©VIBROENGINEERING. VIBROENGINEERING PROCEDIA. SEPTEMBER 2013. VOLUME 1. ISSN 2345-0533 53 Simulation Model of Polyurethane Foam for Uniaxial Dynamical Compression D Cirkl and T Hruš SIMULATION MODEL OF POLYURETHANE FOAM FOR UNIAXIAL DYNAMICAL COMPRESSION. D CIRKL AND T HRUŠ D Cirkl 1 and T Hruš Dept. of Applied Mechanics, Faculty of Mechanical Engineering Technical University of Liberec, Studentská 2, Liberec 460 01, Czech Republic E-mail: david.cirkl@tul.cz Abstract. Article deals with definition of model of mechanical properties of polyurethane foam with lumped parameters. The problem is considered from the car driver vibroisolation point of view. Model definition comprises restoring force, damping and frictional forces. It is verified for experimental results obtained from measurement of PU foam specimen with open cells. Apart from empirical way of model constants setting the optimization method of genetic algorithms is used for more simple phenomena. 1. Introduction Polyurethane (PU) foam is a very extensively used material in vibroinsulation field and it is used largely in the field of automobile seat cushioning production. For computer simulation of statistical or dynamical behavior of seat with respect to passenger’s comfort it is necessary to describe the properties of PU foam in sufficient degree which this paper deals with. Properties of polyurethane foam were investigated on opened cells PU foam specimen of cubic shape with size (100×100×50)mm, density 55kg/m 3 , made from material TDI. The specimen was inserted into two parallel rigid plates and deformed by means of hydraulic actuator. Kinematic displacement excitation x(t) has a triangle shape with constant amplitude A=19.5mm, constant mean value A0=A=19.5mm and frequency varied in range f=(0.01÷1.28)Hz. It is given by equation (1), where T=1/f is period of excitation and n=0, 1, 2, ..., ∞ means number of periods (see figure 1). ( ) ( ) ( ) 4 4 ; /2 () . 1 / 2; 1 A T A T t nT for t nT nT T xt t n T for t nT T n T  - ∈ +  =  - - +  ∈ + +     (1) 2. Definition of PU foam model t x(t) 0 A A =A 0 T Figure 1. Triangle kinematic excitation of PU foam specimen. Development of material model of polyurethane foam is documented by many publications. One group of authors uses approach of mechanics of continuum [1, 2] while second one, more often, uses method of models with lumped parameters or strictly mathematical design (e.g. [3, 4, 5]). The level of 1 Corresponding author