Collier Technologies

C2 Replacement Frame Testing

 

Test Report: CTR - 137

Report Date: March 27, 2006

Subject: Cycle Test Report

Part Number: C20001X1

Part Description: C2 Replacement, Full Frame Assembly, Material Stainless Steel 304, 2B Finish

 

 

Test Objective:

 

            Cycle Test a Full Frame Assembly, including Suspension and Simulated Frame Loading (Total Vehicle Weight) through 250,000 cycles and assess the durability of the Frame System.

 

 

 

General Conclusion:

         

The Test Frame survived the testing without any failures or significant deformation. This indicates that the material that the frame is constructed of has not been permanently deformed. This would then support the fact that the material (Stainless Steel 304, 2B) has not been stressed beyond its yield strength during this Cycle Test.

It should be noted that the numerous failures to the Rear Suspension System and its Fasteners can be considered indicators to the severity of this testing. The Rear Suspension System had been in use literally unchanged for 20 years and has proven itself to be a durable system. Had this suspension been deemed weak or faulty I doubt that the manufacturer would have used it for such an extended period.

 Scribe Mark Location Variations are explained lower in this report in the “Detailed Conclusions”.

 

 

 

Test Method:

 

            The Test Frame System is support on all four wheel mounting flanges, The front wheel location points, Driver Side and Passenger Side are attached to a mechanism that drives the wheels through an adjustable vertical displacement, This vertical displacement generates a force that is transmitted through the front suspension and into the frame, The displacement oscillates at 180 degrees out of phase in relation to the Driver Side and Passenger Side.

 

                          

Cycle Test Fixture with a Weighted Test Frame          Cycle Test Fixture with a Weighted Frame

(Front View)                                                          (Side View)

 

The Test Frame System is loaded with weights to simulate the total weight of the complete vehicle (Actual Total Test Weight =3508lbs. 49% on the Front, 51% on the Rear). The weights consist of 3”X3” Steel Tubing Sections welded together to form a grid. The steel tubes are filled with concrete. There are four distinct weight sections. One Mounts on the Front of the Frame using the two front (Cross-Car) mounting locations. Another one mounts on the Rear of the Frame and utilizes the two most rearward (Cross-Car) mounts. Finally two additional weight sections mount on the Forward and Rear Body Mount Locations (Fore-Aft) on Each Side Rail (Drivers Side & Passenger Side). These two weights are supported on a triangular frame that is joined together in the middle of the frame with a spring flex joint. The weight system and its supporting structure are designed to offer no to minimal additional structural support to the Frame System. The rear wheel locations are attached to skid plates that slide on a lubricated plate.

 

          

Cycle Test Fixture with a Weighted Test Frame         Cycle Test Fixture showing Vertical Displacement

(Rear Side View)                                                   (Front View)

 

 Motion of the Test Frame System is controlled with 2 forward Track Bars placed at an angle to control Fore-Aft motion as well as Cross-Car motion.  Another Track Bar was attached to the Rear Differential Bracket to control Cross-Car motion at the rear through a spring mount that allows a controlled amount of travel. The Track Bars were designed to control but not restrict motion so that the energy transmitted will pass through the Test Frame System as unobstructed as possible.

 

                 

Cycle Test Fixture Details                             Cycle Test Fixture Drive Unit

 

The Cycle Testing Fixture has a 32 horsepower electric motor with a variable speed controller driving the Main Shaft through a 6 to 1 Speed Reducer. The speed range that can be achieved is from zero to 600 Rpm. A Braking Resistor is also part of the control system. At the ends of the Main Shaft, Circular Flanges are mounted. The Crank Arms are connected to these Circular Flanges. The offset of this connection determines the stroke or vertical displacement generated by the Cycle Testing Fixture. The Crank Arms are connected to a two Urethane Pads each. Sandwiched in between the two pads are the Mounting Plates that attach to the Front Wheel Hubs. The Testing Fixture incorporates the Urethane Pads to simulate the effect that the Tires would have on the Vertical Motion applied.

Guard Railings total surround the Cycle Testing Fixture and Safety Interlocks are attached to the Frame on test that will shut the system down if excessive or uncontrolled motion of the Frame occurs.

 

 

           

Some of the Scribe Locations & One Datum Stand              Scribing & Recording Results

 

The Frame is scribed at numerous locations along the Frame Rails and Cross Members in the weighted condition while supported at 4 Datum Locations. This sets the Base Scribe Marks before the Frame is tested. The Frame is then installed onto the Cycle Testing Fixture and Cycled 250,000 times at 120rpm, with the Vertical Displacement set at a 5” stroke.  The Frame is monitored visually for any signs that permanent deformation or failure is taken place during the cycling. After cycling is completed the Frame is removed from the Cycle Test Fixture and supported on 4 Datum Location. The Frame is again scribed in the same locations as the Base Scribe Marks a comparison is then made and the results recorded.

 

 

Test Results:

 

 

10/14/05

Cycles Today: 36 000,  Accumulated Cycles: 36 000

 

            Cycle Test Fixture started at 7:30am.  Test stopped at 8:15am due to 2 Broken Bolts. These Bolts hold the Differential to the Differential Cross Member, Bolts Replaced and Test restarted at 8:45am. Test stopped at 12:00pm and restarted at 1:00pm. Stopped at 2:00pm to replace the Spring Mount on the Rear Differential Track Bar.

 

 

         

Two of the many failed fasteners.              Top View of 2 of the 4 Differential Mounting Bolts

         

 

 

10/17/05 Cycles Today: 21 600, Accumulated Cycles: 57 600

            Completed reassembly of Differential Track Bar & Spring Mount. Cycle Test restarted at 1:00pm and stopped at 4:00pm.

 

 

Rear Track Bar & Spring Mount

 

 

 

10/18/05 Cycles Today: 52 200, Accumulated Cycles: 109 800

            Cycle Test Fixture restarted at 7:30am, stopped at 11:45am due to 2 broken bolts. Again 2 of the 4 bolts that hold the Differential to the Differential Cross Member failed. These 2 bolts were on the right side of the 4 bolt pattern. The test was restarted at 1:00pm after the bolts were replaced and stopped at 4:00pm.

 

 

Differential to Differential Cross Member Mounting

Bolts Location

 

 

10/19/05 Cycles Today: 16 200, Accumulated Cycles: 126 000

            Cycle Test Fixture restarted at 7:20am, stopped at 9:35am due to 2 broken bolts. Again 2 of the 4 bolts that hold the Differential to the Differential Cross Member failed. These 2 bolts were on the right side of the 4 bolt pattern.

 

10/20/05 Cycles Today: 14 400, Accumulated Cycles: 14 0400

            Cycle Test restarted at 2:00pm and stopped at 4:00pm.

 

10/21/05 Cycles Today: 54 000, Accumulated Cycles: 194 400

          Cycle Test restarted at 7:00am and stopped at 8:00am due to a broken bolt. This bolt is 1 of 4 that hold the Leaf Spring to the Differential. The forward left bolt in the pattern of 4 bolts failed. The bolt was replaced and the Cycle Test restarted at 9:30am. The Test was stopped at 4:00pm.

         

10/24/05 Cycles Today: 2 400, Accumulated Cycles: 196 800

          Cycle Test started at 8:20am stopped at 8:40am

 

10/25/05 Cycles Today: 24 000, Accumulated Cycles: 220 800

          Cycle Test started at 8:00am stopped at 8:40am due to a broken bolt. This is again a Leaf Spring Mounting Bolt that is located in the forward left position. The bolt was replaced and the Test restarted at 11:20am. At 11:35am it was noticed that a bolt that retains the Differential to the Differential Cross Member had broken. The testing was allowed to continue until 12:00pm when a second bolt broke in the Differential to Differential Cross Member mounting area. The bolts were replaced and the Cycle Test restarted at 12:40pm. The Cycle test was again stopped when the Rear Spring failed at 2:40pm.

 

 

         

A Failed Leaf Spring                                  Leaf Spring Mounting Bolts

 

 

 

10/26/05 Cycles Today: 29 400, Accumulated Cycles: 250 200

          The Cycle Test restarted at 10:45am and stopped at 12:00pm. The Cycle Test was again restarted at 12:40pm and completed at 3:30pm

 

 

Test Ended

 

 

 

Detailed Conclusions:

 

See Table Titled “Test Scribe Mark Locations”

 

The amount of Variation identified on the Test Scribe Mark Locations (0.040” Max.) can be considered inconsequential. The material is still in its elastic range and has not taken a definite set, as no distortion is visible to the Frame Structure that could be attributed to the Variations. The positions of the Datum Supports on the Frame are on a Fore and Aft Location of each Side Rail leaves a substantial amount of structure and Simulation Weights cantilevered out away from the supports. The (4) Datum Support locations dimensions have changed from the initial values when compared to test end values due to surface/contact location between the Surface Plate and the Frame. These variations would be amplified by the distance/amount of cantilever. This would then present a possible explanation to why the Test Scribe Mark Locations have shown minimal changes.

 

 

Addendum:

 

Stainless Steel Frames

 

Collier Technologies has design, prototyped and tested a stainless steel frame to meet a demand in the market for an exotic vehicle frame that will resist corrosion.  Unfortunately many exotic cars from the 1960’s, 1970’s, and 1980’s that are otherwise in excellent condition have the frames corroded to the point where the vehicle is no longer safe to drive and can no longer pass MTO safety standards.  Therefore, we present our frame as a permanent solution to this problem.  There have been many questions as to the usability of this material and to answer those questions we have put together the following facts for your review.

 

The grade of stainless steel used by Collier Technologies for its frames is type 304.

 

This material is known for the following characteristics:

  1. Resistance to corrosion
  2. Resistance to oxidation
  3. Beauty of appearance (when polished)
  4. Ease of cleaning
  5. Higher strength is achieved with 304 type stainless steel compared with low carbon steels.
  6. Good strength and toughness at cryogenic (very low) temperatures

 

The chemical composition of this material as per ASTM A240 and ASME SA-240 is as follows.

 

Element

% by weight, maximum unless range is specified

Carbon

0.08

Manganese

2

Phosphorus

0.045

Sulphur

0.03

Silicon

0.75

Chromium

17.00 / 19.00

Nickel

8.00 / 10.00

Nitrogen

0.1

 

 

Much had been said about Stress Corrosion Cracking as it relates to Stainless Steel.

 

Conditions that cause SCC (Stress Corrosion Cracking) are as follows:

  1. presence of halide ions (generally chloride) road or sea salt.
  2. residual tensile stresses
  3. temperatures in excess of about 120° F or 49° C

 

Tests for Ambient Temperature Seacoast Exposure on a U-Bend (highly stressed samples) revealed no cracking in the base metal or as a welded sample.  Failure occurs with other types of chlorides such as Sodium Chloride and Calcium Chloride but only under conditions of high stresses and elevated temperatures (boiling Chloride solution).

 

Low Temperature Properties

 

Austenitic stainless steels have been used extensively for subzero applications to -450°F.  Yield and tensile strengths of austenitic stainless steels increase substantially as testing temperature is decreased and these steels retain good ductility and toughness at -450° F.

 

Typical short time tensile property data for minus 100°F and plus 70°F are shown below.

 

Test Temperature °F

0.2% Yield Strength PSI

Tensile Strength PSI

Elongation % in 2" or 51mm

-100°

50, 000

150, 000

50

70°

35, 000

90, 000

60

 

 

Welding

 

The austenitic stainless steels such as type 304 used by Collier Technologies are considered to be the most weldable of the high-alloy steels and can be welded by all fusion and resistance welding processes.  The two importable considerations in producing weld joints in the austenitic stainless steels are:

  1. preservation of the corrosion resistance
  2. avoidance of cracking

 

The higher the carbon level of the material being welded, the greater the likelihood that the welding thermal cycle will result in the chromium carbide precipitation which is detrimental to corrosion resistance.  Collier Technologies uses type 308L wire for welding, this enriched composition avoids martensite which might otherwise form in multipass welds.  Chemistry is controlled to allow a small amount of ferrite in the deposit to limit hot cracking.  308L is a low carbon wire, 0.04 max.

 

Durability Testing

 

Collier Technologies has conducted durability cycle testing on both the normal carbon steel frames as well as their stainless steel frames. 

 

Conclusion

 

Collier Technologies stands behind the use of their stainless steel frames in all normal driving conditions and applications based on the technical information available shown above and as shown in the durability test report.