specimens that were not submitted to the rounding operation. It is shown that Edge Rounding by Punching improves the component resistance, therefore justifying the use of this process in the manufacture of automotive safety components.

Rear Seat Restraint System Optimization for Older Children in Frontal Crashes

Objective: Analyses of crash injury data have shown that injury risk increases when children transition from belt-positioning boosters to the vehicle seat belt alone. The objective of this study is to investigate how to improve the restraint environment for these children. Methods: A parametric analysis was conducted to investigate the effects of body size, seat belt anchorage locations, and rear seat design parameters on the injury risks in frontal crashes of children aged 6 to 12 years old using a newly developed parametric child anthropomorphic test dummy (ATD) model. Restraint design optimizations were also conducted to obtain ranges of optimal restraint system configurations that provide best protections for 6-, 9-, and 12-year-old children. Results: Simulation results showed that child body size was the dominant factor affecting outcome measures. In general, lower and more rearward D-rings (upper belt anchorages), higher and more forward lap belt anchorages, and shorter, stiffer, and thinner seat cushions were associated with improved restraint performance. In these simulations, children with smaller body sizes require more-forward D-rings, inboard anchors, and outboard anchor locations to avoid submarining. However, these anchorage locations increase head excursions relative to more-rearward anchorages. Conclusions: The balance of reducing head and knee excursions and preventing submarining indicates that an optimization approach is necessary to improve protection for 6- to 12-year-old child occupants. The findings of this study provided design guidelines for future rear seat restraint system. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

Distribution of Belt Anchorage Locations in the Second Row of Passenger Cars and Light Trucks

Seat belt anchorage locations have a strong effect on occupant protection. Federal Motor Vehicle Safety Standard (FMVSS) 210 specifies requirements for the layout of the anchorages relative to the seating reference point and seat back angle established by the SAE J826 H-point manikin. Sled testing and computational simulation has established that belt anchorage locations have a strong effect on occupant kinematics, particularly for child occupants using the belt as their primary restraint. As part of a larger study of vehicle geometry, the locations of the anchorage points in the second-row, outboard seating positions of 83 passenger cars and light trucks with a median model year of 2005 were measured. The lower anchorage locations spanned the entire range of lap belt angles permissible under FMVSS 210 and the upper anchorages (D-ring locations) were distributed widely as well. Combined with the findings from concurrent research on the effects of belt geometry, these results suggest that occupant kinematics in frontal impact can be expected to differ widely across vehicles due to differences in belt geometry. Language: en

Effectiveness evaluation for seat parts by seat belt anchorage strength analysis

Many different laws are being to be considered to meet the requirement for the production of automobiles, which laws are diverse on each country. So, the laws were compared and analyzed in order to make an optimizing drawing in the field of seat. A test method and FEM (finite element method) were performed for the seat according to the seat belt anchorage strength test process. Major parts of seats were evaluated which impact on seat belt anchorage strength. This paper suggests the minimum yield stress of part which is connected to upper rail and set-bracket and rails which translocate seat to satisfy automobile safety-related laws on each country. It also describes the evaluation procedure of seat belt anchorage in FEM.

Assessment of seat belt webbing bunching phenomena

In current cars, loops are commonly used to redirect the webbing which reels out from the retractor to the passenger’s shoulder. Some types of pillar loops, also called D-rings, lead to a non-systematic instability. The webbing, which should scroll without hindrance through the D-ring, laterally shifts, bunches and produces the overturning of the ring. This paper presents the in-depth assessment of the phenomenon based on the experimental and numerical tools previously developed and published. A macroscopic analysis of the early rotation of the ring is presented, and its consequences on the webbing load distribution are analysed. The resisting torque of the D-ring pivot joint under load is investigated experimentally. The overturning of the D-ring is next decomposed in two phases; the lateral shifting of the webbing followed by the overturning of the ring. The first phase is mainly explained by lateral forces generated by the seat belt anchor’s position, and the angle position of the ring is demonstrated to be controlled by a set of resisting/resulting torques. The dynamic equilibrium of a seat belt assembly is then assessed. Based on forces and torques acting on the D-ring, an explanation scheme of seat belt bunching phenomena is proposed. To investigate the potential counter measures, a sub-system test is used and a Finite Element model of seat belt bunching is validated by comparison with experimental results. A numerical sensitivity analysis is eventually undertaken to organize into a hierarchy the parameters which influence the seat belt bunching phenomena. The main factors are varied and the consequences on scrolling length before bunching are examined. The most favourable combination of parameters is tested numerically on a sled test and the instability is avoided.

농용트랙터 보호구조물 사용실태 및 좌석벨트 편이성 평가에 관한 연구

This study was performed to improve the utilization of the ROPS and seatbelt of tractors in Korea. We surveyed the ROPS and seatbelt use and the tractor related accidents through the personal interviews for 141 farmers. And comfort test for tractor seatbelts is done for 4 different subjects by measuring the body pressure distribution. The survey showed that 79.3% of the tractor accidents was overturning accidents. And, in case the tractor has ROPS and seatbelt, there was no serious injuries. With this results, we could confirm that ROPS and seatbelt is very effective devices for protecting drivers in overturning accidents. But, in case farmers didn't wear seatbelt, there was some fatal injuries. This shows the importance of the seatbelt use in working and driving tractors. Therefore, we tested the comfort of the tractor seatbelt for 4 different subjects operating the pedal in tractor seat simulator and in the tractor running on various roads. From the results of the static test in the Lab, it was shown that more the seatbelt anchorage point is far form SIP point, more the body pressure of the belly became higher, and more the subjects feel uncomfortable. Not only in the static test in the simulator, but also in the dynamic test in riding tractors, it was shown that non retractable seatbelt was more uncomfortable than retractable seatbelt. According to this study, we concluded that we need to promote the utilization of the ROPS and seatbelt use. And, the non retractable seatbelt need to be replaced by retractable seatbelt. Also, we recommend that the seatbelt anchorage position should to be in the seatbelt anchorage area of the ISO 3776 standard.

Evaluation criteria for the anchorage resistance of safety belts on agricultural tractors

The Society of Automotive Engineers (SAE), the International Organisation for Standardisation (ISO) and the European Community (EC) testing procedures for tractor seat belt anchorages are compared. Eight tractors, each one fitted with different driving seats, with total number of 26 drivers seats were tested. The tests showed that the operator restraint system has to be considered complementary to the safety level, ensured by the protective structure. The reason is, that while the Roll-Over Protective Structures (ROPS) guarantees a survival volume for the driver, the seat belt anchorage and seat belts themselves have the effect of restraining the driver inside that volume when it is overturned. The results demonstrate that the Directive 76/115/EEC foresaw a load of 22 250 N as being too high for the pelvic restraint systems fitted on agricultural tractors. The SAE J2194 standard, which considers not only seat belt anchorage but also seat mounting, appeared more effective than the ISO 3776, because the seat mounting proved to be the part of the operator restraint system that broke first in the test. On the basis of these results a testing procedure for seat belt anchorage strength, derived from the SAE J2194 procedure, has been included as an optional test in ROPS Codes of the Organisation for Economic Co-operation and Development (OECD).