Upload
nguyenanh
View
225
Download
0
Embed Size (px)
Citation preview
1
Simulate to Innovate
Structural Optimization of Drive Unit Bracket Using OptiStruct
Abstract
This paper deals with optimization of Drive Unit Bracket Assembly for Tow Truck. Drive Unit Bracket Assembly is the important part of the Tow Truck Chassis .The motor which provides the traction to the Equipment is mounted on the Subject Drive Unit Bracket. This paper describes development of a Finite element model and subsequent analysis and simulation of Drive Unit Bracket Assembly consisting of structural members which are designed using basic principles of structural design. Topology & Size optimization is applied to Drive Unit Bracket Assembly considering volume as the objective along with stress constraints. Manufacturing constraints are considered to provide the manufacturability and interpretable design proposal. From the interpretations of Topology & Size optimization, one conservative design is proposed. Drive Unit Bracket Structure is optimized to minimize the mass and the stress requirements.
Introduction
Tow trucks are a vital part of the material handling chain in many operations like large factories, plants,
warehouses, airports and ports where goods have to be transported over significant distances. Tow
trucks offer exceptionally high productivity and economics compared to options like transporting goods
on various types of forklift trucks.
This advantage is even more pronounced when the load to be transported consists of a relatively large
number of small items. Tow trucks are a very efficient and cost competitive form of transporting goods
because they do not carry any goods themselves but pull the load placed in trolleys. A trolley train can
transport a large number of items at a time, something other mobile material handling equipment cannot
do.
Always conscious of the impact on the environment and the rapidly growing need for clean, quiet and
energy efficient material handling equipment, Godrej brings to you electric battery powered towing
solutions with 3 models of tow trucks in capacities of 2,5 and 6 tonne with variants for stand-on and sit-
down operation.
Electric powered tow trucks to cut your transportation costs and time. Godrej Electric Tow Trucks are
ideally suited for indoor work on industrial flooring due to their compact profile and high degree of
manoeuvrability.
The 5 and 6 tonne sit-down models are also available with higher ground clearance and pneumatic
tyres for outdoor use on concrete or paved surfaces. The emphasis on safety, operator comfort,
efficiency and serviceability ensures that the user gets a productive, cost effective and durable towing
solution.
Ms. Nazia .S. Ansari Manager
Godrej Material Handling Div Godrej & Boyce Mfg Co Ltd
Mr. Naushad Ansari Manager
Godrej Material Handling Div Godrej & Boyce Mfg Co Ltd
Mr. Vinay Kulkarni Assistant Vice President Godrej Material Handling
Godrej & Boyce Mfg Co Ltd
2
Simulate to Innovate
Application
The Drive Motor which is the Main power source for the Tow Truck is mounted on the Drive Unit Bracket Assembly as shown in Fig 1 below
Objective
The main objective of this simulation is the re-design of Drive Unit Bracket Assembly with optimum mass while maintaining Stress constraints.
Drive Unit
Bracket Assembly
Drive Unit
Mountings on
Frame
Drive Unit
Fig2 Geometric Model Of Drive Unit Bracket Assembly
Fig1 Layout for Drive Unit Bracket Assembly
3
Simulate to Innovate
Fig 3 Finite Element Model
The elements used for FE model are 2d shell elements for sheet metal components like Drive Unit Plate,Gusset,Channels & Back Plate & 1d rigid elements are used for Welded connections. The material defined for all components is Steel with following properties: Young’s modulus, E =210 GPa Poisson’s ratio, ν =0.30 Density, ρ = 7900 kg/m3 Yield strength, σ =260 MPa Gravity has been defined in the model
Gusset(2 No's)
Drive Unit Plate(1 No)
Fig 3 Shows the Finite Element Model for the Bracket. FE Model Description Total No of Elements= 10256 Total No of Nodes = 10645
GFfIG 3
Design Space
4
Simulate to Innovate
Fig 4 Boundary Conditions:
Process Methodology Design & Non-Design space has been defined for the Optimization Setup in OptiStruct Initially Size Optimization is performed on the Bracket to determine the Optimum material thickness of components used in the Bracket. Size Optimization is a concept level design method that determines the optimum material Thickness for a give optimization problem within the identified Design space. In Size optimization, the thickness of each Element is a Design variable. The problem is solved using several problem formulations to have a better understanding of Underlying physics. Parameters defined during Size Optimization Setup are Design Variables - Gauges of all Parts in Design space Design Constraints - Stress < 130 N/mm2 Objective - Minimize Volume Size Optimization is followed by Topology Optimization in OptiStruct. Design space is again defined for Topology Optimization setup in OptiStruct. Topology Optimization method helps to determine the optimal material Distribution for a given optimization Problem. Parameters defined during Topology Optimization Setup are Design Variables - Density of each element in Design space Design Constraints - Stress < 130 N/mm2 Objective - Minimize Volume
Tractive Effort=538
N
Constraints at 4
Mounting points
Impact exerted during
Bumping =8000 N
5
Simulate to Innovate
The Optimization Process Flowchart is as shown below:
Static Analysis
Design Modification based on Static
Analysis Results
Size optimization
Optimized design
Converged
Topology Optimization
Converged
Optimized Design
6
Simulate to Innovate
Concept Design & Optimization Process
Original Design
Design Modification based on
Static Results
Size Optimization gives
Optimum thickness of 10 mm
for all plates
of the Bracket
Topology Optimization gives
Optimum Material
Distribution for all 10mm
plates
Simulate to Innovate
Size Optimization Results
Fig5Density Plots from Size Optimization show that all the plates can be reduced to 10mm
Topology Optimization Results (Fig 6)
Density Plots from Size Optimization show that all the plates can be reduced to 10mm
Final Design Concept based
on results from Optimization
Optimization Parameters
Design Variables design space
Design Constraints
Objective -
Topology optimization was performed to find the material densities for all the
7
Density Plots from Size Optimization show that all the plates can be reduced to 10mm Thickness
on results from Optimization
Optimization Parameters
Design Variables - Gauges of all Parts in
Design Constraints- Stress < 130 N/mm2
- Minimize Volume
Topology optimization was performed to find the material densities for all the
8
Simulate to Innovate
(Fig 7) Result & Discussion
Due to Manufacturing Constraint, Fabricated design of Bracket was recommended as shown in Fig below
Displacement Plots
Stress Plots
Max Displacement= 1.3mm
Max Stress= 156 MPa which will be shared by mounting
Final Design derived based on Outputs from Topology & Size Optimization
9
Simulate to Innovate
Fig 8 Displacement & Stress Plots For The Fabricated Design
Table for Material Savings
Sr no Part description Thickness(mm) Weight(Kgs)
Material Savings(Kgs)
1 Motor Mounting Plate
Vertical Plates Mounting Plates
16 10 20
9.5 6.4 4.5
-
2 Bend Design of Bracket 10 8
12.4
3 Fabricated Design of Bracket 10 9 11.4
Fabricated Design Of Mounting Bracket
Max Stress= 166 Mpa which will be shared by mounting Bolts
20.4
Simulate to Innovate
Conclusion Using Concept Design & Optimization techniques the weight of the Bracket was reis significant savings in weight and these savings amount to Rs 1240/bracketMonthly production of Tow Truck is 5 Nos. The work presented in this paper is in the early phases of ongoing work and it is important to promising results will strongly demand more detailed Analysis as mentionStudy Benefit Summary • Reduce Development Time
Through OptiStruct's design synthesis approach,CAE is development cycle, thereby driving the design process and enabling a reduction in the number of design iterations • Improve Design Performance
OptiStruct helps to develop structurally sound, lightweight products by applyin advanced optimization methods to solve the design problem. • Explore More Design Alternatives
OptiStruct's advanced optimization engine allows users to combine topology, topography, size and shape optimization methods to create more requirements can also be defined as input to the simulation to create designeasier to interpret and to manufacture.
• Higher Productivity Through
OptiStruct's integrated analysis and optimization approach enables computationally efficient concept design synthesis and design optimization studies. A highly organized and intuitive interface greatly simplifies user effort through the optimization process.
Further Scope of Study
The study was extended to Motor Mounting Brackets used on other Equipments. Topology & Size optimizations techniques of optimization were
plates Density Plots of Size Optimization Results are as shown in Fig
Using Concept Design & Optimization techniques the weight of the Bracket was reand these savings amount to Rs 1240/bracket
Monthly production of Tow Truck is 5 Nos. Hence Annual Savings =74400 Rs (5*1240*12)
The work presented in this paper is in the early phases of ongoing work and it is important to trongly demand more detailed Analysis as mentioned in the further scope of
ct's design synthesis approach,CAE is applied upfront in the product development cycle, thereby driving the design process and enabling a reduction in the number
Design Performance OptiStruct helps to develop structurally sound, lightweight products by applyinadvanced optimization methods to solve the design problem.
Explore More Design Alternatives advanced optimization engine allows users to combine topology, topography, size
and shape optimization methods to create more alternative design proposals. Manufacturing requirements can also be defined as input to the simulation to create design proposals that are easier to interpret and to manufacture.
Higher Productivity Through Hyper Works Integration ted analysis and optimization approach enables computationally efficient
concept design synthesis and design optimization studies. A highly organized and intuitive interface greatly simplifies user effort through the optimization process.
Motor Mounting Brackets used on other Equipments.Topology & Size optimizations techniques of optimization were used to arrive at Optimum sizes
Density Plots of Size Optimization Results are as shown in Fig
10
Using Concept Design & Optimization techniques the weight of the Bracket was reduced by 61% which
=74400 Rs (5*1240*12)
The work presented in this paper is in the early phases of ongoing work and it is important to note these ed in the further scope of
applied upfront in the product development cycle, thereby driving the design process and enabling a reduction in the number
OptiStruct helps to develop structurally sound, lightweight products by applying the most
advanced optimization engine allows users to combine topology, topography, size alternative design proposals. Manufacturing
proposals that are
ted analysis and optimization approach enables computationally efficient concept design synthesis and design optimization studies. A highly organized and intuitive user-
Motor Mounting Brackets used on other Equipments. used to arrive at Optimum sizes of
11
Simulate to Innovate
Initial (Base Design ) Final (Optimised Design) Using optimization, thickness of plates used in the bracket were reduced to 8mm & 6mm.Total Weight reduction of 61% achieved from the Final Optimized Design of Bracket Annual savings from this Analysis amounted to 4,68000 INR ACKNOWLEDGEMENTS The authors would like to acknowledge our company M/s. Godrej and Boyce Mfg. Co. Ltd, Material Handling Equipment Division and Altair’s Technical support. REFERENCES 1. OptiStruct –User’s Manual-Altair Engineering 2. Practical Finite Element Analysis- Nitin S.Gokhale, Sanjay S. Deshpande, Sanjeev V.Bedekar, Anand N.Thite. 3.Altair HyperWorks 3.RADIOSSv11 help Manual.