保时捷刹车舒适性模拟的高级方法
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Advanced Approaches in the Simulation of Brake Comfort -PERMAS User‘s Conference -Leinfelden 2014 -
S. Carvajal, Dr. D. Wallner -Dr. Ing. h.c. F. Porsche AG
Dr. O. Jakubský, P. Sedláček-Porsche Engineering Services s.r.o.
Integrated NVH Development Process
Simulation Method for Brake Comfort Evaluation •Complex Eigenvalue Analysis (CEA): Theoretical Background •CEA: Application of the Method
•CEA: Influence of Disc Cyclic-Symmetry
•CEA: Process
•CEA: Representation of an Unstable Complex Eigenshape •CEA: Results Parameter Variation
Sensitivity Analysis of Friction Material Constants
•Modal Analysis
•CEA
Summary
Integrated NVH Development Process
Development Methodology NVH Brakes
Virtual Optimization Boundary Samples Tests Customer Oriented Field Test
NVH Optimization Simulation
Test Bench Vehicle
NVH Short Test Drive
NVH Release Test Drive Mojácar
NVH Validation Axle Operational Deflection Shape Experimental Modal Analysis
CEA Sensitivity Analysis NVH Basic Optimization Parts
CEA Corner Model NVH Validation Vehicle
NVH Test Drive Mojácar
Simulation Method for Brake Comfort Evaluation
Complex Eigenvalue Analysis (CEA): Theoretical Background
Squealing phenomena are produced by dynamic instabilities of a brake system.In certain frequencies, the system is not able to dampen the energy of self-excited vibration. In unfavourable conditions, this results in the emission of sound waves, which manifest themselves as squealing.Motion equation of the system:
Due to the contribution of the damping matrix the eigenvalues have following form:
The stability of the system is characterised for every Eigen frequency by the damping parameter:
DR > 0:unstable system => risk of squeal events!DR < 0:stable system
-Dr. Ing. h.c. F.Porsche AG -Slide 4where:
M mass matrix G gyroscopic matrix D damping matrix N circulatory matrix K stiffness matrix λeigenvalue
eigenvector
where:
d damping parameter f Eigenfrequency DR damping ratio i ∙
² 0
CEA: Application of the Method
2010
2014
Elements 240 000222 288 Nodes 416 000383 990 DOFs 1150 000 1 121 349 Contact DOFs 5 412 6 828 Eigenmodes
142217Complex Eigenmodes 141228 Rotational speeds 8080 Permas Version V12.XX.XXX V14.00.432CPU 8*AMD Opteron
@ 3GHz 8* Intel Xeon @ 2.9 GHz Memory
7.5 GB RAM 4.75GB scratch
40 GB RAM 15.65 GB scratch Total calculation time
90 min
18 min / -80 %