Collision Survival
By DJ DeVeau

While we work on the funding to build three of the full size prototypes for collision testing at 62mph [100kph], I decided to build one myself.

This is a 1/16 scale of this prototype with a separable occupant safety cage compartment and a full frame shielded collision force absorption zone.

NOTE; 1/16 Scale Model Is Applicable To Full Scale Prototypes & Collision Tests

The full-scale design uses 1-1/2 x 1-1/2 inch [38mm] and 4 inch [100mm] x 8 inch [200mm] thin wall steel tubing and 1/8 inch [3mm] thick steel sheet.

This design uses 3/32 x 3/32 inch [2.5mm] and 1/8 [3mm] inch x 1/4 inch [6mm] thin wall brass tubing and 0.01 [0.25mm] thick brass sheet and of course has been even more simplified.

Here are some of the fabrication details...

First I cut all the little stock lengths to match a 1/16 scale printout of the prototype cage and frame pieces. I used a miniature hobbyist miter box and handsaw with the razor thin fine cut saw blades.

Then I cut all the larger stock lengths with a couple changes to some of the joint designs for more simplification. I decided to use pieces of the little stock to reinforce the inside of these angled corner joints.

This is the alignment of lower panels and side sections aligned with the floor.

This is the lower sections of the safety cage waiting for the glue to dry.

This is the two sides of the main frame rails clamped and waiting for the glue to dry.

This is the first fit-up of the cage lower sections and frame with shields set in place.

This is the two separable sections before I added the sheet to the front and rear of the frame shields and of course before I clean all the excess glue. I wanted to solder all the joints like my brass art works but it has to be much stronger so a two part epoxy that I can layer where needed for this full front collision test was the more logical solution and less work so crashing it wont hurt as much.

I was going to paint the cage red and frame blue and shield magenta like my drawings but figured that would hide all the work and besides I really do like the look of the brass.

I have already figured out how to use two model train wheel bogies on a track to launch this into a flexible wall because there are no crush zones in this miniature design. In the first series of tests I will use just the sled assembly to establish the base-line measurements. The second set of tests will be with the addition of the frame and cage. I have already started a couple versions of the miniature extendable cable tether assemblies.

Here it is almost finished.

Still working out options for the four tether mounts between the cage and frame, complex verses very simple. Still waiting on some parts to come in before I can finish building the rolling launch sled.

This is Strax the crash test victim.

As you can see I did not want to put in any details and that he is very stocky to withstand the crash. I made the bench seat, floor and front wall panels from one piece for simplicity and a little added strength.

I decided to go with a combination of ideas for the Tether System. With telescoping tube stock I made the Spindle removable in case I needed to change the Spool and Tether on crash day.

I used 15 Pound Braided Fishing Line. Wrapped two lengths together for theoretically 30 Pounds of Pull Force and braided the four strands together with a dab of clear nail polish.

These are the two G-Force Instruments I decided to go with. The one for the Safety Cage is perfect in range and size and weight. The Frame and Sled Black Box is perfect to use as a section of the Assembly Structure. It is certified to 50 g's and has a little headroom with measurements to 60 g's maximum.

I went with the largest model train size wheel bogie, the G-Scale, with bronze wheels and with axle springs. I went with brass track in 48 inch [1.2m] sections. I decided to go with 30 degree walls on the Track and Ramp System for the Launch Sled.

This is the Sled on the Track. As you can see the Model Mounting Plate will keep the Test Vehicle Level like the Old School Downhill Collision Tests for Jet Pilot Seats and Harnesses.

This is the Launch Sled all finished.

As you can see I used lengths of 1/16 [1.5mm] x 1 inch [25mm] galvanized steel bar, two lengths of 1 x 1 x 1/8 [25x25x3mm] steel angle and 0.016 [0.4mm] brass plate.

This is the Launch Sled from the rear.

Since all the pieces were bent in a vise with a hammer, I kept to a four corner sectional design that connects to the 50g-force meter for squaring it all in place.

Hanger: Simple Pivot Sliding Brace

Track: 16ft [4.8m] at Mountable Variations 5 to 10 Degrees

Stop: Padded Front Wall with Side Rails

Above is a photo of the Test Sled after one of the Collisions into the Stop Wall.

Below is the average readout graph of the 50G-Force Meter and Points.

Since we are looking at the deceleration, the Stop G-Force, we are most interested in the Minus Scale. The Plus Scale is the effect the Angled Track is having. It took a few test runs and even going through my first stop wall to find the best design for this Garage Built Vehicle Collision Test System.

After a few tests with just the sled I was able to fine-tune my adjustments of the angle of the 16 foot [5m] test track from 40g to 48g at 3 to 6 mph [5-10kph]. Then I attached the tethers between the cage and frame and then mounted the model onto the sled. Put it on the track and did a couple launches from a couple feet away from the wall to make sure everything was tight. Took a couple deep breathes and walked it up the track for the first of five physical tests of my design.

Below is the Average of the first 4 of 5 Collision Tests of the Cage.

This Last Test is of the Cage with some Frame Crush Zone

As you can see this graph illustrates all 3 Direction Movements of the Cage. The Total G-Force Impact is 7.4g and the Forward Impact is only 2.8g and is more Gradual Up and Down. The Sled on this specific run Measured 53.6g that figures out to be at least a 724% Improvement for the Total Impact Reduction.

This was from start to finish a very gratifying Garage Project. I was of course a little disappointed that the frame gave in at only five runs, until after I read the Data Logger Graphs. Not replacing the broken off Lower Mid Frame Shield Rails from the First Test had a lot to do with Cage being able to push over the Front Shield in the Last run. It was more important to not change any of the conditions of the assembly, to be consistent and learn how every failure point applies to the success of the collision impact absorption. I could not be more pleased with the results and as you can see for yourself this turned out to be a very Insightful Scientific Experiment for A Separable Occupant Safety Cage.

Here is the Video of the Results from these most Extreme Collision Tests
Test 1; as compared to the slow motion should demonstrate The Speed of A Impact Event
Test 3; was chosen because the Compound Offset of the hit also Simulates A Side Impact
Test 5; is a demonstration of A Collapsible Frame for A Separable Occupant Compartment

NOTE; 1/16 Scale Model Conditions:
G-Force Measurements of Mass Over Stop Distance Do Not Scale
Frame/Sled Stop Distance of 1 inch [25mm] Scales Up To 16 inch [406mm]
Compartment Cage Stop Distance of 2 inch [50mm] Scales Up To 32 inch [813mm]

RESULTS; Test #5: FRAME at 1/2 inch 54.G-F // CAGE at 2 inch 3.G-F
( G-F = Gravity Force on an object moving fast stopped very quickly )

Tether-A-Way Collision Test Video

Tether-A-Way Prototype Collision Test #5 Defined

(Link Should Start Your MP4 Player Automatically)

High-Speed
Collision Survival
Tether-A-Way Mounting Arrangement

Tether-A-Way Mounting Arrangement


In the mean time, check out the DEVCO Commuter Coupe Design

DEVCO Commuter Coupe


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