DRIVA an Introduction and Case Studies · Multi-plate Clutch Torque capacity calculated from geometry Coefficient of friction can vary with speed and temperature Oil/clutch temperature
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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
➢ 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
➢ 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
▪ 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.
▪ 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
➢ 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
▪ 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