Vehicle: 1993 Jeep Grand Cherokee (Sister & Clones: 1993-1998 JG Cherokee)

The 1993 Jeep Grand Cherokee posed some interesting challenges while being tested for its HALO™ design. Due to having a very weak overall roof structure, designing a HALO™ that provides adequate safety during a rollover but does not interfere with internal space or safety devices was a challenge.

About the JRS method

The Jordan Rollover System is operated by the non-profit; Center for Injury Research. It is a versatile, realistic, and repeatable rollover testing system capable of assessing vehicle structural design and performance. Due to the JRS testing ability to control various dynamic testing conditions we are able to put the HALO™ through a rigorous validation process and are confident it will significantly reduce vehicle roof intrusion in rollovers.

Testing the HALO™

Jordan Rollover System – Dynamic Vehicle Rollover Testing

Due to the amount of unique vehicles all with their own shapes, structural components and fitting challenges, creating a HALO™ template is just as unique. Here we walk you through the process from testing to design, see what goes into a HALO™.

Testing the Stock Vehicle

We first tested the production version of the vehicle allowing us to see the structural failure points and to address them accordingly.The first video shown is the outside view of the test of the production version of the 1993 Jeep Grand Cherokee. As you can see the roof is very weak and provides little protection during the rollover. In fact, it crushes the “A” pillar 10.1 inches (277 cm) and had an intrusion speed of 9.94 mph (16kph).

Interior Views of Dynamic Testing

The following video shows the interior view of the production version of the 1993 Jeep Grand Cherokee. Notice that the roof crushes in and down on the driver occupant. This can result in serious to fatal head and neck injuries. The roof is very weak and provides little protection during the rollover. Take a look at the next videos to see how the HALO stopped this from happening.

Introducing the HALO™

Here we’ve outfitted the same model vehicle, a 1993 Jeep Grand Cherokee, with our HALO™ and tested it with the same rollover protocol. As you can see there is a major reduction in the amount of roof crush.

Inside View with HALO™ Outfitted

Looking inside during a rollover with the HALO™ outfitted, it’s hard to tell when it is actually contacting the ground. There is very little movement of the roof in any direction. The HALO™ distributes the forces across the roof and prevents buckling or failures in single specific locations.

Post Test Analysis

Here we are able to easily compare the results of a rollover test with a HALO™ outfitted (top) and without the HALO™ (bottom). You can see that the roof deformation in the production vehicle is significant over the driver’s position and that there is little deformation with the HALO™

What We Learned

After the JRS Test we concluded that the vehicles B-pillars (the pillar between the front and rear door) needed reinforcement. The reason for this is that when the vehicle rolls over onto its roof, the weight of the vehicle is transferred to the roof structure, the pillars that are connected to the roof connect to the rest of the chassis, if these pillars are not strong enough the roof will continue to crush into the occupant compartment.

Graphing the Results

Displaying the results graphically you can see the amount of roof crush into the occupant compartment. The results of the production vehicle compared to a HALO™ outfitted vehicle are shown below. The red line represents the Far side A Pillar intrusion and the blue line represents the loading of the roof. Both lines are flattened out with the HALO™. Additionally, the HALO™ equipped vehicle was tested at a more severe protocol and still out performed the production vehicle.

Results

The final 1993 Jeep Grand Cherokee design for the SUV-LTV HALO™ incorporates what we learned from the dynamic rollover testing, including optimization of attachment points to displace and distribute loading and reinforcement strengthening of the b-pillar. The HALO™ will significantly reduce the likelihood of injury to occupants in rollover crashes.