Page 3 - raport symulacja

Structural Analysis of Fan Section of Air Handling Unit KMW ZR 30 3/22
on Dynamic Load Defined by Seismic Spectrum OLKILUOTO 3

1. Introduction

1.1. Purpose of the Research
The aim of the research was to obtain stress and displacement maps of the structure of
the air handling unit under load caused by the earthquake with spectrum that is
characteristic for the area of OLKILUOTO 3. On this basis, the critical points of the
structure were identified and the strength of the structure was assessed.

The study was conducted at the request of KMW Engineering, by the team of Computer
Method Department in Faculty of Mechanical Engineering, within in the project
BZ 15/2013/WIM.

1.2. Methods and Software
The calculation model of the air handling unit was generally based on the Finite Element
Method.

Calculations were carried out in LS-DYNA software. A finite element model was created
and the results have been developed in the LS-PREPOST software.

Regarding to the standard [1] the seismic effects and the effects of the other actions
included in the seismic design situation may be determined on the basis of the linear-
elastic behaviour of the structure and the method for determining the seismic effects is
the Modal Response Spectrum Analysis.

Thus for the calculation of a response of the structure subjected to input spectrum load,
such as the acceleration, Response Spectrum Computation Method implemented in LS-
DYNA was used (keyword *FREQUENCY_DOMAIN_RESPONSE_SPECTRUM) [3]. The
method is based on results of modal analysis of a structure, e.g. natural frequencies and
modal shapes. The method assumes that a maximum structure response is a
combination of natural frequencies and mode shapes of the structure using free
vibration analysis.

Two methods of combination of modes were used: Square Root of Sum of Squares
(SRSS) and the complete quadratic combination (CQC), (parameter MCOMB : EQ.0 for
SRSS method, EQ.2 for Complete Quadratic Combination method (CQC) [3]. For models
with closely spaced mode shapes, the CQC method is precise whereas faster SRSS
method estimates less accurate results [2]. The case which gave greater stress has been
selected.

University of Technology and Life Sciences
Faculty of Mechanical Engineering
Department of Computer Methods