PSI - Issue 58

Kay Büttner et al. / Procedia Structural Integrity 58 (2024) 95–101 Kay Büttner et al. / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction The modern car is that mass product with the highest complexity at all. Today, the development process at vehicle manufacturers is based on the V-model procedural approach. A visualization of the V-model with a classification of the solution approaches is shown in Fig.1. In the early requirements phase (upper left), all target values for the total vehicle are defined. The elastomeric bushings in various vehicle components have a high influence on several total vehicle properties (dynamics, comfort, durability, acoustics a.o.). Simple kinematic models are initially used to calculate the subsystem and component target values in order to design vehicle dynamics. Later, more detailed MBS models are used, for example, to derive vibration comfort properties. Fatigue strength and durability are also investigated at this stage. For this purpose, well-parameterizable bushing models are used for load data acquisition, which also allow a fast comparison of more than 10000 variants. However, these models have significant weaknesses in representing higher loads. One approach to solving this problem is described in chapter 2 “Target property computing”. Once the target values have been derived to the component level - in this case, the target values of the elastomer component - the design process begins. In this step, the correct solution spaces for the component design must be found quickly. It should be noted that the derivation of component target values can lead to total vehicle development target conflicts in terms of driving dynamics, comfort and durability. The process of automated solution finding, i.e., design value computing (see chapter 3), is basically a multi-criteria optimization problem. Data driven approaches are used in this particular case. The experimental validation of the component properties and the durability verification are located in the lower right part of the V-model. In order to increase efficiency here as well, the relationships between load-dependent property changes and damage patterns must be researched. In chapter 4 “Fast evaluation methods”, a possible solution is presented and its transfer to the development process is described.

Nomenclature A

area of cross section

damping parameters of the several model paths

b n c ax

axial stiffness

stiffness parameters of the several model paths

c n

predicted/calculated stiffness

c pred c true DP

true stiffness

design parameters objective function

f

mount force of the generalised mount main direction

F/F 1

force in axial direction finite element method

F ax

FEM f n (q n )

gain functions of the several model paths

shear modulus

G

γ shear angle MBS multi body systems m h

mass parameter hydro element

number of stiffnesses

N c

number of design parameters

n f

TV

target values shear stress

τ

s Miner q/q n

durability target value

generalised excitation x, y, z set of design parameters / indices for the description of translational spatial directions