When a specialty tractor is operated by mounting the front loader or backhoes,
the loads are distributed proportionately to the front and rear axles. The
maximum load and fatigue life were identified as the main parameters in
predicting fatigue failure. This paper mainly focuses on predicting front axle
loads and fatigue life in front loader applications.
To design a new front axle for the loader application, an existing front axle
assembly that was designed for orchard, sprayer, and small farm application is
selected for study and to extend it for front loader application with minimal
design modifications. The major challenge is to estimate the dynamic loads
coming to the front axle due to the front loader application and validate it for
a different set of load cases as per the design verification plan. Hence a
methodology was framed to estimate the actual loads using MBD, validate with
field measurements, and verify the new front axle design using those loads in
FEA. This paper discusses this methodology in detail. MBD was performed on a
tractor model with an existing front axle assembly for three loader bucket
positions. The estimated static loads from MBD are validated with static field
measurement data. This estimated load was used in FEA to identify stress hotspot
location in the front axle assembly. Strain gauges were used on those hotspot
locations to find the maximum dynamic load during actual driving conditions with
the front loader application. Design modification has been done on the existing
front axle assembly and nonlinear static analysis was performed using the
maximum dynamic load to find the maximum stress location and corresponding
fatigue life. By this methodology, the existing front axle is modified,
simulated with CAE analysis, and validated with field measurement data, which
helped us to meet the design acceptance criteria as per DVP for the new front
axle design.