This document discusses the kinematic and structural simulation of an automated lift used in garbage collection trucks. The simulation aimed to address field failures of the lift's C-frame. Kinematic simulation identified worst case loading scenarios. Structural analysis of the baseline model matched stress patterns to known crack locations. A modified model with increased plate thickness showed reduced stresses. The accurate modeling and simulation helped validate an improved field fix design and reduce stresses by 15-35% compared to the baseline.

1. Kinematic & Structural Simulation of the Automated Lift
Vijaykumar Vaka Chinababu Anima Rajesh Kandula
Project manager Senior Design Engineer Team Lead
Infotech Enterprises Pvt.Ltd Infotech Enterprises Pvt.Ltd Infotech Enterprises Pvt.Ltd
Hyderabad-500032 Hyderabad-500032 Hyderabad-500032
Ramanadh V.V Dr.Satish. Y
Head of Engineering Deputy General Manager
Infotech Enterprises Pvt.Ltd Infotech Enterprises Pvt.Ltd
Keywords : Motion solve, Kinematic simulation, C-Frame, Automated lift
Abstract
This paper addresses the field failure problem of Automated lift (i.e., Automated lift is a part of garbage collecting unit truck). During
the operation, it has been observed, there was failure in C-Frame which needs to be addressed. The machine experience severe
dynamic forces by virtue of its continues operation, as a first step of solution, accurate load estimation is inevitable The accurate
mathematical modeling of the system achieved , with the help of operational video animation files. Kinematic simulation is carried
out in HYPERWORKS and the dynamic forces are assessed in all the components of the machine.
Kinematic simulation was created with all parts considered as rigid bodies except for the C-frame. The C-frame was modeled as a
flexbody so that dynamic stresses could be seen in the kinematic results.
C-frame stress results from the kinematic model were reviewed and moments in time at which the C-frame stresses peaked were
noted. These peak-stress events in the motion were used as time instances from which to pull joint/interface forces and moments to
apply to the C-frame FEA model. The joint forces and reaction forces were extracted for following load cases.1)Dump unit next to
the truck 2)Dump unit at maximum reach extension
Structural analysis (FEA) for the baseline model was carried out using worst case loading identified from kinematic simulation. FEA
results for the baseline were reviewed and stress patterns and load paths were observed to match well with crack locations for in-
service units. Field fix-geometry was designed and added to the baseline FEA model. The side plates were also increased in
thickness from ¼” to 5/16”.Structural analysis for the modified model was carried out using worst case loading identified from
kinematic simulation. The stresses were compared against the baseline and modified model at all critical locations.
Introduction
The automated side loader enables the driver/operator to pick up a bin that is up to 2 to 4 meters from the
body, empty the bin into the hopper and place the bin back in position without leaving the cab. The
mechanisms for lift and discharge the small pre-collecting containers on the receiving hoppers of the
refuse machines are, usually, articulated bar mechanisms. The role of those mechanisms is to lift the pre-
collecting container in vertical position, up to the feeding hopper of the refuse machine, thus the wastes
stay in the container, and then to fold it thus the waste will fall in the machine feed hopper. They are,
generally, planar mechanisms with articulated bars drive by hydraulic cylinders.
Customer has experienced premature field issues with C-Frame Automated lift mechanism. Design
improvements were implemented with improved customer satisfaction, however concern areas still
remain. The goal of this project is to analyze the complete lift structure and address concern areas.
Fig.1: Side loaded truck( Picture courtesy of HEIL )
Simulation Driven Innovation 1

2. Process Methodology (details with figures)
• Reviewed provided video files and analyzed timing to create motion curves for kinematic model for dump
at max extension and dump next to truck motions.
• Kinematic simulation was created with all parts considered as rigid bodies except for the c-frame. The c-
frame was modeled as a flexbody so that dynamic stresses could be seen in the kinematic results.
• C-frame stress results from the kinematic model were reviewed and moments in time at which the c-frame
stresses peaked were noted.
• These peak-stress events in the motion were used as time instances from which to pull joint/interface
forces and moments to apply to the c-frame FEA model.
• It was found that force/moment vs. time plots at the interface locations smoothed when a rigid
representation of the c-frame was used in the kinematic simulation and when a more realistic version of
the arm guide was modeled with contact between the roller inside the channel instead of a primitive
translational joint. A model with these modifications was used to pull FEA load case input forces and
moments.
• Structural analysis (FEA) for the baseline model was carried out using worst case loading identified from
kinematic simulation. FEA results for the baseline were reviewed and stress patterns and load paths
were observed to match well with crack locations for in-service units.
• Structural analysis for the modified model was carried out using worst case loading identified from
kinematic simulation. The stresses were compared against the baseline and modified model at all critical
locations.
Fig.2: C-Frame & Cylinder motion curves
Results & Discussions
• High stresses are observed on the bottom, middle and top portion of the C-frame
• Worst case loading, forces are identified and tabulated in respective tables .
• Force and moment vs. time plots were created for all the interfaces to the c-frame. Worst-case stress
time inputs were captured from charts and are shown in the respective pictures.
• The stress results summary of different load cases are tabulated below.
Simulation Driven Innovation 2

3. Load case 1 kinematic analysis results:
Load case 2 kinematic analysis results:
FEA analysis results:
Fig.3: Baseline model Fig.4: Improved model
Benefits
Accurate prediction of dynamic forces helped to arrive the best field fix-geometry by collaborative work
and able to validate using FEA. As a out com, the side plates were also increased in thickness from ¼” to
5/16”.
Challenges
Mathematical representation of the actual operation of Automatic lift by using Motion solve
Simulation Driven Innovation 3

4. Future Plans
Providing production solution by performing detailed analysis
Conclusions
• Based on relative comparison of the above base line and improved design, the stress values for
the modified models have reduced remarkably when compared with the baseline design.
• The stresses are varying within 15-35% between the baseline and new design.
Simulation Driven Innovation 4