scholarly journals Investigation of Confinement Effects for Determining Moment Curvature and Interaction Diagram of Reinforced Concrete Column

2020 ◽  
Vol 2 (1) ◽  
pp. 81-88
Author(s):  
Bikram Bhusal ◽  
Satish Paudel ◽  
Tek Bahadur Katuwal
Keyword(s):  
Cross Section ◽  
Material Model ◽  
Material Behavior ◽  
Confined Concrete ◽  
Confinement Effects ◽  
Reinforced Concrete Column ◽  
Material Models ◽  
Interaction Diagram ◽  
Displacement Capacity ◽  
Bending Capacity

This paper presents the relevance of using various material models to represent the inherent material non-linearity of the cross-section in generating moment curvature relationship. Further, confinement effects are imposed on geometry and P-M diagram is constructed of typical cross-section of column adopted in Nepal. Also, the modelling capability and user defined modelling aspects in terms of section, material behavior is assessed and suitability of modelling criteria to depict the actual displacement capacity is studied. It was observed the ultimate curvature of the un-confined concrete section considered was obtained approximately to be 0.16 per m while for studied confined material models the curvature was obtained approximately to be 0.66 per m. This increase in curvature is due to the confinement effect of the lateral ties. It was observed that the loss of strength of concrete in cover is compensated by use of the confinement since gain in axial and bending capacity of the confined concrete in comparison to unconfined one in compression control region. Hence, it is suggested to adopt the confined material model as user-defined for generating hinge property for non-linear analysis of the structures.

A Study of the Dynamic Behavior of Elastomeric Materials Using Finite Elements

1996 ◽  
Vol 118 (4) ◽  
pp. 503-508 ◽  
Author(s):  
G. E. Vallee ◽  
Arun Shukla
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
Split Hopkinson Pressure Bar ◽  
Material Model ◽  
Element Model ◽  
Material Behavior ◽  
Hopkinson Pressure Bar ◽  
Material Models ◽  
Finite Element Program ◽  
Elastomeric Materials

A numerical method is described for determining a dynamic finite element material model for elastomeric materials loaded primarily in compression. The method employs data obtained using the Split Hopkinson Pressure Bar (SHPB) technique to define a molecular constitutive model for elastomers. The molecular theory is then used to predict dynamic material behavior in several additional deformation modes used by the ABAQUS/Explicit (Hibbitt, Karlsson, and Sorenson, 1993a) commercial finite element program to define hyperelastic material behavior. The resulting dynamic material models are used to create a finite element model of the SHPB system, yielding insights into both the accuracy of the material models and the SHPB technique itself when used to determine the dynamic behavior of elastomeric materials. Impact loading of larger elastomeric specimens whose size prohibits examination by the SHPB technique are examined and compared to the results of dynamic load-deflection experiments to further verify the dynamic material models.

scholarly journals Behavior of an Internally Confined Hollow Reinforced Concrete Column with a Polygonal Cross-Section

2021 ◽  
Vol 11 (9) ◽  
pp. 4302
Author(s):  
Sungwon Kim ◽  
Hyemin Hong ◽  
Taek Hee Han
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Circular Cross Section ◽  
Material Model ◽  
Maximum Load ◽  
Lateral Force ◽  
Analysis Model ◽  
Reinforced Concrete Column ◽  
The Difference ◽  
Saving Effect

The new supporting structure, internally confined hollow reinforced concrete (ICH RC), was suggested by former researchers. It maintains the material saving effect, which is the advantage of the hollow concrete structure, and it solves the brittle fracture problem of the inner wall by the inner steel pipe to make it into the 3-axis confinement state. However, until now, its design and analysis model has been limited to a circular cross-section. In this study, to expand the applicability, research and development of an ICH RC structure with a polygonal cross-section were performed. The material model was developed by defining the constraint stress in the members of the concrete and deriving a reasonable stress-strain relationship. For the column model, it was developed to predict the behavior of the polygonal ICH RC columns by analyzing the axial force-moment correlation, moment-curvature, and lateral force-displacement relationship. Each model was verified not only by comparing with the results of previous experiments but also by analyzing the results according to parameters. The maximum load and ultimate displacement values through the developed model showed the difference with the experimental results within 6% of mean error. It was verified that the proposed analytical model reasonably reflects the behavior of actual columns.

On-Engine Expansion Measurement of Exhaust Manifold for Calibrating Thermo-Mechanical Fatigue FEA Model

2021 ◽  
Author(s):  
Girish J. Kulkarni ◽  
Pravin Kakde ◽  
Vinod Parekar ◽  
Kapil Mestry ◽  
Sandeep Bhosle
Keyword(s):  
Material Model ◽  
Correlation Study ◽  
Material Behavior ◽  
Exhaust Manifold ◽  
Temperature Dependent ◽  
Engine Operation ◽  
Material Models ◽  
Mechanical Fatigue ◽  
Non Linear ◽  
Linear Material

Abstract An attempt was made as part of this work to acquire on-engine measurements to identify how closely current Finite Element Analysis (FEA) models replicate actual on-engine exhaust manifold behavior. Further correlation study with FEA models was performed to understand and eliminate the gaps to improve the overall FEA process. Dry cast iron exhaust manifolds experience thermo-mechanical fatigue (TMF) during engine operation. This is one of the critical failure modes. Literature is available to perform TMF assessment of exhaust manifold e.g. [1–6]. However, it is difficult to accurately predict TMF life of exhaust manifold in FEA due to dependency on multiple factors such as non-linear material behavior [3], temperature dependent material behavior, oxidation effect, creep effect, accuracy in prediction of metal temperatures and joint friction effects. Typically, non-linear material models, creep effects and oxidation effects are accounted by advanced fatigue processing software. Non-linear material models account for material and for temperature dependent non-linearity [4]. These non-linear material model and fatigue parameters are often developed using uniaxial specimen level testing. These doesn’t account for all the complexity during on-engine test due to factors such as friction and bolt loads that can influence manifold behavior. FEA processes for exhaust manifolds are seldom calibrated with on-engine measurements due to the complexity of obtaining these measurements in an environment that has severe temperatures and vibrations. The correlation study highlighted that exhaust manifold was over constrained by excessive clamping in FEA. This raised question on the gasket coefficient of friction (COF) and working preloads. These settings were investigated to get better correlation. Using reduced COF and non-linear material model for manifold capscrews, helped to achieve better correlation. Replacing material properties of manifold capscrews with nonlinear data provided capability to simulate localized yielding of capscrews and hence the corresponding load loss. Using these new settings for few other case studies also showed improvement in correlation of manifold warpage and thermal fatigue life prediction. Outcome of this work was a refined FEA approach which showed better FEA to Test correlation for exhaust manifold subject to thermal loading.

The Effect of Steel Ring Width Variations as the External Confinement on Load-Moment Interaction Behavior of Reinforced Concrete Column

2016 ◽  
Vol 845 ◽  
pp. 188-192
Author(s):  
Endah Safitri ◽  
Iswandi Imran ◽  
Nuroji ◽  
Sholihin Asa'ad
Keyword(s):  
Carrying Capacity ◽  
Analytical Study ◽  
Ring Width ◽  
Structural Member ◽  
Confined Concrete ◽  
Test Results ◽  
Reinforced Concrete Column ◽  
Interaction Diagram ◽  
Moment Interaction ◽  
External Reinforcement

Nowaday, we require higher capacity and ductility of structural member particulary in reinforced concret column in construction world. One way to improve the ductility and carrying capacity of concrete is confining the concrete. To investigate the effects of external confinement on column capacity, an analytical study is carried out. A steel ring external confinement is used in this study. The stress-strain diagrams design for confined concrete are developed by considering different proposed confined models based on width variations of the steel ring. The test results showed that steel ring are effective as external confinement in confining the concrete. Capability of concrete to support load simultaneously is increasing along the width of the ring. Its effect on column capacity is studied in terms of load – moment interaction diagram of column. The presence of external reinforcement expands the interaction diagram of the column particularly when it is in the compression-controlled region.

Concrete Material Models in LS-DYNA for Impact Analysis of Reinforced Concrete Structures

2014 ◽  
Vol 566 ◽  
pp. 173-178
Author(s):  
M.A.K.M. Madurapperuma ◽  
Kazukuni Niwa
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
Impact Analysis ◽  
Material Model ◽  
Material Behavior ◽  
Single Element ◽  
Element Analysis ◽  
Material Models ◽  
Concrete Material ◽  
Rc Structures

Performance of three widely used concrete material models available in LS-DYNA is compared using experimental results of drop-weight impact on a reinforced concrete (RC) beam and high speed aircraft engine missile impact on an RC wall. An overview of these material models and typical concrete material behavior shown by these models using single element analysis are also presented. The study is useful for users who have limited experience on the selection of an appropriate material model for concrete in impact simulation of RC structures.

scholarly journals A Study of Speed of the Boundary Element Method as applied to the Realtime Computational Simulation of Biological Organs

2014 ◽  
Vol 12 (2) ◽  
Author(s):  
Kirana Kumara P
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Computational Simulation ◽  
Material Model ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Processing Unit ◽  
Material Models ◽  
Highly Nonlinear ◽  
Element Method

In this work, possibility of simulating biological organs in realtime using the Boundary Element Method (BEM) is investigated. Biological organs are assumed to follow linear elastostatic material behavior, and constant boundary element is the element type used.  First, a Graphics Processing Unit (GPU) is used to speed up the BEM computations to achieve the realtime performance. Next, instead of the GPU, a computer cluster is used.  Results indicate that BEM is fast enough to provide for realtime graphics if biological organs are assumed to follow linear elastostatic material behavior. Although the present work does not conduct any simulation using nonlinear material models, results from using the linear elastostatic material model imply that it would be difficult to obtain realtime performance if highly nonlinear material models that properly characterize biological organs are used. Although the use of BEM for the simulation of biological organs is not new, the results presented in the present study are not found elsewhere in the literature.

scholarly journals Confinement effects for rubberised concrete in tubular steel cross-sections under combined loading

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
A. Mujdeci ◽  
D. V. Bompa ◽  
A. Y. Elghazouli
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Cross Sections ◽  
Image Correlation ◽  
Combined Loading ◽  
Test Results ◽  
Compression Tests ◽  
Confinement Effects ◽  
Rubber Content ◽  
Dependent Modification

AbstractThis paper describes an experimental investigation into confinement effects provided by circular tubular sections to rubberised concrete materials under combined loading. The tests include specimens with 0%, 30% and 60% rubber replacement of mineral aggregates by volume. After describing the experimental arrangements and specimen details, the results of bending and eccentric compression tests are presented, together with complementary axial compression tests on stub-column samples. Tests on hollow steel specimens are also included for comparison purposes. Particular focus is given to assessing the confinement effects in the infill concrete as well as their influence on the axial–bending cross-section strength interaction. The results show that whilst the capacity is reduced with the increase in the rubber replacement ratio, an enhanced confinement action is obtained for high rubber content concrete compared with conventional materials. Test measurements by means of digital image correlation techniques show that the confinement in axial compression and the neutral axis position under combined loading depend on the rubber content. Analytical procedures for determining the capacity of rubberised concrete infilled cross-sections are also considered based on the test results as well as those from a collated database and then compared with available recommendations. Rubber content-dependent modification factors are proposed to provide more realistic representations of the axial and flexural cross-section capacities. The test results and observations are used, in conjunction with a number of analytical assessments, to highlight the main parameters influencing the behaviour and to propose simplified expressions for determining the cross-section strength under combined compression and bending.

scholarly journals Variation of Passive Biomechanical Properties of the Small Intestine along Its Length: Microstructure-Based Characterization

2021 ◽  
Vol 8 (3) ◽  
pp. 32
Author(s):  
Dimitrios P. Sokolis
Keyword(s):  
Small Intestine ◽  
Orientation Angle ◽  
Axial Direction ◽  
Material Model ◽  
Biomechanical Properties ◽  
Intestinal Wall ◽  
Model Parameters ◽  
Material Models ◽  
Hyper Elastic ◽  
Rat Tissue

Multiaxial testing of the small intestinal wall is critical for understanding its biomechanical properties and defining material models, but limited data and material models are available. The aim of the present study was to develop a microstructure-based material model for the small intestine and test whether there was a significant variation in the passive biomechanical properties along the length of the organ. Rat tissue was cut into eight segments that underwent inflation/extension testing, and their nonlinearly hyper-elastic and anisotropic response was characterized by a fiber-reinforced model. Extensive parametric analysis showed a non-significant contribution to the model of the isotropic matrix and circumferential-fiber family, leading also to severe over-parameterization. Such issues were not apparent with the reduced neo-Hookean and (axial and diagonal)-fiber family model, that provided equally accurate fitting results. Absence from the model of either the axial or diagonal-fiber families led to ill representations of the force- and pressure-diameter data, respectively. The primary direction of anisotropy, designated by the estimated orientation angle of diagonal-fiber families, was about 35° to the axial direction, corroborating prior microscopic observations of submucosal collagen-fiber orientation. The estimated model parameters varied across and within the duodenum, jejunum, and ileum, corroborating histologically assessed segmental differences in layer thicknesses.

A Viscoelastic Correspondence Principle for Plane Membranes Subjected to Lateral Pressure

1983 ◽  
Vol 50 (4a) ◽  
pp. 740-742 ◽  
Author(s):  
B. Stora˚kers
Keyword(s):  
Time Dependence ◽  
Viscoelastic Material ◽  
Lateral Pressure ◽  
Correspondence Principle ◽  
Material Model ◽  
Material Behavior ◽  
Linear Elastic Material ◽  
First Order ◽  
Linear Elastic ◽  
Consistent Approximation

The classical Fo¨ppl equations, governing the deflection of plane membranes, constitute the first-order consistent approximation in the case of linear elastic material behavior. It is shown that despite the static and kinematic nonlinearities present, for arbitrary load histories a correspondence principle for viscoelastic material behavior exists if all relevant relaxation moduli are of uniform time dependence. Application of the principle is illustrated by means of a popular material model.

Non-Linear Stress Analysis of Complex Umbilical Cross-Sections

2002 ◽  
Author(s):  
Svein Sævik ◽  
Knut I. Ekeberg
Keyword(s):  
Cross Section ◽  
Axial Force ◽  
Plastic Material ◽  
Axial Strain ◽  
Development Program ◽  
Full Scale ◽  
Small Scale ◽  
Applied Theory ◽  
Element Formulation ◽  
Material Models

Nexans Norway is, together with Marintek, currently developing a software for detailed analysis of complex umbilical cross-section designs. The software development project combines numerical methods with small-scale testing of involved materials, as well as full-scale testing of a wide variety of umbilical designs, essential for calibration and verification purposes. Each umbilical design is modelled and comparisons are made with respect to global behaviour in terms of: • Axial strain versus axial force; • Axial strain versus torsion; • Torsion versus torsion moment for various axial force levels; • Moment versus curvature for different tension levels. The applied theory is based on curved beam and curved axisymmetric thin shell theories. The problem is formulated in terms of finite elements applying the Principle of Virtual Displacements. Each body of the cross-section interacts with the other bodies by contact elements which are formulated by a penalty formulation. The contact elements operate in the local surface coordinate system and include eccentricity, surface stiffness and friction effects. The software is designed to include the following functionality: • Arbitrary geometry modelling including helical elements wound into arbitrary order; • The helical elements may include both tubes and filled bodies; • Elastic, hyper-elastic, and elastic-plastic material models; • Initial strain; • Contact elements, including friction; • Tension, torsion, internal pressure, external pressure, bending and external contact loading (caterpillars, tensioners, etc.). The paper focuses on the motivation behind the development program including a description of the different activities. The theory is described in terms of kinematics, material models and finite element formulation. A test example is further presented comparing predicted behaviour with respect to full-scale test results.

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