Q: I have a situation where a pickup struck the side of a semi trailer between the landing gear and the trailer's wheels. The trailer was at a 30 degree angle to the pickup and the pickup skidded straight into the collision. Any information on this type of damage?
A: NOTE: In an angled underride crashes, not all the energy goes into the vehicle crush. A significant amount of energy may be dissipated as the vehicle moves and slides and gouges subsequent to the initial impact. I would suggest brushing up on some of the concepts of Energy Correction Factor(ECF).
There are many angled barrier crash tests whcih are included in the database. McHenry Software Users, from medit32, simply select Databases->NHTSA Databases w/Extended data
The following are 2 papers on underride collisions.
Abstract: Compatibility or aggressivity between vehicles in frontal crashes can be manifested by differences in the ways that upper and lower structures deform, when compared to each other, or when compared to the deformation modes in full-width impacts into rigid barriers. Flat barrier tests are very useful for characterizing the structure and determining the crush energy, and are indeed the underpinning of existing reconstruction methods. However, conventional methods can be problematic when flat barrier test data are applied to underride/override crashes. Useful insights in grappling with such situations were obtained by analyzing a series of NHTSA-sponsored crash tests into full-width rigid barriers, in which advanced measurement protocols were employed. Dynamic force-deflection characteristics were developed, and absorbed energies were calculated, for the upper and lower structures of the tested vehicles. Distinct CRASH III-type models were developed for these structures. For all the other crash test data not employing advanced measurement protocols, a means was developed for approximating the crush energy contributions from the upper and lower structures, based on data from full-width rigid barrier impacts. To test its validity for under/override crashes, the method was applied to published crash test data for some repeated frontal impacts into an overhanging barrier. Good predictions of the crush energy were obtained. The paper contains recommendations for future measurement protocols, and how to use the developed procedures for vehicles not tested according to improved protocols.
Limitations “The proposed underride/override model has been validated against a very narrow range of vehicles only. It should be tested against other staged underride/override crashes as they become available.”
Abstract: Crashes between passenger vehicles and large tractor trailer vehicles often result in serious injuries and death. There have been few studies of this class of crash involving the side of the large tractor trailers and the passenger vehicles. Studies have shown that side underrides are underreported in crash records. A literature search has shown that there are no generally accepted methodologies to document and scientifically reconstruct a side underride accident. Some of the problems existed because there was a general lack of information on the side underride crash. Rear underride crashes were being studied which yielded helpful information. This led the authors to study a series of trailer side underride crashes that were performed to determine if there were sufficient relationships between passenger vehicle body and roof styles and the side of large highway trailers to allow the development of a general formula for underride impact speed analysis of a vehicle where the roof and roof support structure of the vehicle was damaged. These tests provided valuable insight into the relationships between passenger vehicle roof structures and the sides of large box trailers.
PURPOSE AND TEST PROCEDURE
The purpose of the four (4) heavy truck rig id rear underride guard impact. tests was for research and development in support of the CRASH3
damage algorithm reformulation. The 1990 Ford Taurus was equipped with a 3.0-liter, 6-cylinder, transverse, gasoline engine with a 3-speed automatic transmission. The test weight of the vehicle was 3331 pounds. The vehicle was instrumented with six (6) accelerometers to measure vehicle X-axis and Y-axis acceleration.Each crash test event was recorded by two (2) high-speed motion picture cameras operating at approximately 1000 frames per second.
AbstractAccident reconstructionists are often faced with damage patterns and locations on vehicles that are not well defined by available barrier impact data. One such example is a frontal underride collision. Underride impacts occur when there is a height mismatch between the primary structural components of the impacting vehicles, and the vehicle with the lower height is forced beneath the structure of the other vehicle. The lack of structural engagement typically allows for significantly different damage patterns due to the inherently lower stiffness of the underriding vehicle's contacting surfaces coupled with complex interactions between varying surfaces. In this study, a series of two-vehicle impact tests between a small pickup (bullet vehicle) and a large dump truck (target vehicle) were performed and studied. These tests involved a severe underride configuration in which the dump truck bed's vertical alignment was above the base of the windshield of the pickup. Coupled with these impacting surfaces was a single vertical support, a remnant of a commonly referred to ICC (Interstate Commerce Commission) bumper, which caused a narrow object-type impact, but did not extend down to the pickup's bumper. Multiple prior authors’ analytical and empirical relationships to predict impact speed based on crush damage were evaluated using the results of these tests as well as other published underride tests. No single model was sufficient at predicting the mixed mode of impact present in these impact scenarios. However, a system of equations was developed to predict the impact parameters utilizing a combination of previously reported methods and a new empirical relationship presented in this study. This new method shows high correlation and supports the authors’ hypothesis that separate crush models can be applied to multiple discrete areas of a vehicle and then combined to form a more complete predictive systematic model.
In automobile accident reconstruction it is often necessary to quantify the energy dissipated through plastic deformation of vehicle structures. For collisions involving the front structures of accident vehicles, data from Federal Motor Vehicle Safety Standard (FMVSS) 208 and New Car Assessment Program (NCAP) frontal barrier impact tests have been used to derive stiffness coefficients for use in crush energy calculations. These coefficients are commonly applied to the residual crush profile of the front bumper in real-world traffic accidents. This has been accepted as a reasonable approach, especially if there has been significant involvement of the front bumper and its supporting structures. For impacts where the structures above the bumper level are deformed more than the bumper itself, this approach may not be so readily applied. These types of impacts are called override/underride, and are encountered quite often in truck-to-car accidents where there is a vertical difference in bumper heights and also in accidents where bumper height mismatches are created through vehicle brake dive. In this paper we examine the crush-energy considerations of override/underride impacts. The limited available literature and test data are reviewed. Two test programs that involved impacts over a wide range of severities are analyzed in detail.
The first objective of this paper was to evaluate a public domain finite element (FE) model of a 1990 Ford Taurus from the perspective of crush energy absorption. The validity of the FE model was examined by first comparing simulation results to several published full-frontal crash tests. Secondly, the suitability of the model for underride simulation was evaluated against two series of full-scale crash tests into vertically offset rigid barriers.
Next, the evaluated FE model was used to pursue the main objective of this work, namely to develop an approach for estimating underride crush energy. The linear-spring methodology was adopted whereby the underride crush stiffness was determined by relating the residual upper radiator support deformation to crush energy. An underride crush stiffness estimation method was proposed based on modifying the full-frontal stiffness coefficients. The method was further simplified into a “Rule-of-Thumb” estimation method, and an example of its application was provided along with a discussion of its estimation accuracy.
In past years, considerable research has been devoted to occupant response in a variety of low-velocity, bumper-to-bumper impacts. In many crashes, however, the involvement of a braking vehicle or a higher ground clearance vehicle results in an override/underride type crash. The amount of vehicle damage can be significantly greater during such an impact because of the involvement of non-structural components above and below the bumper systems of the involved vehicles.
Ten tests were conducted using five target vehicles, each occupied by an instrumented female driver. Each vehicle was tested in a bumper-to-bumper impact and then an override/underride configuration in increasing severity. An independent body shop estimator was employed to document the damage and prepare repair estimates for each test. In each test the vehicle and occupant accelerations were monitored. A comparison of these data collected is presented herein to provide additional insights into override/underride crashes versus bumper-to-bumper impacts.
In automobile accident reconstruction it is often necessary to quantify the energy dissipated through plastic deformation of vehicle structures. For collisions involving the front structures of accident vehicles, data from Federal Motor Vehicle Safety Standard (FMVSS) 208 and New Car Assessment Program (NCAP) frontal barrier impact tests have been used to derive stiffness coefficients for use in crush energy calculations. These coefficients are commonly applied to the residual crush profile of the front bumper in real-world traffic accidents. This has been accepted as a reasonable approach, especially if there has been significant involvement of the front bumper and its supporting structures. For impacts where the structures above the bumper level are deformed more than the bumper itself, this approach may not be so readily applied. These types of impacts are called override/underride, and are encountered quite often in truck-to-car accidents where there is a vertical difference in bumper heights and also in accidents where bumper height mismatches are created through vehicle brake dive. In this paper we examine the crush-energy considerations of override/underride impacts. The limited available literature and test data are reviewed. Two test programs that involved impacts over a wide range of severities are analyzed in detail.