Mainz
Beitrag zur numerischen Simulation des sitzenden Menschen zur Beurteilung der Auswirkung von Ganzkörperschwingungen
Abstract
dc:descriptionToday the probability of suffering from low back pain is up to 80% for an average adult person. There are various causes for low back pain. Besides pathological changes to the spine or psychological problems the harmful effects of whole-body vibration has been shown in many epidemiological studies. Persons that are exposed to vertical vibrations in a seating position during their daily work like helicopter pilots or occupational drivers are even at increased risk. In order to protect people from an impairment caused by vibrations, the causes and courses of damage have to be investigated closely. Experimental investigations with persons alive are limited because of ethical reasons whereas experiments 'in vitro' can only approximately reveal the dynamical behaviour of the human body. Numerical models are not subjected to these limitations. They allow very detailed and close investigation of the mechanical processes. In this work a three-dimensional physically non-linear model of a seated human has been developed. The neck, thorax, and pelvic region is modelled with simple beam elements. The lumbar spine consists of finite volume-elements allowing an anatomically correct representation. Various material models to describe the mechanical behaviour have been investigated. The linear and non-linear material properties are calibrated with load-displacements-curves from experimental data reported in literature. The time dependant material behaviour of the nucleus, the annulus groundsubstance and collagen fibres is approximated with visco-elastic material models. The visco-elastic parameters are also derived by simulating experiments described in literature. For varification of the dynamical behaviour the eigenfrequencies of the model as well as several transmissions are calculated and compared to experimental data from 'in vivo' measurements. The varification is carried out for the various material models employed. It is revealed that the overall dynamical behaviour does not alter significantly with non-linear or visco-elastic material models. For assessing the risk of health due to whole-body vibration an damage model for the collagen fibres is developed. The damage model is based on the strain energy density so that failure due to impact loading as well as fatigue failure can be considered. To determine the threshold level at which damage occurs the German standard VDI 2057 shall be used. Several vertical vibration time histories are generated and assessed according to VDI 2057. Also the resulting strain energy density of the collagen fibres is calculated. It is shown that the injuriousness of the vibration can be determined with VDI 2057 whereas a coherence of the assessment values from the standard with the damage model cannot be shown.
Degree
thesis:*- Grantor dc:publisher
- Mainz
- Year dc:date
- 2004
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Grunendahl, Arno
- Contributors dc:contributor
-
- Meskouris, Konstantin
Subjects
dc:subject × 5Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger
Identifiers
dc:identifier.*- OAI identifier oai:identifier
- oai:publications.rwth-aachen.de:59754