Underride Guards Research Articles

A proposed quasi-static test for improving the crash performance of trailer rear underride guards

Current U.S. and Canadian regulations for rear underride guards on large truck trailers do not promote designs with adequate protection in offset crashes. The objective of the current study was to determine whether a quasi-static evaluation could distinguish between underride guards with different performance in offset crash tests. Five different underride guard designs were evaluated in quasi-static testing. These designs were previously tested in 56 km/h impacts with a midsize passenger car with 30 or 50% overlap. Three of the guards exhibited marginally passing performance in the crash test, with car excursion under the rear of the trailer reaching the base of the windshield but stopping prior to trailer-to-dummy contact. The other two designs failed to prevent trailer-to-dummy contact. Two quasi-static test configurations were assessed for their potential to distinguish between the marginally passing and the failing designs: the outboard P1 test in the existing regulation and a new 20-degree-angled test developed using crash test acceleration measurements. In both configurations, the guard designs with marginally passing crash test results demonstrated higher force and energy levels than the designs with failing crash test results. However, the 20-degree-angled test showed greater differentiation between levels of crash test performance while also producing more representative damage patterns. Underride guards that prevented trailer-to-dummy contact in the crash tests sustained quasi-static force levels of a least 100 kN prior to 75 mm of displacement in the 20-degree test. Rear underride regulations could be improved by replacing the outboard P1 test with a 20-degree-angled load applied to the end of the underride guard. This evaluation also could supplement or replace underride guard crash tests conducted by the Insurance Institute for Highway Safety (IIHS).

Evaluation of General Motors Event Data Recorder Performance in Semi-Trailer Rear Underride Collisions

<div class="section abstract"><div class="htmlview paragraph">The objective of this study was to analyze the validity of airbag control module data in semi-trailer rear underride collisions. These impacts involve unusual collision dynamics, including long crash pulses and minimal bumper engagement [<span class="xref">1</span>]. For this study, publicly available data from 16 semi-trailer underride guard crash tests performed by the Insurance Institute for Highway Safety (IIHS) were used to form conclusions about the accuracy of General Motors airbag control module (ACM) delta-V (ΔV) data in a semi-trailer rear underride scenario. These tests all utilized a 2009 or 2010 Chevrolet Malibu impacting a stationary 48’ or 53’ semi-trailer at a speed of 35 mph. Nine tests were fully overlapped collisions, six were 30% overlapped, and one was 50% overlapped [<span class="xref">2</span>]. The IIHS test vehicles were equipped with calibrated 10000 Hz accelerometer units. Event Data Recorder (EDR) data imaged post-accident from the test vehicles were compared to the reference IIHS data. For each test, root mean square error (RMSE), the percent error over time, and the difference between the EDR ΔV and the IIHS ΔV, was quantified, plotted, and related to crash pulse. This analysis revealed a general trend of decreasing EDR ΔV parity with an increasing crash pulse duration, although overall differences remained low for most tests. Eleven tests, all with airbag deployments, converged towards an average of 3.3% error at the end of the crash pulse, which were 150-270 ms. EDR recorded ΔVs were in the range of 29.8-39.9 mph. Five tests, three of which were non-deployments, diverged to higher percentage error averaging 12.7% at an EDR ΔV of 31.8-40.0 mph. All higher error tests were 30% overlapped and had the highest crash pulse durations of 240-300 ms. One fully overlapped test generated highly unusual EDR data due to failure of the rear underride guard mounting bolts and plates.</div></div>

Selection of design variables using complex proportional assessment and analysis of a rear underride protection device

Road accidents between cars and trucks have the highest fatal accidents ratio because of cars under running beneath trucks which leads to serious and fatal injuries for car’s occupants. The improper design of the underride guard system for trucks fails to prevent passengers of small vehicles from fatal injuries in collision with rear of heavy trucks. This research developed a new rear underride protection device for heavy trucks. Five design concepts are developed for the basic part of the underride guard device. Complex proportional assessment method was used to select the best design concept, while finite element analyses software ABAQUS was used to simulate and examine the structural behaviour of the underride guard (design A) comparing with the basic underride guard (design C). The simulation is specified a termination time 0.2 sec, where simple rigid plate is used as impactor with speed of 63 km/h before hitting the underride guard assembly in the truck. The FMVSS 223/224 regulations were utilised to validate the developed underride guard. The results showed that design (A) achieved the goal of decreasing the acceleration to (15.83 g) beyond the limits (60 g), enhanced the energy absorption by 88.32%, and accomplished minimal passenger compartment intrusion.

Design and simulation of a rear underride protection device (RUPD) for heavy vehicles

ABSTRACTEvery year, thousands of deaths are recorded worldwide due to crashes of small cars with heavy trucks. The highest risk during collision of passengers’ car with a truck is the intrusion of passengers’ compartment under the heavy truck rear underride leading to cause fatal injuries to passengers. Design of robust underride guard of truck is one of the significant factors that should be taken into consideration within design and enhancement of truck chassis. In this study, a new rear underride protection device (RUPD) based on FMVSS 223/224 regulations is developed to enhance the crashworthiness and reduce passenger compartment intrusion under heavy trucks during accident. Finite element simulation is utilised for performance analysis of the RUPD in LS-DYNA. The results showed that the new RUPD design enhanced the energy absorption by 68.87% and reduced the occupant's car deceleration by 66.116%. The new guard is able to avoid underride of Toyota Yaris (2010) colliding at 45, 54 and 63 km/h compared with the normal guard that failed under the same test conditions.

Behaviour of passenger cars on impact with underride guards

Much experience has been gathered on the impact behaviour of passenger cars crashing against flat barriers. This is quite different from impacting underride guards at the rear end of commercial vehicles. The side members in the car's front structure are the main energy absorbing structural elements, thus it is of considerable significance whether they hit on the underrider beam. Thirty–four clash tests were carried out in order to measure impact forcer and deformations. The quadstatic crush forces of simplified side members can be calculated by approximation on the basis of many experimental results. A ratio of crash to crush forces was found from dynamic impact and static crush tests. The frontal impact of a passenger car on a flat barrier was simulated by crashing a simplified structural model consisting of an engine, gearbox, and front–axle, etc. The required strength of an underride prevention device can be found from the deformation resistance of the ramming car's front structure. The weight of the commercial vehicle carrying the underride guard has little influence on the impact force and deformation because as the kinetic energy to be absorbed does not decrease in proportion as the commercial vehicle's weight is reduced and, because of its inertia, the vehicle hardly moves until the peak clashing load is reached. Quasistatic strength requirements are presented as an aid in the design of underride guards.

Development of a regulation for testing the effectiveness of a rigid side underride protection device (SUPD)

The development of a side underride protection device is a crucial aspect for improving the safety of small car to tractor–trailer collisions. Devices such as rear underride guards are already implemented and regulated in North America and many places around the world along with front underride devices, which are regulated in Europe. The large and unprotected gap between the rear axle and the kingpin of the trailer remains a hazard for small passenger vehicles passing underneath. To develop devices to prevent such accidents, a regulation for testing the underride guards must be implemented to determine their feasibility. This paper describes the background information and testing procedures of the existing regulations for front and rear underride guards to help develop the side regulation. A finite element tractor–trailer model is presented and a component model based on the trailer is created and validated in order to be used for simulations. Collisions with small passenger cars such as the National Crash Analysis Center's Toyota Yaris and Ford Taurus into rigid walls are conducted and methods are introduced to obtain a quasistatic model from the dynamic crash. Device dimensions are determined using tractor–trailer models in TruckSim in order to obtain the maximum allowable ground clearance of the devices. Feasible rigid guards are then created and tested with the proposed quasistatic regulation and compared to the results obtained from the dynamic tests.

Potential Benefits of Underride Guards in Large Truck Side Crashes

Objective: To evaluate the maximum potential for side underride guards (SUGs) to reduce passenger vehicle occupant fatalities and injuries in crashes with large trucks in the United States. Methods: Examination of the Large Truck Crash Causation Study (LTCCS) identified 206 crash events involving a passenger vehicle impact with the side of a large truck. Each case was evaluated to determine whether the most severe injury sustained by a passenger vehicle occupant was a result of the impact with the side of the truck and whether an SUG could have reduced the injury severity. Data from the 2006–2008 Fatality Analysis Reporting System (FARS) and Trucks Involved in Fatal Accidents (TIFA) survey were used to compare the types of trucks involved in all fatal side impacts with passenger vehicles with the truck types in the LTCCS cases that were studied. FARS and TIFA data also were used to estimate the total annual number of passenger vehicle occupants killed in truck side impacts. Results: In 143 of the 206 cases, the truck side impact produced the most severe injury sustained by a passenger vehicle occupant. In the other cases, no passenger vehicle occupant was injured or the most severe injury was due to an event preceding or following the truck side impact. Forty-nine of these occupants sustained injuries coded as level 3 or higher on the abbreviated injury scale (AIS) or were killed. SUGs could have reduced injury severity in 76 of the 143 cases, including 38 of the 49 cases with an AIS ≥ 3 coded injury or fatality. Semi-trailers were the most common type of impacted truck unit, both overall and when considering only cases where an SUG could have mitigated injury severity. Crashes where the front of the passenger vehicle struck the side of the semi-trailer perpendicularly or obliquely from the oncoming direction were less common overall than side-to-side and oblique/same direction crashes but more often produced an AIS ≥ 3 injury or fatality. The distribution of truck types in the LTCCS sample was similar to that in the FARS and TIFA data. Overall, around 1600 passenger vehicle occupants were killed in 2-vehicle truck side impact crashes during 2006–2008, or 22 percent of all passenger vehicle occupants who died in 2-vehicle crashes with large trucks. Conclusions: Structural incompatibility was a common factor in LTCCS crashes between passenger vehicles and the sides of large trucks. SUGs could have reduced injury risk in around three fourths of the crashes that produced an AIS ≥ 3 injury or fatality. Most of these crashes involved semi-trailers. However, the necessary strength and location of these SUGs present technical challenges that need to be addressed.

Influence of a Truck Side Under-ride Guard Height on Cabin Intrusion and Occupant Injury Potential of a Small Car in Car/Large-Truck Side Crashes

In car/large truck collisions, the size, weight, and stiffness mismatch results in a much larger structural deformation of the car compared to that of the truck, and larger potential for car occupants injuries. This is further aggravated when the passenger vehicle trends beneath the rear or side of the taller truck. In the US, under-ride guards are required only for the rears of large trucks, although the review of fatal truck-car crashes in the NCSS/CDS indicates that fatal under-ride crashes involving the sides of large trucks are almost as common as fatal rear under-ride crashes. A methodology using validated finite element models of a passenger car and a truck is utilized in this study to quantify the influence of a side guard attached to a large truck in reducing the intrusion of the car and thus reducing the injury sustained by the occupants of a car in a side crash. A formulation is proposed based on a normalized passenger compartment intrusion and its relation to the occupant injury potential. The transmitted deceleration severity and the occupant compartment intrusion are evaluated for the car impacting a rigid under-ride guard. A NHTSA under-ride test is simulated first for model validation. Once model validation is conducted for a specific guard design, further simulations are conducted at the speed range of 30 to 50 mph and for 90 and 45-degree impact angles. The results from a parametric study are used to identify the critical guard height resulting in severe cabin deceleration and compartment intrusion of the small car. This study quantifies the vulnerability of car occupants in truck side under-ride crashes and the effectiveness of side guard at different ground heights in reducing the injury potential to car occupants.

Analysis of the Influence of Energy Dissipative Under-Ride Guard's Parameters on Car-to-Truck Collision

Rear underrun crashes involving heavy vehicles have the most tragic consequences. This paper describes the concept of a special energy dissipative rear under-ride guard. A dynamic model of a car-to-truck collision was built where the truck had been equipped with such a guard. Simulation research of this model was made. The purpose of this study is to determine the influence of linear and non-linear characteristics of stiffness and damping on the collision course. Maximal value of the car deceleration during the collision was chosen as the major criterion of the bumper quality. The analyses confirm that the proposed bumper, in spite of the concept's simplicity, can be a very effective way of providing security during such a car-to-truck collision. (A)

Design and simulation of an energy absorbing underride guard for heavy vehicle rear-end impacts

Recent passenger car-heavy vehicle rear-end crashes demonstrate the importance of rear underride guard designs for heavy vehicle applications. Currently specified rear underride guards have many shortcomings, such as structural strength and energy dissipation capacity, clearance from ground, and other design aspects. As a result of these inadequacies in underride-guard design, many lives are lost every year when passenger cars slide underneath heavier vehicles. In this study, design modifications to an underride guard that minimally complies with the requirements contained in FMVSS 223/224 are evaluated. A previously performed crash test on the guard using a compact passenger car demonstrated the potential for excessive vehicle underride and passenger compartment intrusion problems. After the full-scale crash test, a detailed finite-element study is performed to investigate the shortcomings of the design. The accuracy of the underride guard model is partially validated using both a quasi-static and a full-scale crash test. After the validation, the guard is modified to improve its structural behaviour and energy-dissipation capacity. Four crash-test simulations are performed on the modified guard model to verify its effectiveness in energy dissipation and preventing intrusion into the passenger compartment. In these simulations, two vehicle speeds of 48 km/h and 56 km/h and two impact positions of 0% and 50% offsets are used to fully verify the acceptability of the modified guard model. Simulation results show that the modified rear underride guard performs much better than the original design. The guard dissipated a significant amount of the impacting vehicle's energy and showed no potential for passenger-compartment intrusion in any simulation. The deceleration of the vehicle was also within acceptable limits. Based on these results, it can be concluded that the improved guard performed well and the implementation of this particular underride guard on heavy vehicles looks promising.

STUDY OF AN ENERGY DISSIPATING UNDER-RIDE GUARD USING HARDWARE-IN-THE-LOOP SIMULATION

Hardware-in-the-Loop (HIL) simulation technique is implemented to analyze the performance characteristics of an energy dissipative under-ride guard system for enhancement of crashworthiness of lightweight vehicles involved in coillisions with heavy freight vehicles. The experimental setup, software and hardware interface, and the test methodology used to perform the HIL simulation are briefly described. The energy dissipating under-ride guard, while impacted by a car body, is analytically modeled incorporating nonlinearities due to asymmetric damping in compression and rebound, restoring properties and kinematics of linkages, using the principles of conservation of momentum and Lagrangian dynamics. The performance characteristics of the under-ride guard are evaluated under direct impact at different speeds, and the results obtained from the HIL simulation are compared with those derived from the nonlinear analytical model. The study revealed very good correlation between the analytical and experimental findings in terms of the amount of energy dissipated, acceleration level, rebound velocity and the magnitude of intrusion. An analysis of the results showed that significant portion of the kinetic energy can be dissipated by the under-ride guard.

Study of an energy dissipative under-ride guard for enhancement of crashworthiness in a car-truck collision

The performance potentials of a concept of an energy dissipating under-ride guard are investigated under direct and oblique impacts to enhance the crashworthiness of automobiles involved in collisions with heavy freight vehicles. The under-ride guard is analytically modelled incorporating non-linearities due to asymmetric damping, stiffness, clearance spring and kinematics of linkages, using the principle of conservation of momentum and Lagrangian dynamics. Hardware-in-the-loop tests are performed to evaluate the impact energy dissipated by the damper and to verify the proposed model. The analysis is performed for different angles of impact and coefficients of friction between the automobile bumper and the under-ride guard. The performance benefits of the proposed guard at different impact angles are investigated using performance criteria based upon the magnitude of intrusion of the car mass, peak car mass acceleration, and dissipated energy. A multi-variable design optimisation is performed to minimise the magnitude of intrusion and peak acceleration, and maximise the energy dissipated by the damper. The results of the study show that the severity of a crash involving an automobile and a heavy vehicle can be significantly reduced by the proposed guard by: (1) limiting the magnitude of intrusion; and (2) dissipating the part of the crash energy through the damper.