The objective of this paper is to present and compare the results of numerical solutions of contact problem for two types of seats subjected to typical sitting loadings. The first seat is made of a typical hyperelastic foam, the other is designed with an auxetic polyamid spring skeleton. Computer simulations of the seat structure under a typical static loading exerted by a human body are performed by means of ABAQUS FEA. The model provides an insight into deformation modes and stress field in relation to geometric and material parameters of the seat structure.The other type of seat, due to the fact of global auxecity and progressive springs characteristics reduces contact stress concentrations, giving an advantegous distribution of pressure and provides the sensation of physical comfort. The proper seat skeleton shape leads to an improvement of ergonomic quality.
SUMMARYThis paper presents numerical study of deformation and stresses in seat skeleton elements subject to static and dynamic pressure loads. Elastic skeleton made of polyamide or elastomer is taken as an example of a seat material. Auxetic type of seat structure ensures the reduction of real contact stresses between human body and seat, making it more comfortable than typical. FEM analysis is performed using ABAQUS system. Numerical calculations are carried out to determine the nonlinear stiffness characteristics of seat springs. The study makes possible the selection of material and structural topology fulfilling design constraints and additional recommendations concerning structural flexibility, stability and optimal reduction of contact stresses. This paper presents an application of the theoretical prediction to solve the practical problem.Keywords: auxetic structures, seat, utility load, contact problem STUDIUM PROJEKTOWE NAD AUKSETYCZN¥ STRUKTUR¥ SZKIELETU SIEDZISKA Artyku³ przedstawia studium obliczeniowe elementów szkieletu siedziska wykonanych z elastomeru lub poliamidu poddanych typowym obci¹¿eniom statycznym i dynamicznym od siedzenia. Auksetyczne w³asno ci struktury szkieletu siedziska powoduj¹ redukcjê naprê¿eñ kontaktowych miêdzy cia³em cz³owieka i siedziskiem, czyni¹c je bardziej komfortowym w u¿ytkowaniu. Obliczenia przeprowadzono programem ABAQUS metod¹ elementów skoñczonych. W wyniku otrzymano nieliniowe charakterystyki sprê¿yn siedziska. Studium obliczeniowe pozwala na wybór materia³u i kszta³tu sprê¿yn spe³niaj¹cych warunki projektowe dotycz¹ce wytrzyma³o ci, podatno ci stabilno ci oraz optymalnej redukcji naprê¿eñ kontaktowych. Praca prezentuje zastosowanie teoretycznych rezultatów do rozwi¹zañ stosowanych w praktyce.S³owa kluczowe: struktury auksetyczne, siedzisko, obci¹¿enie u¿ytkowe, zagadnienie kontaktu
The objective of this paper is to investigate the effects of scale of an auxetic cellular material sample on the evaluation of elastic properties. Size and boundary effects are studied in detail. This is achieved by conducting computer simulations of the auxetic structure under the typical loading exerted by the compression and simple shearing test performed by means of ABAQUS FEA. The material microstructure is discretized by the plane network of Timoshenko beam elements. The results of the studies give insight to the scale effects. Structures with designed properties can be potentially used for engineering applications.
This paper presents micromechanical approach to assessment of elastic properties of composite polyurethane-carbon foams. Analysis is based on speci c choice of RVE combined with micro-macro transition. It leads to evaluation of strength and elastic constants of a composite. Foam behaviour is investigated numerically. Solid skeleton part shape is based on the tetrahedron cut out with spheres. 3D unit cell model is FE discetized. Calculations are performed for foams of selected densities using ABAQUS system. The comparison shows good agreement between the theoretical approach and experimental data. The presented method may be applied to design novel materials such as graphitized foam and nano composites and tailoring these materials for desired elastic properties.
This paper presents numerical simulation of a sandwich plate bending. Two types of plates are considered: with a cellular honeycomb core and with the cellular auxetic core. Finite element method (FEM) calculations are performed by means of ABAQUS system for determination of plates bending stiffness. Three methods are presented. The first one, numerically expensive, is based on detailed modelling of cellular core structure, the second applies laminated plate theory with an equivalent core stiffness, the third applies theory of composite beams. The results show limitations of applicability of abovementioned models to stiffness modelling. The influence of core lattice geometry parameters on plate stiffness is studied.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.