scholarly journals Determination of bond model for 7-wire strands in pretensioned concrete beam

2021 ◽  
Vol 61 (6) ◽  
pp. 740-748
Author(s):  
Vadzim Parkhats ◽  
Rafał Krzywoń ◽  
Jacek Hulimka ◽  
Jan Kubica
Keyword(s):  
Finite Element ◽  
Strain Distribution ◽  
Concrete Beam ◽  
Bond Stress ◽  
Image Correlation ◽  
Finite Element Models ◽  
Bond Model ◽  
Comparison Results ◽  
Pretensioned Concrete

A correct choice of a bond model for prestressing tendons is crucial for the right modelling of a structural behaviour of a pretensioned concrete structure. The aim of this paper is the determination of an optimal bond model for 7-wire strands in a prestressed concrete beam produced in a precast concrete plant of Consolis Poland. ATENA 3D is used to develop finite element models of the beam that differ only in a bond stress-slip relationship of tendons. The bond stress-slip relationships for modelling are taken from the results of bond tests carried out by different researchers in previous years. Moreover, for comparison purposes, a simplified 2D model of the beam is created in Autodesk Robot. The strain distribution at the time of the strand release is found for each of the finite element models. The determined strain distributions are compared with the strain distribution in the beam established by an experimental test using a measuring system based on a digital image correlation. On the basis of the comparison results, the most appropriate bond models for 7-wire strands used in the beam are identified.

scholarly journals High-Fidelity Sensitivity Analysis of Modal Properties of Mistuned Bladed Disks Regarding Material Anisotropy

2018 ◽  
Author(s):  
Adam Koscso ◽  
Guido Dhondt ◽  
E. P. Petrov
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Coordinate Systems ◽  
Bladed Disks ◽  
Bladed Disk ◽  
Material Orientation

A new method has been developed for sensitivity calculations of modal characteristics of bladed disks made of anisotropic materials. The method allows the determination of the sensitivity of the natural frequencies and mode shapes of mistuned bladed disks with respect to anisotropy angles that define the crystal orientation of the monocrystalline blades using full-scale finite element models. An enhanced method is proposed to provide high accuracy for the sensitivity analysis of mode shapes. An approach has also been developed for transforming the modal sensitivities to coordinate systems used in industry for description of the blade anisotropy orientations. The capabilities of the developed methods are demonstrated on examples of a single blade and a mistuned realistic bladed disk finite element models. The modal sensitivity of mistuned bladed disks to anisotropic material orientation is thoroughly studied.

scholarly journals Finite element modelling of monotonic pull-out test of deformed steel rebar embedded in well-confined concrete

2021 ◽  
Vol 331 ◽  
pp. 05012
Author(s):  
Patria Kusumaningrum ◽  
Gigih Muslim Prayogo ◽  
Sri Tudjono
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Empirical Equation ◽  
Bond Stress ◽  
Confined Concrete ◽  
Bond Slip ◽  
Steel Rebar ◽  
Bond Model ◽  
Pull Out ◽  
Good Agreement

A finite element study carried out using LS DYNA and aimed to simulate the monotonic pull-out test of deformed steel rebar embedded in concrete is presented in this paper. Three models of the interface between deformed steel rebar and well-confined concrete, i.e. perfect bond model and two bond-slip models are observed and compared. Bond stress-slip response and rebar stress-slip response obtained numerically are validated with experimental data and empirical equations available from the literature. The full bond model overestimates the response, providing higher rebar stress. In the bond-slip models, good agreement is observed between numerical and experimental bond stress and rebar Stress–slip responses. The empirical equation of bond-slip proposed by Murcia-Delso and Shing (2014) is found to overestimate the peak bond stress.

Comparison of femur strain under different loading scenarios: Experimental testing

2020 ◽  
Vol 235 (1) ◽  
pp. 17-27
Author(s):  
Ievgen Levadnyi ◽  
Jan Awrejcewicz ◽  
Yan Zhang ◽  
Yaodong Gu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Strain Distribution ◽  
Element Model ◽  
Surface Strain ◽  
Image Correlation ◽  
Loading Conditions ◽  
Bone Implant ◽  
Bone Stiffness

Bone fracture, formation and adaptation are related to mechanical strains in bone. Assessing bone stiffness and strain distribution under different loading conditions may help predict diseases and improve surgical results by determining the best conditions for long-term functioning of bone-implant systems. In this study, an experimentally wide range of loading conditions (56) was used to cover the directional range spanned by the hip joint force. Loads for different stance configurations were applied to composite femurs and assessed in a material testing machine. The experimental analysis provides a better understanding of the influence of the bone inclination angle in the frontal and sagittal planes on strain distribution and stiffness. The results show that the surface strain magnitude and stiffness vary significantly under different loading conditions. For the axial compression, maximal bending is observed at the mid-shaft, and bone stiffness is also maximal. The increased inclination leads to decreased stiffness and increased magnitude of maximum strain at the distal end of the femur. For comparative analysis of results, a three-dimensional, finite element model of the femur was used. To validate the finite element model, strain gauges and digital image correlation system were employed. During validation of the model, regression analysis indicated robust agreement between the measured and predicted strains, with high correlation coefficient and low root-mean-square error of the estimate. The results of stiffnesses obtained from multi-loading conditions experiments were qualitatively compared with results obtained from a finite element analysis of the validated model of femur with the same multi-loading conditions. When the obtained numerical results are qualitatively compared with experimental ones, similarities can be noted. The developed finite element model of femur may be used as a promising tool to estimate proximal femur strength and identify the best conditions for long-term functioning of the bone-implant system in future study.

scholarly journals The Effect of Swinging Ball Heads with Different Arrangements in Multi-Point Stretch-Forming Process

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 337 ◽  
Author(s):  
Jian Xing ◽  
Yan-yan Cheng ◽  
Zhuo Yi
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Sheet Metal ◽  
Strain Distribution ◽  
Finite Element Models ◽  
Stretch Forming ◽  
Forming Process ◽  
Forming Quality ◽  
Staggered Arrangement ◽  
Simulation Results

To improve the effect of multi-point stretch forming of sheet metal, it is proposed in this paper to replace a fixed ball head with a swinging ball head. According to the multi-point dies with different arrangements, this research establishes finite element models of the following stretch forming, i.e., fixed ball heads with conventional arrangement, swinging ball heads with conventional arrangement, swinging ball heads with declining staggered arrangement, and swinging ball heads with parallel staggered arrangement, and then numerical simulation is performed. The simulation results show that by replacing a fixed ball head with a swinging ball head, the surface indentation of the part formed was effectively suppressed, the stress and tension strain distribution of the part formed was improved, and the forming quality was improved; the thickness of the elastic pad was reduced, the springback was reduced and the forming accuracy was improved; and when the ball head was applied to a multi-point die with staggered arrangement, a better forming result was achieved, where the best forming result was achieved in combining the swinging ball heads with the multi-point die with a parallel staggered arrangement. Forming experiments were carried out, and the experimental results were consistent with the trend of numerical simulation results, which verified the correctness of the numerical simulation.

Modal Velocity-Based Multiaxial Fatigue Damage Evaluation Using Simplified Finite Element Models

2020 ◽  
Vol 87 (11) ◽  
Author(s):  
Kurthan Kersch ◽  
Elmar Woschke
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Multiaxial Fatigue ◽  
Finite Element Models ◽  
Damage Evaluation ◽  
Geometric Factors ◽  
The Relationship ◽  
General Method

Abstract This work proposes a new method for the fatigue damage evaluation of vibrational loads, based on preceding investigations on the relationship between stresses and modal velocities. As a first step, the influence of the geometry on the particular relationship is studied. Therefore, an analytic expression for Euler Bernoulli beams with a non-constant cross section is derived. Afterward, a general method for obtaining geometric factors from finite element (FE) models is proposed. In order to ensure a fast fatigue damage evaluation, strongly simplified FE-models are used for the determination of both factors and measurement locations. The entire method is demonstrated on three mechanical structures and indicates a better compromise between effort and accuracy than existing methods. For all examples, the usage of velocities and geometric factors obtained from simplified FE models enables a sufficient fatigue damage calculation.

Analysis of Creep Effects in a Concrete Beam Using Various Software

2017 ◽  
Vol 738 ◽  
pp. 79-88 ◽  
Author(s):  
Katarina Tvrda ◽  
Jana Drienovska
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Creep Curve ◽  
Concrete Beam ◽  
Linear Analysis ◽  
Creep Function ◽  
Complex Phenomenon ◽  
Ansys Software ◽  
Creep Effect

This article deals with determination of the strain of the beam caused by the creep effect. Instant deflection and simulation of creep function have been examined by SCIA Engineer, ANSYS and Marc software. Creep is a complex phenomenon, which is in every software configured differently. Therefore we would like to compare results of calculations obtained using various finite element method software. With increasing time, the deformation of a beam becomes non-linear analysis. Analysis involved monitoring of deflection in the middle of the beam depending on the time. In SCIA Engineer construction stages were created with the creep factor based on period of load. In the ANSYS software different method was selected and creep curve of concrete had been defined.

Application of CAE Systems in Forming of Drawpieces with Use Rubber-Pad Forming Processes / Zastosowanie Systemów CAE W Projektowaniu Procesów Tłoczenia Z Użyciem Odkształcalnych Narzędzi

2012 ◽  
Vol 57 (4) ◽  
pp. 1179-1187
Author(s):  
D. Woźniak ◽  
M. Głowacki ◽  
M. Hojny ◽  
T. Pieja
Keyword(s):  
Computer Simulation ◽  
Finite Element ◽  
Numerical Analysis ◽  
Computer Simulations ◽  
Strain Distribution ◽  
Aircraft Engine ◽  
Finite Element Models ◽  
Drawing Process ◽  
Deep Drawing Process ◽  
Rubber Pad Forming

This article shows example result of computer simulations supporting production process of bearing housing of aircraft engine. Verification of both deep drawing process project and tools design were carried out using finite element models implemented in eta/Dynaform 5.8.1 system and LS-DYNA solver. Wrinkling and fracture of the material were the main phenomena subjected to the investigation on the way of numerical analysis. A number of computer simulations were carried out in aim to analyze the deformation and strain distribution in the final product, as well as to eliminate the mentioned defects. In addition the comparison of results of both industrial tests and computer simulation was done.

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