DESC:TECHNICAL FIELD
Embodiments of the present disclosure relates to a system for suspension spring testing. More particularly, embodiments relate to the system for testing durability of leaf spring to validate leaf spring durability under combined effect of vertical load, torsional load and lateral load.

BACKGROUND OF DISCLOSURE

The typical vehicle suspension comprises two main components that are springs such as leaf springs and a damper. The suspension stores energy in the spring and dissipates energy through the damper. Both components are fixed at the design stage. The leaf spring is chosen based solely on the weight of the vehicle.. Hence testing the leaf spring in the vehicle suspension is very crucial. It is required to measure the leaf spring performance like stiffness and durability to evaluate life as per the testing requirements, in the vehicle suspension development cycle.

Customer safety is one of the major aspects for component development in automotive industry. In other words, primary suspension of heavy commercial and medium commercial vehicle is back bone of vehicle structure and also it plays major role in vehicle stability. Hence, development and validation of vehicle suspension must be performed with consideration of all failure modes that could occur on any point of time in vehicle life.

In the existing test setup, the durability testing on the leaf spring is performed by applying load on the leaf spring only in vertical direction. There is no arrangement to apply load on the leaf spring in other directions i.e. with the existing test setup the simulation of torsional loading and lateral loading is not possible. However, in the vehicles major failures are observed on mounting backstories of springs, which is not possible to simulate as brackets are not severely loaded. Further, the limitation of the conventional test set up is high set up time of the fixtures, which is more unproductive and unsafe for the operation.

In light of the foregoing discussion, it is necessary to develop an improved system for conducting durability test on the leaf springs to overcome the limitations stated above.

SUMMARY OF THE DISCLOSURE

The shortcomings of the prior art are overcome and additional advantages are provided through the provision of system and method as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, there is provided a system for testing durability of a leaf spring. The system comprises a base plate adapted to be rigidly mounted on ground; the base plate is configured to form a support surface for the system, at least one support pillar mounted on either sides of the base plate for supporting an upper support frame. An assembly for holding the leaf spring to be tested is configured on the base plate. The assembly comprises: a pair of support members spaced apart by a predetermined distance using base platform, wherein one of the pair of support members is configured as pivot end, and other support member of the pair support members is configured as a shackle end. A vertical actuation arrangement is mounted on the upper support frame for applying vertical load on the leaf spring, wherein the vertical actuation arrangement is connectable to a bottom surface of a central portion of the leaf spring. The system further comprises at least one of: a bar provided substantially perpendicular to the base platform of the assembly for holding the leaf spring for applying torsional load on the leaf spring, wherein said bar comprises a slot of predetermined shape for accommodating the leaf spring; and a lateral actuation arrangement connectable to at least one side surface of the central portion of the leaf spring for applying lateral load on the leaf spring.

In an embodiment of the present disclosure, the vertical actuation arrangement comprises an anchor plate connected to the bottom surface of the central portion of the leaf spring, and an actuator for applying the vertical load on the leaf spring through the anchor plate. Further, a roller bearing is provided in the anchor plate of the vertical actuation arrangement.

In an embodiment of the present disclosure, at least one actuator is provided on either ends of the bar for regulating the movement of the bar to apply torsional load on the leaf spring.

In an embodiment of the present disclosure, the lateral actuation arrangement comprises an anchor plate connected to the side surface of the central portion of the leaf spring, and an actuator for applying the lateral load on the leaf spring through the anchor plate. Further, anchor plate is connected to the central portion of the leaf spring through the universal joint.

In an embodiment of the present disclosure, a control unit interfaced with the actuators of vertical actuation arrangement and the lateral actuation arrangement, and with the actuators provided on either ends of the bar for selectively actuating the actuators.

Another embodiment of the present disclosure, a method for conducting durability test on leaf spring. The method comprising acts of mounting the leaf spring on an assembly for holding the leaf spring configured on the base plate, said assembly comprises: a pair of support members spaced apart by a predetermined distance by a base platform, wherein one of the pair of support members is configured as pivot end, and other support member is configured as shackle end. Then, applying vertical load on a bottom surface of a central portion of leaf spring using a vertical actuator arrangement. The method further comprises selectively performing at least one act of: applying a torsion load on a top surface of the central portion of the leaf spring by mounting a bar substantially perpendicular to a base platform of the assembly for holding the leaf spring using actuators provided on either ends of the bar; and applying a lateral load on at least one side surface of the central portion of leaf spring using a lateral actuation arrangement.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

OBJECTIVES OF THE DISCLOSURE

One object of the present disclosure is to provide a system for conducting durability on the leaf spring under the influence of vertical load and torsional load.

One object of the present disclosure is to provide a system for conducting durability on the leaf spring under the influence of vertical load and lateral load.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG. 1 illustrates the schematic diagram of the vertical load, lateral load and torsional loads exerted on vehicle suspension.

FIG. 2 illustrates a perspective view of a system configured for conducting durability test on leaf spring according to the present disclosure with an arrangement to apply vertical load on the leaf spring.

FIGS. 3a and 3b illustrates a perspective view and sectional view of a system respectively for conducting durability test on leaf spring according to the present disclosure with an arrangement to apply combination of vertical load and torsional load on the leaf spring.

FIG. 4 illustrates a perspective view of a system for conducting durability test on leaf spring according to the present disclosure with an arrangement to apply combination of vertical load and lateral load on the leaf spring.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

To overcome the drawbacks mentioned in the background, the present disclosure provides a testing system for validating vehicle suspension system. The system of the present disclosure applies combination of vertical load and torsional load, and combination of vertical load and lateral load in simultaneous manner and compiles test parameters for further virtual testing and multi body dynamic analysis. A test methodology is disclosed in the present disclosure which could simulate all possible modes which will occur during dynamic running of vehicle. With the test system of the present disclosure the durability of leaf spring at test rig level is conducted with exact replication of all dynamic loads of the vehicle.

FIG. 1 is an exemplary embodiment of the present disclosure which illustrates the schematic diagram of the vertical load, lateral load and torsional loads exerted on vehicle suspension (1). The vehicle suspension (1) undergoes tremendous/harsh environment when they are subjected to vertical and lateral loads. Further, it is evident from the failure modes and design aspect of the vehicle suspension (1) that the vertical loading on one side of wheel (3) induces heavy torsional loads on the other side of wheel (3). This is applicable to rigid axle suspension system only. Whenever tire (3) goes for a bump it stimulates axle to move around its roll axis i.e. (4) of axle. During which other side of leaf spring undergoes torsion and lateral loads together. If it is resolved at each individual wheel (3), it can be seen that around each spring it rotates and moment around longitudinal axis is generated. Hence, more often failure modes such as spring sizzering, spring pivot end failure, suspension bush failure and center bolt misalignment is caused not only because of vertical loads but also due to torsion and lateral loads. Further, the torsion load on the leaf spring is more during high speed lane change, side kerb strike and hilly road cornering generates lateral loads on the vehicle (2).

To test the leaf spring also referred as suspension system as per dynamic loading conditions it is necessary to simulate the vertical load, lateral load, and torsional load in any point of time during dynamic testing of the leaf spring.

FIG. 2 is an exemplary embodiment of the present disclosure which illustrates a perspective view of a system (100) for conducting durability test on leaf spring (101) with an arrangement to apply vertical load on the leaf spring (101). The system (100) comprises a base plate (102) of predetermined shape rigidly mounted on ground. The base plate (102) is configured to form a support surface for the system (100). At least one support pillar (103a ad 103b) is mounted on either sides of the base plate (101) for supporting an upper support frame (104). The upper support frame is joined to the support pillars (103a and 103b) through fasteners. The support pillars (103a and 103b) are provided with the plurality of mounting holes on their inner surface for joining the upper support frame at required height. The support pillars (103a and 103b) along with the upper support frame (104) forms H-shaped structure on the base plate (102). Further, an assembly (105) for holding the leaf spring (101) to be tested is configured on the base plate (102). The assembly (105) comprises a pair of support members (105a and 105b) spaced apart by a predetermined distance using a base platform (105c). The support member (105a) of the pair support members is configured as pivot end, and the support member (105b) of the pair support members is configured as a shackle end for holding the leaf spring (101) to be tested. The provision of pivot end and the shackle end in the testing assembly help to simulate the exact connecting condition of the leaf spring (101) in the vehicle. Further, as shown in FIG. 2 a vertical actuation arrangement (106) is mounted on the upper support frame (104) for applying vertical load on the leaf spring (101) during testing. The vertical actuation arrangement (106) is connectable to a bottom surface (101a) of a central portion (C) of the leaf spring (101). The vertical actuation arrangement (106) comprises an anchor plate (106a) connected to the bottom surface (101a) of the central portion (C), and an actuator (106b) connected to the anchor plate (106a) for applying the vertical load on the leaf spring (101) through the anchor plate (106a).

FIGS. 3a and 3b are exemplary embodiment of the present disclosure illustrating a perspective view and sectional view of a system for conducting durability test on leaf spring with an arrangement to apply vertical load and torsional load on the leaf spring. As shown in FIG. 3a the leaf spring (101) is mounted in the assembly (105) for holding the leaf spring. Then, to apply torsional load onto the leaf spring (101) a bar (107) is provided substantially perpendicular to the base platform (105c) of the assembly (105) for holding the leaf spring (101). The bar (107) comprises a slot of predetermined shape for accommodating the leaf spring (101). The bar (107) is mounted to the top surface (101b) of the center portion (C) of the leaf spring (101), along with the anchor plate (106a) using “U” bolt as shown in FIG. 3b. Further, at least one actuator (108) is provided on either ends (107a and 107b) of the bar (107) for regulating the movement of the bar to apply torsional load on the leaf spring (101). The vertical actuation assembly (106) [best shown in FIG. 2] is mounted in the system (100) to apply vertical load on to the leaf spring (101) simultaneously with the torsional load.

To apply the vertical load and the torsional load onto the leaf spring (101), a vertical actuator (106b) is pushed down to apply vertical load on the leaf spring (101) through the anchor plate (106a). Further, a roller bearing (106c) is provided in the anchor plate (106a) to facilitate torsional movement to the leaf spring (101) by eliminating the lateral and vertical movement. Upon application of vertical load the leaf springs (101) flatten its axis, on the same time torsion movement is engaged by pulling and pushing the bar (107) up and down through actuators (108). At this condition, the leaf spring (101) will try to rotate at its axis. During this phenomenon the roller bearing (106c) will rotate around axis and will move around the center (C) of leaf spring (101) as there is constraint provided at circumference of roller bearing (106c) to roll axis. This mechanism ensures both vertical and torsion loads simultaneous application on the leaf spring (101).

During dynamic testing it is observed that lateral loads are active on wheel (3) of the vehicle (2) but with low frequency of vertical loads. During high speed lane change or steady state circular trial, the wheel (3) undergoes constant vertical load and then lateral loads which are applied on to a wheel (2) in turn on suspension. Hence, it is necessary to simulate the constant vertical load and then application of cyclic lateral loads on the leaf spring (101).

FIG. 4 is an exemplary embodiment of the present disclosure which illustrates a perspective view of a system (100) for conducting durability test on leaf spring with an arrangement to apply vertical load and lateral load on the leaf spring (101). To apply the lateral load on the leaf spring (101) a lateral actuation arrangement (109) is connected to at least one side surface (101c) of the central portion (C) of the leaf spring (101). The lateral actuation arrangement (109) comprises an anchor plate (109a) connected to the side surface (101c) of the central portion (C) of the leaf spring (101). In an embodiment of the present disclosure, the anchor plate is connected to the central portion of the leaf spring (101) through the universal joint i.e. U-J- joint. Further, an actuator (109b) is connected to the anchor plate (109a) for pulling and pushing the anchor plate (109a) for applying the lateral load on the leaf spring (101). The vertical actuation assembly (106) [best shown in FIG. 2] is mounted in the system (100) to apply vertical load on to the leaf spring (101) simultaneously with the lateral load. A half circle is provided at lateral actuator (109b) to ensure the corrective action, during vertical loading and lateral cyclic loading. The half circle can be made of a material selected from at least one of synthetic rubber or metallic bush.

To apply the vertical load and the lateral load onto the leaf spring (101), a vertical actuator (106b) is pushed down to apply vertical load on the leaf spring (101) through the anchor plate (106a). Upon application of vertical load the leaf springs (101) flatten its axis, on the same time lateral movement is engaged by pulling and pushing the anchor plate (109a) to and fro through actuators (109b). At this condition, the leaf spring (101) will try move to and fro. This mechanism ensures both vertical and lateral loads simultaneous application on the leaf spring (101).

The system (100) of the present disclosure is complete mechanical adaptation for simulation and testing of complete spring. Using the mechanical adaptation as stated above suspension parameters of the leaf spring (101) can be simulated and can be tested with simultaneous loading option on system (100).

In an embodiment of the present disclosure, there is provided an accelerated test methodology of the leaf spring for its durability. To conduct the accelerated durability test on the leaf springs the vertical actuator (106b), lateral actuators (109b), and torsional actuators (108) are interfaced to a control unit. The control unit will be loaded with the predetermined data taken from the vehicle during its working cycle, for conducting the durability test at the test rig level. The accelerated test methodology includes following acts:
a. Road inputs and real time usage capturing using sensors and data acquisition system;
b. Conversion of displacement and wheel forces into Vertical, Torsional and lateral load joint distribution for combined and weighted damage calculation; and
c. Simulation of simultaneous loads and accelerated test schedule for vehicle life cycle testing.
Each of these steps are explained in detail herein below:
a. Road inputs and real time usage capturing using sensors and data acquisition system;
Since, wheel forces and moments can be directly captured using wheel force transducers, it is easy to install and get real time simultaneous loads across left hand side and right hand wheels. However, with the use of wheel displacement sensors the vertical movement and the torsional movement can be resolved. Here, vertical actuator of one of the wheels acts as torsional movement simulator for another wheel.

To capture the damage of these loads, strain gauges are applied to leaf spring at various locations to measure vertical direction related stress and torsional stress. By these strain gauges, damage accumulation can be derived and loads can be converted into real damage which could be used to accelerate the test cycle in terms of time.

b. Conversion of displacement and wheel forces into Vertical, Torsional and lateral load joint distribution for combined and weighted damage calculation.
Based on joint load distribution only damaging real time peaks can be extracted from time signal and it can be converted using joint probability distribution function of durability analysis software. This will help in deriving block loading cycles on individual leaf springs. Multi axis loading can be derived using standard analysis functions and hence are not covered in totality. Life cycle time series data containing left hand side and right hand side wheel displacement and wheel forces will be converted into joint or simultaneous multi axis loads to simulate damaging cycles on spring and hence acceleration can be achieved.

c. Simulation of simultaneous loads and accelerated test schedule for vehicle life cycle testing.
The total accumulated data of captured signal for 1 durability test circuit and its damage is comparable to 100 km of service equivalence. If the data is converted in to test schedule of 100 km, and if the life of vehicle is 1, 00,000 km; the test needs to repeat 1000 times to cover up entire life cycle. Similar methodology can be applied for vertical and lateral loads and combined cycle can be formed including equal distribution of vertical v/s torsional actuation and vertical v/s lateral load simulation. After each repeats of 10 torsional cycles, test can be repeated for 10 cycles of lateral loads and hence correlation with service failures also can be achieved.

In the accelerated test methodology, actual wheel displacement of left hand side and right hand side wheels is measured on durability tracks which are representative of service usage pattern and then test specifications are derived for following three modes, i.e. only vertical motion of spring, vertical and torsion mode, Vertical and lateral modes. Then the number of cycles is equated to actual life cycle of the springs, and springs are tested till its life time. By performing such testing life cycle validation can be performed within 7-8 days. In actual it would take months together to test the life cycle/durability of the leaf springs on tracks.

Advantages:

The present disclosure provides system for conducting durability test on leaf springs, which performs two types of tests, i.e. it facilitates to evaluate the damper life under the influence of vertical and torsional loads, and vertical load and lateral load. Therefore, the durability of the suspension damper can be evaluated under all possible loading/working conditions of the leaf springs.

The present disclosure provides system for conducting durability test on leaf spring which is compact, easy to mount and dismount on the existing servo-hydraulic damper test rig and cost effective.

The present disclosure provides system for conducting durability test on leaf spring which is simple in construction and easy to assemble, which provides good serviceability and maintainability.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Referral Numerals;

Reference Number Description
100 System for conducting durability test on leaf spring
101 Leaf spring
101a Bottom surface of leaf spring
101b Top surface of the leaf spring
101c Side surface of the leaf spring
C Centre of the leaf spring
102 Base plate
103a and 103b Support pillars
104 Upper mounting frame
105 Assembly for holding the leaf spring
105a Pivot end
105b Shackle end
105c Base platform
106 Vertical actuation arrangement
106a Anchor plate of vertical actuation arrangement
106b Actuator of vertical actuation arrangement
107 Bar
107a and 107b End of bar
108 Actuators mounted on bar
109 Lateral actuation arrangement
109a Anchor plate of lateral actuation arrangement
109b Actuator of lateral actuation arrangement
1 Vehicle suspension
2 Vehicle
3 Tires
4 Axle roll axis
5 Spring roll axis
,CLAIMS:1. A system for testing durability of a leaf spring, said system comprises:
a base plate adapted to be rigidly mounted on ground, the base plate is configured to form a support surface for the system;
at least one support pillar mounted on either sides of the base plate for supporting an upper support frame;
an assembly for holding the leaf spring to be tested is configured on the base plate, said assembly comprises: a pair of support members spaced apart by a predetermined distance using base platform, wherein one of the pair of support members is configured as pivot end, and other support member of the pair support members is configured as a shackle end;
a vertical actuation arrangement mounted on the upper support frame for applying vertical load on the leaf spring, wherein the vertical actuation arrangement is connectable to a bottom surface of a central portion of the leaf spring; and
at least one of:
a bar is provided substantially perpendicular to the base platform of the assembly for holding the leaf spring for applying torsional load on the leaf spring, wherein said bar comprises a slot of predetermined shape for accommodating the leaf spring; and
a lateral actuation arrangement connectable to at least one side surface of the central portion of the leaf spring for applying lateral load on the leaf spring.

2. The system as claimed in claim 1, wherein the vertical actuation arrangement comprises an anchor plate connected to the bottom surface of the central portion of the leaf spring, and an actuator for applying the vertical load on the leaf spring through the anchor plate.

3. The system as claimed in claim 2 comprises a roller bearing provided in the anchor plate of the vertical actuation arrangement.

4. The system as claimed in claim 1, wherein at least one actuator is provided on either ends of the bar for regulating the movement of the bar to apply torsional load on the leaf spring.

5. The system as claimed in claim 1, wherein the lateral actuation arrangement comprises an anchor plate connected to the side surface of the central portion of the leaf spring, and an actuator for applying the lateral load on the leaf spring through the anchor plate.

6. The system as claimed in claim 5, wherein the anchor plate is connected to the central portion of the leaf spring through the universal joint.

7. The system as claimed in claim 1 comprises a control unit interfaced with the actuators of vertical actuation arrangement and the lateral actuation arrangement, and with the actuators provided on either ends of the bar for selectively actuating the actuators.

8. A method for conducting durability test on leaf spring, said method comprising acts of:
mounting the leaf spring on an assembly for holding the leaf spring configured on the base plate, said assembly comprises: a pair of support members spaced apart by a predetermined distance by a base platform, wherein one of the pair of support members is configured as pivot end, and other support member is configured as shackle end;
applying vertical load on a bottom surface of a central portion of leaf spring using a vertical actuator arrangement; and
selectively performing at least one act of:
applying a torsion load on a top surface of the central portion of the leaf spring by mounting a bar substantially perpendicular to a base platform of the assembly for holding the leaf spring using actuators provided on either ends of the bar; and
applying a lateral load on at least one side surface of the central portion of leaf spring using a lateral actuation arrangement.