driva an introduction and case studies · multi-plate clutch torque capacity calculated from...

SMT, CHARTWELL HOUSE, 67 - 69 HOUNDS GATE, NOTTINGHAM, NG1 6BB

tel. +44 (0)115 941 9839 | fax. +44 (0)115 958 1583

© 2018 SMART MANUFACTURING TECHNOLOGY LTD.

DRIVA an Introduction and Case Studies

Dr Paul Langlois – Software Engineering Director

www.smartmt.com

MASTA

Design, analysis and optimisation of gears, bearings, shaft, casing, systems. Analyses include:

• Static strength

• Fatigue life/durability under static loading conditions

• Frequency domain dynamics – Response to harmonic excitations, gear whine, electric motor, unbalanced masses

• Efficiency

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DRIVA Modules

The DRIVA Modules are a set of modules within MASTA for flexible multi-body dynamics based analysis specialised for geared mechanical systems

Enables the time domain dynamics simulation of complete drivetrains for applications such as

▪ Gear rattle analysis

▪ Engine timing gear trains

▪ Shock loading

▪ Dynamics of wind-turbines under variable wind loading

▪ Drivetrain shifting dynamics vs. control strategy


Details of DRIVA Modelling


Shafts

➢ Shafts along with mounted gears are rigid or flexible bodies

➢ Rigid body motion included

➢ Bodies can be made flexible▪ All 6 degrees of freedom beam

model▪ Imported FE model (does not

currently include gear contacts)

➢ Settings can be applied globally or on a per component basis


Gear meshes

➢ Mesh stiffness can be a simple stiffness derived from ISO 6336 or use MASTA’s Basic LTCA model, including micro geometry (MASTA 9)

➢ Backlash can be included with contact on none, one or two flanks

➢ Tilt stiffness can be included using multiple nodes or a single node with tilt stiffness

➢ Friction model at the mesh based on ISO/TR 14179

➢ Dynamic rating to ISO 6336, ANSI/AGMA 2101-D04 and DIN 3990


Bearings

➢ Full 6 degree of freedom stiffness always used

➢ 3 stiffness models:▪ Fixed concept stiffness for initial

simulations▪ Linearised stiffness using a

System Deflection load case▪ Full non-linear stiffness

➢ Drag due to losses in the bearings from ISO/TR 14179

➢ Dynamic rating to ISO 76, ISO 281 and ISO/TS 16281


Component Rating in DRIVA

There are two ways in which DRIVA can be used to rate the components taking into account the dynamics

➢ Inertia Adjusted Load Cases – A DRIVA analysis is run. Following the analysis MASTA can automatically create new static load cases with “Inertia Adjusted Loads”. The model is then run in System Deflection to rate to these inertia adjusted loads

➢ Damage can be calculated at each time step within the time domain DRIVA analysis and then Miner’s rule (linear damage accumulation assumption) used to calculate total damage for an analysis


Other Components e.g.

➢ Multi-plate Clutch▪ Torque capacity calculated from geometry▪ Coefficient of friction can vary with speed and temperature▪ Oil/clutch temperature calculated during analysis▪ Clutch spring included▪ Pressure can be specified vs time or as an input from DRIVA-

Simulink interface

➢ Torque Convertor - ratio and capacity characteristics

➢ Vehicle Properties▪ Define engine torque map vs speed and throttle▪ Define vehicle mass, frontal area, etc… to automatically

calculate drag


Damping

➢ Accurate damping is important for dynamics

➢ Damping within DRIVA is currently user specified

➢ Rayleigh damping is used, which has stiffness and mass proportional terms

➢ Can be specified globally, per component type and per component


DRIVA-Simulink Interface

➢ Simulink – Multi-purpose dynamic simulation tool well suited to the development of control systems

➢ The DRIVA-Simulink Interface – Develop control system in Simulink and connect to the DRIVA plant model to simulate the mechanical system

➢ Single model for controller development and gearbox analysis

➢ Detailed drivetrain component results (such as component rating) including the interaction between gearbox and controller


Some Case Studies


Case Studies

➢ The following are a selection of case studies from projects using DRIVA

➢ For confidentiality reasons many details are omitted or modified

➢ The aim is to give an idea of the types of problems DRIVA has been applied to

➢ DRIVA is not a fully exploited technology and we are very interested to hear feedback from customers regarding current or future potential applications


Rattle Study in PTO and Tuning torsional spring damper


➢ Problem

▪ US Tier 1 supplier had difficulties in tuning spring dampers to avoid rattle in power take offs

➢ Solution

▪ DRIVA was used to run a multi body dynamics simulation of the system to predict rattle.

▪ Torsional stiffness of a spring damper was tuned in the MASTA model to investigate at which point rattle issues were resolved.

➢ Outcome

▪ Extent of rattle in test and simulation correlated well for a range of spring stiffnesses.

▪ DRIVA helped to design parts which on the first day of testing were shown to eliminate a rattle problem the company had struggled with for 20 years

Hybrid Transmissions system with Dual Mass Flywheel Analysis

Slide 15

➢ Problem

▪ Customer required multi body dynamics analysis to review two dual mass fly wheel designs.

➢ Solution

▪ DRIVA allowed for analysis of the hybrid system using a simplified torsional model that shortened run time.

▪ A non-linear spring stiffness was applied to a standard MASTA component to represent a multiple spring set up.

▪ Torque ripple data was imported in to MASTA via excel at three speeds. This was used to show the smoothing action of the DMF component.

➢ Outcome

▪ DRIVA results included; the torque and speed output from dual mass flywheel, angular accelerations of system shafts and most importantly DMF wind-up. This allowed for predictions in transition point of the system.

Spring Stiffness

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Dynamic Analysis of Engine Timing Geartrain & Belt for Scooter and Medium Size Car


➢ Problem

▪ Customer required rating of designed bearing designations and gears under highly dynamic loading conditions.

➢ Solution

▪ SMT’s DRIVA functionality was used to run a multi body dynamics simulation of the original system in order to calculate the dynamic loads.

▪ Bearings and gears were rated to these loads.

▪ Further system configurations, including both gear and belt configurations, were investigated in a similar manner in order to identify advantages of each.

➢ Outcome

▪ New bearing designations were suggested for original design.

▪ Anti backlash gears were tuned to reduce gear rattle.

▪ Suggested changes taken forward into development

AT Controller Design


➢ Problem▪ Project to develop an AT TCU for a truck application

➢ Solution▪ Project was used as a validation case for DRIVA

▪ In parallel to a Simulink mechanical model SMT’s DRIVA Simulink interface was also used with the existing MASTA model of the system to include as the mechanical model within the plant model for controller development.

▪ Different levels of analysis model were built by MASTA and used to refine shift strategy and shift quality

➢ Outcome▪ The controller performed according to targets within in

vehicle testing

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➢ Problem

▪ OEM with dynamically sensitive engine timing gear train. Scissor gears used to eliminate rattle. Tuning of scissor gear spring difficult, too flexible and gear rattle is seen, too stiff and gear whine develops

➢ Solution – In progress

▪ Implemented coupling of MASTA’s Basic LTCA tooth contact model with DRIVA

▪ MASTA’s DRIVA modules used to run a multi body dynamics simulation of the system to predict rattle and whine

▪ Stiffness of scissor gear spring varied in MASTA model to tune system to avoid rattle and whine

➢ Outcome

▪ Initial results show agreement with current understanding of actual system for rattle

▪ Analysis process ongoing

Gear Rattle/Whine - Engine Timing Gear Train

R&D and Future Developments


R&D and Future Developments

➢ R&D on assumptions made in frequency domain models and improvements for varying torque

➢ Planetary NVH –▪ Improved flexible annulus model▪ Planetary sidebands and R&D on proposed and possible

frequency domain models for planetary NVH

➢ Electric Motors▪ Torque ripple, rotor unbalance and TE dynamic interactions▪ Cosimulation of DRIVA and Electric Motor modelling tools –

Interactions between rotor misalignments, eccentricity in air gap and resulting dynamics

➢ Export to ADAMS via scripting/REXS

➢ Sound Power calculation in DRIVA

➢ Export to acoustics tools such as Actran


Thank you for your attention

CHARTWELL HOUSE, 67-69 HOUNDS GATE

NOTTINGHAM, UK

NG1 6BB

tel. +44 (0) 115 941 9839 | fax. +44 (0) 115 958 1583

www.smartmt.com

© 2018 SMART MANUFACTURING TECHNOLOGY LTD.

driva an introduction and case studies · multi-plate clutch torque capacity calculated from...

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