1. On the application of a simple computational model for slender transversely cracked beams in buckling problemsMatjaž Skrinar, 2007, izvirni znanstveni članek Opis: This paper discusses the implementation of a simplified computational model that is widely used for the computation of transverse displacements in transversely cracked slender beams into the Euler's elastic flexural buckling theory. Two alternatives are studied instead of solving the corresponding differential equations to obtain exact analytical expressions for the buckling load ▫$P_{cr}$▫ due to the complexity of this approach. The first approach implements wisely selected polynomials to describe the behavior of the structure, which allows the derivation of approximate expressions for the critical buckling load. Although the relevance of the results strongly depends on the proper prime selection of the polynomial, it is shown that the later upgrading of the polynomials can lead to even more reliable results. The second approach is a purely numerical approach and presents the geometrical stiffness matrix for a beam finite element with a transverse crack. To support the discussed approaches, numerical examples covering several structures with different boundary conditions are briefly presented. The results obtained with the presented approaches are further compared with the values from enormous 2D finite elements models, where a detailed description of the crack was achieved with the discrete approach. It is evident that the drastic difference in the computational effort is not reflected in the significant differences in the results between the models.
Ključne besede: columns, transverse cracks, stability problems, buckling load, computational model, polynomial solutions, finite element method, geometrical stiffness matrix
Objavljeno v DKUM: 01.06.2012; Ogledov: 2165; Prenosov: 95
 Povezava na celotno besedilo |
2. Evaluating the bending rigidity of flat textiles with the use of an Instron tensile testerMirosława Kocik, Witold Żurek, Izabella Krucinska, Jelka Geršak, Jan Jakubczyk, 2005, izvirni znanstveni članek Opis: The purpose of this work is to verify the possibility of using an Instron tensile tester for evaluating those mechanical properties of flat textile fabrics which are responsible for their handle properties. A method of evaluating the bending rigidity of woven fabrics was developed. The method consists in axially compressing samples fixed at both ends and placed in a vertical position, which leads to their buckling. The bending rigidity was determined on the basis of the critical maximum force occurring at buckling, and the curvature of the buckled sample which appears as result of the action of this force. The results obtained by this method were compared with those obtained with the use of the FAST system. The good compatibility of both these methods was proved by the correlation coefficients.
Ključne besede: flat textiles, mechanical properties, measurements, fabric handle, bending rigidity, bending moment, curvature, buckling, buckling length
Objavljeno v DKUM: 01.06.2012; Ogledov: 1852; Prenosov: 54
Povezava na celotno besedilo |
3. On critical buckling load estimation for slender transversely cracked beam-columns by the application of a simple computational modelMatjaž Skrinar, 2008, izvirni znanstveni članek Opis: This paper brings new insights into the implementation of a simplified computational model in the prediction of buckling load Pcr for slender beam-type structures with a transverse crack. From among several approaches discussed, two of them produced applicable results exhibiting considerably good agreement with those values from more precise and complex computational models. In the first approach, the critical load value is obtained from numerical solutions of analytically expressed characteristic equations (obtained from governing differential equations). Although producing excellent results, this approach limits the application since an analytical solution of the governing differential equation can only be obtained for moderate structures. The second approach implements a new cracked beam-columnfinite element, derived at on the basis of a fairly accurate approximation of the governing differential equation's solution. It allows for flexible utilization and also yields the smallest compact computational model, thus exhibiting itself as very suitable for inverse identification problems. Numerical examples covering several structures with different boundary conditions are briefly presented in order to support the discussed approaches. The results obtained using the presented approaches are further compared with those values from either references or more complex models, thus clearly proving the quality of the presented compact FE model.
Ključne besede: beam columns, transverse cracks, stability problems, buckling load, computational model, finite element method
Objavljeno v DKUM: 31.05.2012; Ogledov: 2617; Prenosov: 104
Povezava na celotno besedilo |
