Present work deals with the process of determination of strain in a structural member under intense load for a typical Indian truck. Characteristics of mechanical strain at various locations on the structure are assessed. Strain gauge selection along with process of locating significant positions for strain measurement on the structure is described. Experimental process is employed for strain measurement. From the experimentation carried on the structure, the results reveal that the tri-axial stresses are dominant over bi-axial and uni-axial stresses at critical points on the structure. Contemporary data acquisition systems are utilized to acquire the strain signals. Computer simulation is carried out to have perception of the behavior of the structure under consideration. Static and Dynamic strain measurement is carried out at constant speeds on various tracks. As there are no assumptions involved in measurement like theoretical modeling and analysis, the experimental method provides the actual strain/stress values at the selected locations. Locations have been selected at cross-members where they are supported at the longitudinal members. As the stresses at these locations are not unidirectional, rosettes have been used to acquire strain in three directions. Linear strain gauges used at locations on longitudinal members.

1. International Journal of Mechanical and Production
Engineering Research and Development (IJMPERD)
ISSN 2249-6890
Vol. 3, Issue 3, Aug 2013, 83-88
© TJPRC Pvt. Ltd.
STRAIN CHARACTERISTICS IN A UNIQUE PLATFORM INTEGRATED WITH TRUCK
CHASSIS UNDER INTENSE LOAD
DEULGAONKAR VIKAS RADHAKRISHNA & MATANI ASHOK GURMUKHDAS
Mechanical Engineering, Government College of Engineering, Sant Gadge Baba Amravati University, Amravati,
Maharashtra, India
ABSTRACT
Present work deals with the process of determination of strain in a structural member under intense load for a
typical Indian truck. Characteristics of mechanical strain at various locations on the structure are assessed. Strain gauge
selection along with process of locating significant positions for strain measurement on the structure is described.
Experimental process is employed for strain measurement. From the experimentation carried on the structure, the results
reveal that the tri-axial stresses are dominant over bi-axial and uni-axial stresses at critical points on the structure.
Contemporary data acquisition systems are utilized to acquire the strain signals. Computer simulation is carried out to have
perception of the behavior of the structure under consideration. Static and Dynamic strain measurement is carried out at
constant speeds on various tracks. As there are no assumptions involved in measurement like theoretical modeling and
analysis, the experimental method provides the actual strain/stress values at the selected locations. Locations have been
selected at cross-members where they are supported at the longitudinal members. As the stresses at these locations are not
unidirectional, rosettes have been used to acquire strain in three directions. Linear strain gauges used at locations on
longitudinal members.
KEYWORDS: Strain Gauges, Degreaser, Solvants, Platform, Strain Signals
INTRODUCTION
With present emphasis on product accountability and energy competence, new anticipated designs must be lighter
and stronger, and more scrupulously tested. This places pioneering importance on the experimental stress analysis and the
strain measurement techniques. Mechanical strain is a scientific and generic term that relates to the dimensional
transformation facets in component under contemplation. Nature of strain induced in the structure on chassis relies on the
category of freight. For any nation transportation occupies a key role in economic and industrial augmentation. The
unswerving use of a road vehicle necessitates the persistent adjustment of its speed and distance in response to change in
traffic conditions. A truck/transportation vehicle is subjected to innumerable types of static and dynamic loads during its
travel. The structure under consideration is especially designed for intense load. The structure is comprised of an
amalgamation of C-Sections and tapered C-Sections. These members are termed as longitudinal and cross members of the
platform. Special arrangement is made for subjecting the platform/structure to concentrated load.
CONCEPTION OF THE SPECIALISED STRUCTURE
The excerption of individual component section and its dimension is the fundamental step in structure design.
This is accomplished using Indian Standard 808, 1989 (IS 808). Selection of materials for the components is carried using
the Indian Standard 800, 2007 (IS 800) section 2. The design process of structure is in accordance with IS 800, 2007
section 9. Determination of limit stresses is done with the presumption that combined shear and bending forces are

2. 84 Deulgaonkar Vikas Radhakrishna & Matani Ashok Gurmukhdas
prominent on the structure. The individual constituents are so oriented in a plane parallel to the chassis plane that provides
utmost amount of strength to the structure. All the longitudinal and cross members are combined using oxy-acetylene
welding process. Channels of 50x50x5 mm and appropriate length are welded at front, mid and rear portion of the
structure, in-order to offer a support to the loading plate. The locations of these plates are front, mid and rear corners of the
structure. Further these corners are identified as ISO corners at which the structure is subjected to intense load as shown in
figure.1 below. In order to enhance the stiffness of the structure, trilateral gusset plates are welded underneath the
intersection of cross and main longitudinal member.
Figure 1: Details of the Structure
STRAIN MEASUREMENT: THE EXPERIMNTATION
The preliminary step in organizing for any strain gauge installation is the selection of apposite gauge for the task.
The gauge selection process passes through various phases as evaluation of exact strain sensing alloy which decides the
operating characteristics of gauge, backing materials, gauge series, gauge length and gauge pattern. The most vital
parameter is heat dissipation and this is accounted during gage length and gage pattern selection. In the present analysis
locations have been mainly selected at cross-members where they are supported at the longitudinal members. As the
stresses at these locations are not unidirectional, rosettes have been used to acquire strain in three directions. Linear strain
gauges used at locations on longitudinal members. The loading pattern of actual loading condition has been followed while
placing the dummy load on the platform. Dynamic strain measurement has been carried out while driving the vehicle on
paved and cross-country tracks at constant speed(s). The portions of tracks have been selected such that they exhibit
approximately uniform characteristics. Dynamic measurement has been made with zero static reference. The acquired
signals have been analyzed and the dynamic components have been obtained.
Surface Preparation for Strain Gauge Installation
Prior to strain gauge installation, surface preparation for gauge installation is of supreme importance. The phases
of surface preparation are solvent degreasing, surface abrading, gauge location layout lines and surface conditioning.
Solvent degreasing eliminates oil, grease, macrobiotic impurities and soluble compound dregs. For present experiment
isopropyl alcohol is employed as degreaser. Surface abrading confiscates scale, tarnishes, paints and constructs a surface
for suitable gauge bonding. At this juncture silicon carbide paper of fine girt is utilized for surface grazing. Further gauge
location layout lines are constructed at right angles to each other with one line leaning in the direction of strain
measurement. To remove remains from burnishing operation, surface conditioning is employed. The final step is
neutralizing which brings the surface to an alkalinity of 7 to 7.5 pH, appropriate for micro-measurements. M-Prep 5A is
neutralizer in this research. Further in this research strain gauges are bonded to the structure using M-bond 200 catalyst and

3. Strain Characteristics in a Unique Platform Integrated with Truck Chassis under Intense Load 85
thereafter soldered. Extreme care is taken during soldering operation as this would disturb all the above mentioned
operations. The gauges installed and the loaded structure is shown in figure 2 below
Figure 2: Strain Rosettes and Linear Gauges at Mid and on Front of the Structure
Static measurement has been carried out for half and full design load conditions. Dynamic strain measurement has
been carried out while driving the vehicle on cross-country track at a constant speed of 20km/hr. The track portions
exhibiting approximately consistent characteristics are selected. Dynamic measurement has been made with zero static
reference. The acquired signals have been analyzed and the dynamic components have been obtained. In present strain
measurement the strain gauge locations and positions are enlisted in table 1 below.
Table 1: Strain Gauges Locations on the Structure
Rosette Locations Linear Gauge Locations
Rosette on front cross-member:
2 (RCM-2)
Left longitudinal member front
(LLM-F)
Rosette on mid cross-member:5
(RCM-5)
Left longitudinal member at
mid length (LLM-M)
Rosette on rear cross-member:
6 (RCM-6)
Left side on cross member: 5
(LCM-5)
Rosette on rear cross-member:
7 (RCM-7)
Left longitudinal member rear:
(LLM-R)
Strain Signal Acquisition and Analysis for Dynamic Load Conditions
The intensity of load acting on the structure is of crucial connotation during the vehicle in motion especially when
the vehicle travels in a rough road terrain. The probability to damage the sophisticated equipment/cargo present in the
shelter/container mounted on the structure is substantially increased due to random nature of load on cross-country tracks.
Strain signals on the novel structure for abovementioned dynamic load conditions are acquired for a truck travelling a
speed of 20kmph. The strain-acceleration signals are acquired in time domain. These strain-acceleration signals are further
analyzed using a DOS mode operating software. Root mean square (RMS) values of the signals are contrived in micro-
strain (μe). The rms values of signals measured at various locations on the structure are given in table 2 below
Table 2: Dynamic Strain RMS Values for Strain Signals on Paved Track at 15kmph
Gauge
Location
RMS (μe) Strain
Value
Gauge
Location
RMS (μe) Strain
Value
R-CM2-A (+) 37.91 R-CM5-A (+) 89.40
R-CM2-B (+) 85.98 R-CM5-B (+)255.22
R-CM2-C (+) 37.60 R-CM5-C (+) 80.50
L-LLF (-) 64.21 L-CM5 (-) 24.86
R-CM7-A (-) 9.16 R-CM6-A (+)153.55
R-CM7-B (-)28.35 R-CM6-B (+)131.22
R-CM7-C (-) 10.0 R-CM6-C (-) 65.488
L-LLR (-) 29.37 L-LLM (+) 77.55
Using the subsequent reduction technique for linear and rosette strain gauges, the dynamic values of strain are
computed. The stress values calculated based on Von-Mises criteria are tabulated below in table 3.

4. 86 Deulgaonkar Vikas Radhakrishna & Matani Ashok Gurmukhdas
Table 3: Stress Magnitudes after Analysis of RMS Strain Values
Sr.No
Gauge
Location
Stress Magnitude
(MPa)
01 R-CM: 2 17.6
02 L-LL:F -13.4
03 R-CM: 7 11
04 L-LL:R -06.1
05 R-CM: 5 54.0
06 L-CM: 5 -05.22
07 R-CM: 6 41.2
08 L-LL:M 16.2
CONCLUSIONS
The strain measurement at critical locations is carried out for the evaluation of stress to which the individual
longitudinal and cross-members are subjected, to depict the behavior of the structure due to the load applied on platform
and for the design validation of the platform. The cross-members of the platform are subjected to bending stress due to
application of the load. The behavior of the cross-members is similar to the behavior of a cantilever beam subjected to a
concentrated load applied at the free end. The magnitude of load applied is maximum at the mid portion of the platform.
From the results of strain signal analysis, it is observed that the fifth cross-member of the platform is subjected to
maximum stress of 53.8 MPa. The transfer of load to the main longitudinal member takes place through the outer
longitudinal member; cross-member and the stiffener plates present on the longitudinal and cross-member. The top (upper
surface) portion of the mid cross members of the platform is subjected to more stress.
ACKNOWLEDGEMENTS
Authors are grateful to Prof. Dr.S.P Kallurkar for his continuous and untiring support for present research work.
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