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  • Author: A. Zbiciak x
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Constitutive Modelling and Numerical Implementation of SMA Material with Internal Loops

Abstract

The article presents a constitutive model for Shape Memory Alloys (SMA) along with result of dynamic simulations of SMA model. The applications of devices incorporating SMA in civil engineering focus mostly on mitigation of the seismic hazard effects in new-build and historical buildings or improvement of fatigue resilience. The unique properties of SMA, such as shape memory effect and superelasticity give promising results for such applications. The presented model includes additional phenomenon of SMA – internal loops. The paper shows the method of formulation of physical relations of SMA based on special rheological structure, which includes modified Kepes’s model. This rheological element, introduced as dual-phase plasticity body, is given in the context of martensite phase transformation. One of the advantages of such an approach is a possibility of formulation of constitutive relationships as a set of explicit differential equations. The application of the model is demonstrated on example of dynamic simulations of three dimensional finite element subjected to dynamic excitation.

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Dynamics of an Orthotropic Railway Bridge in the Light of European Standards

Abstract

The paper presents selected aspects of dynamic numerical simulations of an orthotropic steel railway bridge loaded by high-speed trains. The model of moving loads was adopted in accordance with the models set out in the applicable standards. The current European code requirements are referred in which the computer calculations of the dynamic response of the structure are the basis for assessing the suitability of the structure to carry high-speed rail traffic (v > 160 km/h). In this research the calculations are based on the author’s method of generating traffic loads in Abaqus FEM environment. It is emphasized in the paper that in most commercial FEM codes (including Abaqus), moving loads are not implemented in modules responsible for defining of loads. The author’s approach to this issue allowed to obtain results confirming its adequacy. In the longer term, the authors will develop a plan to adapt this algorithm in order to generate traffic loads on bridges discretized as spatial and plane numerical models.

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Numerical Analysis of Diaphragm Wall Model Executed in Poznań Clay Formation Applying Selected Fem Codes

Abstract

The paper presents results of numerical calculations of a diaphragm wall model executed in Poznań clay formation. Two selected FEM codes were applied, Plaxis and Abaqus. Geological description of Poznań clay formation in Poland as well as geotechnical conditions on construction site in Warsaw city area were presented. The constitutive models of clay implemented both in Plaxis and Abaqus were discussed. The parameters of the Poznań clay constitutive models were assumed based on authors’ experimental tests. The results of numerical analysis were compared taking into account the measured values of horizontal displacements.

Open access
Use of the Finite Element Method in Predicting Vibrations of Sandwich Beams and Plates Resting on Deformable Foundations Subjected to Moving Loads

Abstract

This paper presents the capabilities of ABAQUS finite-element program [1] in modelling sandwich beams and plates resting on deformable foundations. Specific systems of sandwich beams and plates separated by an elastic core layer were subjected to the action of point and distributed moving loads. A few theoretical examples are provided to present different techniques of modelling the foundations and the moving loads. The effects of the boundary conditions and of the foundation parameters on the deflections of the analysed structures are also presented.

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Validation of the cone penetrometer suitability for determining the state of soil

Abstract

The subject matter of this paper is assessment of the suitability of a dynamic cone penetrometer for determination of the state of soil. The principle of operation of the dynamic cone penetrometer, similar to commonly used DPL penetrometers, is described in the paper. Next the results of investigation conducted in Poland using a new dynamic cone penetrometer are presented. A series of measurements were performed in real field conditions. An attempt was made to correlate the results obtained with the dynamic and static cone penetrometers (CPT) respectively. These correlations were then subjected to validation to obtain a preliminary evaluation of the suitability of the dynamic cone penetrometer for determining the state of soil.

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Static and Dynamic Parameters of Railway Tracks Retrofitted With Under Sleeper Pads

Abstract

The paper presents results of the laboratory tests made for the prototype resilient under sleeper pads in the Warsaw University of Technology laboratory unit. These pads are dedicated to reduce vibrations transmitted to the vicinity of the railroad and to improve the resistance of the railroad structure. The laboratory testing program was carried out for elastomeric materials (polyurethane and rubber based) due to the PN-EN 16730 standard. The obtained values of the key parameters were used in order to determine the insertion loss vibration level by applying analytical method. The paper presents the influence of selected parameters i.e. static and dynamic moduli on the reduction of vibration and structure-borne sound level.

Open access