using simdesigner on convertible top latch mechanism · using simdesigner on convertible top latch...

Using SimDesigner on Convertible Top Latch Mechanism

Stephen Doncov – ASC Incorporated –CAE Specialist

John Ellison – MSC.Software –Application Engineer

-add your logo here-About ASC: History

ASC was founded in 1965 by the late Heinz Prechter, a talented and creative automotive entrepreneur

ASC developed and installed the first OE sunroof for 1967 Ford Cougar

ASC re-introduced convertibles to the North American market, with the 1982 Buick Riviera

ASC re-introduced modern retractable hardtop with the 1995 Mitsubishi Spyder

ASC has produced more than 800,000 convertibles in 40 different vehicle programs

In May 2002, ASC Incorporated was acquired by Questor ManagementCompany, LLC

Today, ASC is a leading automotive supplier of convertible systems and specialty vehicles, with 3 design and engineering centers and 11manufacturing facilities

’67 Ford

Cougar

’82 Buick

Rivera

’95 Mitsubishi

Spyder

Chevy

SSR

Dearborn Deuce Convertible

-add your logo here-Objective:

To Perform a Virtual DVP on a Header Latch System

• Identify Areas/Specifications of Non-Conformance• Provide Feedback to Design Engineering for Changes• Get Closer to a Design-Analyze-Confirm mode and away

from Design-Build-Test• Save Time & Money

-add your logo here-Approach:

Utilize CATIA V5 FEA/DMU Kinematics and SimDesigner Motion/NonLineartools for all CAE even though design is based in CATIA V4.

Why?• Through evaluation, V5 analysis tools are robust, fast and easy to use. • Time lost in converting V4 models to V5 made up with productivity of V5.• CAE group preparing for migration to V5 and SimDesigner Products. We

will be leading ASC forward!• SimDesigner NonLinear expands ASC’s CAE capability and maintains goal

of utilizing integrated products.• Common V5 Database allows ASC to utilize completed V5 analysis models

performed by MSC.Software.

-add your logo here-Background:

What is a header latch?

• The Header Latch secures the Front Bow of a Convertible Top to the Windshield Header or Frame Structure.

Typical Characteristics• Stroke (Distance Latch Hook can be away from

header and grab the receiver)• Min/Max Operational Efforts.• Capture Range (Fore/Aft and Lateral Miss-

alignment)• Max Load Capacity• Abuse

Locked

Unlocking

Unlocked

-add your logo here-

Benchmarking:SimDesigner Nonlinear validated against physical testing on previous model latch design prior to initiating current project

Physical Test Set Up Physical Results


Benchmarking:SimDesigner Nonlinear results

• Areas of high stress and failure found during SimDesigner Nonlinear analysis closely matched those found during physical testing.

• Redesign yielded no failure which also correlated with physical testing.

Virtual Test Results


Benchmarking: Abuse and Ultimate Load AnalysesUse SimDesigner Nonlinear for requirements where the

ultimate strength value could be exceeded:• Benchmark of prior model design provided confidence in

results.• Benchmark provides insight into establishing failure

points.• Analytically test design (Virtual DVP&R) prior to physical

testing and construction of tools for manufacturing.• Verify criteria for acceptable design.

-add your logo here-Requirements:

Physical Latch DVP&R requirements transferred to Virtual Requirements where applicable.

• Operation Efforts to Close and Open.40-60 N

• Latch Handle Abuse.600 N opening force applied to end of handle294 N Side Load

• Max Load.4900 N load applied to Hook.

-add your logo here-Analysis: Motion Study

• Operation Efforts to Close and Open.40-60 N




Modelling approach• Utilize CATIA’s DMU

Kinematics tool to move model to fully opened position.

• Build Motion constraints.Handle to ground.

• Insert torsional springs.Hook clamp body to roll pin 1Lock button to long roll pin

Analysis: Operation Effort of Header Latch


Modelling approach• Approximate leaf springs

using linear springs/dampers.

Handle detent springHandle to idler spring



Modelling approach• Simulate stroke of latch

Prismatic joint allows receiver to travel along stroke direction of latch

• Approximate load of topcover.

Utilized linear spring along travel path.As receiver is pulled load will increase from zero to a maximum value



Modelling approach• Utilized 3D contact (could

not use 2D contacts)• All contacts planar

Hook to Roll PinHandle stop to detent springLock button to mounting bktLock button to handleIdler to handle (2 places)Handle to lock buttonHook to reciever (not shown)



ResultsForce required to close latch mechanism exceeds range from specification.


40-60N Range


Simulation Replay



What did we learn?• Motion study confirmed operation of latching system.

Interaction of Latch Handle and Idler Bracket.Verified latch capture range (latch stroke).Verified operation of handle lock.

• Handle efforts exceeded requirement.Finer hook adjustment needed to reduce handle efforts.Leaf springs too stiff (Handle Detent, Handle to Idler).

• Discovered issue with 2D Contacts.

Analysis: Motion Study Results


2D contacts vs. 3D contacts.• Latch assembly contains many contacts which are planar.• Latch contacts ideally should be modelled as 2D contacts.

KISS approach.• 2D contacts compute much faster than 3D contacts.

Essential for complex Mechanisms.• We could not use 2D contacts because we kept getting a

“curves are not co-planar” • Generated CR 47465 to address the issue.• We use 2D contacts often and this issue needs resolution.

Analysis: 2D Contact Issue

-add your logo here-Analysis: Nonlinear Study

• Operation Efforts to Close and Open.

40-60 N



-add your logo here-Latch Handle Vertical Abuse

Modelling approach for 600N vertical load analysis• Use SimDesigner Linear analysis to determine which parts

could be omitted from the SimDesigner Nonlinear analysisParts that did not reach yield strength and were not critical tomaintain the integrated of the mechanism (i.e. connecting pins) were eliminated• Omitted the clamp_body, detent)spring, handle_spring, hook, receiver,

rubber_stop, and both roll_pin_1 and roll_pin_2


Modelling approach for 600N vertical load analysis• Meshing

All parts were original meshed with tet4’s.Ran a SimDesigner Nonlinear analysis to identify where the hot spots for high stress might be.The hot spots were found to be in the handle part• All parts except handle remained tet4’s but local mesh and local sag

conditions were implement around the areas of contact• Handle was set to tet10 meshing and local mesh and local sag conditions

were implement around the areas of contact and the hot spots

Encountered issue with combining Tet4/Tet10 in R13 • Correction to MSC.Marc solver has been implemented and will be

available soon


Modelling approach for 600N vertical load analysis• Boundary Conditions

Constraints • Clamp mounting bracket and both handle_to_idler_hinge pins.

Contact • Set to Inactive for bodies that would not collide and to eliminate

consideration of bodies contact themselves.• Set to Glue for bodies that did not need to rotate or translate relative one

another.• Set to Touch for bodies that could come in and out of contact with one

another or would need to rotate or translated relative to one another.Loading• Apply 600 N load in vertical direction to face near handle end


Modelling approach for 600N vertical load analysis• Material Properties

ZA8 – Zinc used for all components except the connector pins were model as 1010 – SteelNonlinear material curves were provided by customer although theexactness of the curves was not validated with physical testing• It’s critical that the exact treatment of each material is consider as any

amount of cold-working or heat treatment can lower or raise the yield and ultimate strength and dramatically effect the nonlinear material curve

Solver Settings• Contact bias at 90% and Coulomb friction activated


Results from original design

• Ultimate stress was exceed in handle at approximately60% of load


Results from modified design.

• Handle satisfies vertical abuse specification.



40-60 N



-add your logo here-Latch Handle Side Load Abuse

Modelling approach for 294N side load analysis• Same boundary conditions, material properties, meshing,

solver settings as 600N vertical load analysis• Omitted the lock_button and long_roll_pin, in addition to,

the parts omitted for the 600N vertical load analysis

-add your logo here-Latch Handle Side Load Abuse

Results• Original design satisfied side load abuse design specification.



40-60 N




<<4900N>> load in latch stroke directionModelling approach for 4900N load analysis• Use SimDesigner Linear analysis to determine which parts

could be omitted from the SimDesigner Nonlinear analysisParts that did not reach yield strength and were not critical tomaintain the integrated of the mechanism (i.e. connecting pins) were eliminated• Omitted all parts except the clamp_body, hook, roll_pin_1 and receiver


<<4900N>> load in latch stroke directionModelling approach for 4900N load analysis• Meshing

All parts were original meshed with tet4’s.Ran a SimDesigner Nonlinear analysis to identify where the hot spots for high stress might be.• Tet4 meshing on receiver and roll pin• Tet10 meshing used on clamp_body and hook• Local mesh and local sag conditions were implement around the areas of

contact and the hot spots


<<4900N>> load in latch stroke directionModelling approach for 4900N load analysis• Boundary Conditions

Constraints • Applied advanced restraint to roll_pin_1 allowing only translational

displacement in latch stroke direction • No consideration was made of rotational DOFs

Encountered issue with applying advance restraints in non-global axes system • Workaround was to change orientation of assembly to align latch stroke

direction with a principal axis.• Feature to be included in future release.



Contacts• Used inactive, glue, and touch as described in 600N latch abuse analysis

Encountered issue with overlapping volume of clamp body and hook• Initial interference was interpreted as an undesired pressure force • Workaround was to modify hook volume to eliminate interference• Product Development is working to include this functionality in the future



Loading• Applied distributed force of 4900 across roll pin in latch stroke direction

Encountered issue with modelling roll_pin_1 as rigid body • Initial intention was to apply an enforced displacement to a rigid

roll_pin_1 as the flexibility of roll_pin_1 was determined negligible • This option was negated as it is not currently possible to post process

reaction loads on rigid bodies solely within SimDesigner Nonlinear making it impossible to know at what displacement the 4900N requirement was achieved

• Product Development is working to include this functionality in the future


Modelling approach for 4900N load analysis• Material Properties

ZA8 – Zinc : Clamp Body1010 – Steel : Roll Pin 4130 – Steel : Receiver12L14 – Steel : Hook

• Solver SettingsContact bias at 90% and Coulomb friction activated

<<4900N>> load in latch stroke direction


<<4900N>> load in latch stroke direction

Results• Original design achieved max load design specification.

-add your logo here-Conclusions

Significance of Work• By utilizing Design-Analyze-Confirm for approach, failure

points in the handle were identified and addressed; essentially replacing the first stage of physical prototyping and testing.

• A substantial amount of time and money was saved by determining early on the weak areas in the initial design which would not meet spec.

• Testing is done to confirm results. Failures trying to meet specifications can be troubling to customers. Performing a test to confirm predicted success scores big confidence points with customers!

-add your logo here-Conclusions

Benefits of SimDesigner for CATIA V5• One common interface and database that can be shared

by designers and analysts.• Seamless transition between CATIA design and analysis

and MSC.Software technology.• Issues identified in software. When you have to use your

own tools and things don’t work, issues become real. Important to getting resolution to issues.

using simdesigner on convertible top latch mechanism · using simdesigner on convertible top latch...

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