FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Apparatus For Full Frame Fatigue Testing Of Vehicles


at

APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Dwivedi Vivek, Mr. Santosh Gosavi
Mr. Chimad Mahavir, Mr. Mithun Chaskar
Mr. Pradeep Mamgain, Mr. Ganesh Kale
and Mr. Shrikrishna Joshi
All Indian Nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF INVENTION
This invention generally relates to the apparatus for testing the vehicles and more particularly it relates to apparatus for Full Frame Fatigue testing of vehicles.
BACK GROUND OF THE INVENTION
Frame is the back bone of a vehicle. A frame of a vehicle should withstand predetermined period of service life, for example: 1 Million Kilometers. Hence it is necessary to validate the life span of the frame with intended loading on service road to meet the said requirement.
Generally two kind of accelerated testing methodology is available for validating the frame of the vehicles. In one kind of methodology, the test vehicle is made to run on torture track using derived torture track pattern. This kind of Test of running the vehicles in torture track takes at least 3 years to validate a Frame of vehicle for predetermined period of service life for example: 1 Million Kms. second kind of methodology is by using the six poster simulator for testing the frame of the vehicles. The six poster simulator method is used for generating fairly higher acceleration levels, but six poster testing simulates only vertical wheel loads, which in turn simulates 50 to 60 % damage on frame of the vehicles and other structural aggregates.
The six poster testing method of the vehicle requires a completely built vehicle which is held on six posters in the form of fixtures having provision to hold the wheels and to apply the forces only in the vertical direction by means of actuators. The Dead Load is put in the Load body and the vertical excitation is given at each wheel. So it is required to build the complete vehicle with Load body for six poster testing.

This setup becomes quite bulky especially for tractor trailer kind of vehicles. So an alternate setup is required to validate the frame of vehicles with higher acceleration and fairly accurate damage simulation.
This can be achieved using damage editing for acceleration and applying all kinds of Load at each wheel end for accurate response simulation. It is also possible to simulate the other structural aggregates which are in the Chassis Load path such as - Wheel ends, Axles, springs and Load body connections. To simulate the inertial effects of heavy overhung masses on frame, the same aggregates can also be attached on frame of vehicle during the testing.
Hence new apparatus is devised to load the chassis frame without using Load body or trailer to reduce the overall size of test setup. Also, Instead of using the dead load in the Load body, the chassis is restrained in vertical directions and the load is applied through each wheel to create similar effect of Loading on chassis.
Hence the efforts are put to develop the test methodology which overcomes the above mentioned disadvantages of the prior 6 posters / torture track set up for accelerated fatigue testing of the chassis frame of a vehicle.
Whatever data captured on the torture tracks; if it is directly simulated on the test rig then it might take same time as if the vehicle requires to run on torture tracks. Also time required to complete the test will be very high. But with help of fatigue editing technology we can reduce the time stamp information from the original data and test time can be compressed.
In provided time series, there is very less damaging cycles. Normally strain inputs are amplified and non damaging portion is removed keeping 90% of damage retained and removing 70% of time.

OBJECT OF INVENTION
The main object of the present invention is to provide an apparatus for full chassis frame fatigue testing of vehicles.
Another object of the present invention is to provide an apparatus for full chassis frame fatigue testing of vehicles which gives /attain up to 90% accurate damage on chassis frame.
Yet another object of the present invention is to provide an apparatus for full chassis frame fatigue testing of vehicles which validate the chassis frame of a vehicle in a comparatively very small period of time.
Still another object of the present invention is to provide an apparatus for full chassis frame fatigue testing of vehicles which provides the testing environment with less testing space requirements and easy handling.
BRIEF DESCRIPTION OF INVENTION
In accordance with the present invention an structure for Full chassis Frame Fatigue Testing for vehicles comprises Adopters in the form of fixtures to hold wheel sets of the frame assembly to be tested with specified aggregates assembled and plurality of actuators to apply loads in all the three dimensional directions (Longitudinal, Vertical, Lateral) on the said frame.
Said actuators include vertical loading actuators to apply the load in vertical direction, longitudinal loading actuators to apply the load in longitudinal direction, lateral loading actuators to apply the load in lateral direction, braking load actuators to apply the braking load and cab CG mounting actuators to apply the CAB CG load

Wherein said adopter is configured to hold said vertical loading and longitudinal loading actuators for applying force in vertical and longitudinal direction on the said frame.
Said lateral loading actuators are connected to the adopter at any one end of each axle of the frame to apply the lateral directional forces on the frame. Said Brake loading actuators are attached to the centre point of each axle to apply the braking forces on the frame. Said CAB CG loading actuators are connected to the CAB suspension brackets mounted on the said frame assembly to be tested.
Restrainers are provided on the fifth wheel coupling assembly, to restrain said frame assembly during testing. The said plurality of actuators are connected with the said adaptor through the spherical joints provided therein.
Heavy chassis aggregates are also mounted on the chassis during this test to produce inertial effects on said Frame assembly. Engine assembly along with Gearbox (Power Train) & Fuel tanks are mounted for this purpose.
BRIEF DESCRIPTION OF DRAWINGS
Figure-01 schematic view of the assembly showing the directional forces. Figure-02 top view of an axle of the assembly showing the positions of actuators. Figure-03 schematic view of the assembly showing the positions of actuators. Figure-04 schematic view of the assembly showing the position CAB CG actuator. Figure-05 schematic views showing restrainers' arrangement and restrain forces.

DETAILED DESCRIPTION OF INVENTION
Referring to the drawing, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
Now Referring to figure -01 to 05, In accordance with the present invention an Architecture for Full chassis Frame Fatigue Testing for vehicles comprises Adopters (1) in the form of fixtures to hold wheel sets (2) of the frame assembly to be tested (10) and plurality of actuators to apply loads in all the three dimensional directions (Longitudinal(X), Vertical (Z), Lateral(Y)) and other load factors such braking loads and CAB CG loads on the said frame assembly to be tested (10).
Said actuators include vertical (Z) loading actuators (3) to apply the load in vertical (Z) direction, longitudinal (X) loading actuators (4) to apply the load in longitudinal (X) direction, lateral (Y) loading actuators (5) to apply the load in lateral (y) direction, braking load actuators (6) to apply the braking load and cab CG mounting actuators (7) to apply the CAB CG load.
Wherein said adopter (1) is configured to hold said vertical (Z) loading (3) and longitudinal (X) loading (4) actuators for applying force in vertical (Z) and longitudinal (X) directions on the said frame assembly to be tested (10).
Said lateral (Y) loading actuators (5) are connected to the adopter (1) at any one end of each axle (13) of the frame (10) to apply the lateral (Y) directional forces on the frame. Said Brake loading actuators (6) are attached to the centre point of each axle (13) to apply the braking forces on the frame. Said CAB CG loading

actuators (7) are connected to the CAB suspension brackets (12) mounted on the
said frame assembly to be tested (10).
Restrainers (8) are provided on the fifth wheel coupling assembly (9), to restrain
said frame assembly (10) during testing. The said plurality of actuators are
connected with the said adaptor (1) through the spherical joints (11) provided
therein.
Heavy chassis aggregates are also mounted on the chassis during this test to produce inertial effects on said Frame assembly (10). Engine assembly along with Gearbox (Power Train) (14) & Fuel tanks (15) are mounted for this purpose. Said adopters (1) will hold the said wheel sets (2) of said frame assembly (10) there by holds said complete frame assembly (10) to be tested.
In accordance with this invention, validation of Frame of the vehicle is carried out by applying the load and other forces on said frame assembly (10) in all the three directions (Lateral, Vertical, Longitudinal), by means of said Longitudinal (X) (4), vertical (Z) (3) and lateral (5) loading actuators and to acquire the resultant forces exactly as a vehicle will experience on the torture tracks. These resultant forces are verified by means of the strain gauges pasted on the expected critical locations on the frame.
More particularly, the load is applied at each wheel end using specific actuators. Said vertical (z) actuator (3) and longitudinal (X) actuator (4) are provided at each wheel center to apply vertical & longitudinal (X) loads. Said Lateral (Y) loading actuator (5) provided per axle to apply lateral load again at wheel center. Also the braking load is applied at tyre contact patch using said braking load actuator (6) per axle (13). The requirement of no. of actuators is worked out based on the load pattern & its phase difference.

The Load drive file to be applied at each wheel end to achieve the actual running of vehicle on service road or the acceleration factor is acquired during Field running of the vehicle using Wheel force transducers, displacement sensors and strain gauges on different aggregates. Simultaneously the stress levels on the frame components is captured using strain gauge rosettes pasted at all predicted critical locations.
The chassis frame is restrained at the Load body CG location for rigid vehicles or at fifth wheel point for tractor trailer vehicles by means of said restrainers (8). This generates reaction forces at restrain point. Also this architecture imposes the same kind of loading on frame as in actual vehicle. This is cross checked using the strain gauge reading on the chassis components, which are called as response channels.
In this new setup, only the frame assembly is required, thus the test setup occupies less space when compared to the prior setup of 6 posters for chassis frame validation. Since in this new setup only actuators and restrainers are provided instead of dead weights to apply the load. This makes the setup comparatively easy to handle. Apart from the aggregates (like axle, spring, frame, load body structure) in the load path, heavy chassis aggregates such as said Engine assembly along with Gearbox (power train) (14) and Fuel tanks (15) are also mounted on the frame assembly (10) during this test to produce inertial effects.
The drive file for the test setup is created using all the wheel loads and response gauges. All these response channels are taken as control channels to enhance the accuracy of setup. The drive file also takes care of consequential effect of one load on another & its compensation.

This new setup of Full Frame Fatigue testing will require comparatively very less stretch of time to validate a chassis frame of any vehicle model. Also in this new setup we can acquire up to 90% of accuracy, since equivalent forces are applied in all the three directions (Lateral, Longitudinal, Vertical) and as well as the Braking forces direction.
Apparatus for testing the full frame of a vehicle on test rig involves simulation of the wheel input parameters like force and displacements measured by running the vehicle on the torture tracks. In addition to simulation of wheel inputs, the appropriate reactions at restraint points i.e. Cabin center of gravity and fifth wheel king pin are controlled in order to achieve the same chassis damage as it would have been observed on the torture track.
Vehicle Instrumentation
As described in the test setup that 19 actuators are used to test the full frame on test rig. Each actuator needs at least one response channel to simulate the wheel inputs.
Said all vertical actuators (3) are controlled by wheel vertical displacements. Said all Lateral (5) and longitudinal (4) actuators are controlled by respective forces and said braking actuators (6) are controlled by force and moments. The cab CG mounting actuator (7) is controlled by vertical force measured at cabin mount. The inputs applied at the wheel center are reacted by restraints applied at cabin center of gravity and fifth wheel king pin
Test methodology
1) Vehicle instrumentation and pre-processing:

a. Fitment of wheel to body displacement sensors and wheel force
transducers on wheel, strain gauges on frame for data acquisition.
b. Generating the force and displacement drive file on rough roads and
durability tracks. This exercise is required to generate force and
displacement drive file for test rig actuators.
c. Verifying the measured data and basic drive file.
2) Test rig updation and component fitment with adaptors:
a. Fitment of test frame with axle to the actuators.
b. Verification of actuator capacity depending upon the frame end
limits and actual forces experienced while track running.
c. Validating test rig actuation for three-dimensional movements
without any interference of aggregates with actuators.
3) Simulation and post-processing:
a. Simulating displacements and forces as per drive file on the test rig.
b. Calculating fatigue damage using rain-flow analysis and arriving at
maximum damaging inputs for reducing the overall test time.
c. Revalidating the fatigue edited drive file on test rig.
4) Durability running and life cycle testing:
a. Simulating the final drive file repetitively on test rig to achieve the
acceleration factor of 5-8 for reducing the time.
b. Achieving more than 90% damage retention with at least 70-80% of
time reduction.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those

skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

WE CLAIM
1) A full chassis frame fatigue testing apparatus for vehicles comprising:
wheel sets holding fixtures;
aggregates assembled on the frame assembly to be tested;
plurality of actuators to apply equivalent loads in longitudinal, vertical and lateral directions on the said frame;
braking load actuators attached to each axle to apply the braking forces on the frame;
cabin mounting actuator to apply the cab mount load; wherein said wheel sets holding fixtures are configured to hold said vertical loading and longitudinal loading actuators, said lateral loading actuators are connected to the fixtures at any one end of each axle of the frame and said brake loading actuators are attached to the centre point of each axle; and
restrainers provided to restrain said frame assembly during testing.
2) The apparatus as claimed in Claim 1, wherein said vertical, longitudinal and lateral actuators are connected with the said fixtures through spherical joints provided therein.
3) The apparatus as claimed in claim 1, wherein said aggregates assembled on the frame assembly includes engine assembly along with gear box and fuel tanks which are mounted for providing inertial effects on the said frame assembly.
4) The apparatus as claimed in Claim 1, wherein said restrainers are provided at restraint point to restrain the chassis frame.
5) The apparatus as claimed in Claim 1 and 4, wherein said restraint point are at cabin center of gravity and fifth wheel king pin.

6) The apparatus as claimed in Claim 1, wherein wheel loads and response gauges are adapted to create a drive file for the test setup taking all the response channels as control channels to enhance the accuracy.
7) The apparatus as claimed in Claim 1 and 5, wherein cabin centre of gravity and fifth wheel king pin are configured to control appropriate reactions to achieve the same chassis damage as it is observed on the torture track.
8) The apparatus as claimed in Claim 1, wherein said apparatus comprises at least 19 actuators, each actuator comprising at least one response channel to simulate the wheel inputs, said vertical actuators are controlled by wheel vertical displacements, lateral and longitudinal actuators are controlled by respective forces and braking actuators are controlled by force and moments and said cab center of gravity mounting actuator is controlled by vertical force measured at cabin mount in such a way that the inputs applied at the wheel center are reacted by restraints applied at cabin center of gravity and fifth wheel king pin.
9) A method of fatigue testing a full chassis frame comprising the steps of:
fitting of body displacement sensors and wheel force transducers on wheel,
strain gauges on frame for data acquisition and test frame with axle to the actuators;
generating the force and displacement drive file on rough roads and durability tracks;
verifying the measured data and basic drive file;
verification of actuator capacity depending upon the frame end limits and actual forces experienced while track running;
validating test rig actuation for three-dimensional movements without any interference of aggregates with actuators;
simulating displacements and forces as per drive file on the test rig;

calculating fatigue damage and arriving at maximum damaging inputs for reducing the overall test time; and
revalidating the fatigue edited drive file on test rig.
10. The method as claimed in claim 8, wherein the final drive file is repetitively simulated to achieve an acceleration factor of 5-8.
11. A Full chassis Frame Fatigue Testing apparatus for vehicles as claimed in Claim 1-8 above, largely as described in the descriptions and as illustrated in the accompanying figures.
Dated this 3rd day of October 2008