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1 © Copyright, Confidential, Tata Motors Ltd

Shailesh Patil

Kiran Karale

Fyaz Farook

Date – 11th June, 2014

Tata Motors Ltd

Cab Door Latch Opening effort reduction using Altair MV & MS


Company Profile

• Tata Motors Limited is India's largest Automobile Company established in 1945.

• Consolidated revenues of INR 2,32,834 crores in 2013-14.

• Leader in commercial vehicles in each segment, and among the top in passenger

vehicles.

• World's fourth largest Truck and Bus manufacturer.

• Tata Motors is committed to improving the quality of life of communities by working

on four thrust areas - employability, education, health and environment.


• Objective

• Cab door latch opening effort reduction.

• Statement Of Problem

• To design a Cab door latch with minimum opening effort.

• Scope

• Cab door latches of TML passenger and commercial vehicle.

• Continuous design quality improvement & cost reduction programs for all

variants.

• Lead time reduction for new vehicle programs with early CAE feedback


LINK1(Push button)

LINK2(Lever)

LINK3(Pivot)

LINK4(Cam)

Latch Load Transfer Path

Final Dislodgement of Door Happens

In Striker Link


Lever

Pivot

Link

Cam

Link

Compression

Spring

Tension

Spring Latch

Base

Surface to Surface

Rigid Contacts

Cab Door Latch Details


(B) Latch Mechanism

• Compression Spring Stiffness, free length

• Tension Spring Stiffness, free length

• Lever - Pivot point to Load application point distance

• Cam link profile

• Pivot link profile

Parameters Affecting Latch Opening Effort

(A) Door Handle

• Push Button Spring stiffness

(C) Door Assembly

• Primary & Secondary seal stiffness


Design1 Design2 Design3

Lever Length Modification Cam Link Modification

Design Proposals


Latch MBD Model

Total bodies : 4

Type of Contact Modeled: Impact

Analysis Type: Transient


Identify Design variable

(spring properties, Link

shapes)

Latch Assembly

Hypermesh (.hm file)

Import .hm file to MV

MBD model with latch

graphics in .h3d format

Define joints, contacts

motion , Markers &

required outputs

Latch Assembly CAD

Data Run Transient

Analysis

Process Methodology

Plot Outputs in

Hypergraph

Measure Latch

opening effort

Effort <

Target

Yes

Prototype

No


Latch MBD Model Simulation


Effort Required For Latch Opening

Max. Value

Effort


• Design Variables Tension spring stiffness

Tension spring free length

Compression spring stiffness

Compression spring free length

• Design Responses Force on lever

• DOE Class Full Factorial

DOE Using Hyperstudy


DOE Results

Response


DOE Results

Initial Design Final Design

Tension

Spring

Stiffness

Compression

Spring

Stiffness

Response

3x

7x

2x

6x

7x

5x

Desirable latch

opening effort band


Summary

• CAE pre-processing, solution & post processing time reduction.

• MBD DOE/Optimization helped to finalize design variables.

Limitations/Challenges

• Contact with flexbody not possible.

• Tuning of contact parameters

Future Goals

• Door assembly and Door seal stiffness effect to be captured

• Multi model DOE/Optimization

• Capturing flex body effect

Benefits


Thank you

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