A Cohesive Model with Frictional Effects on Strength and Stiffness under Transverse Compression

2014 ◽  
Vol 553 ◽  
pp. 649-654
Author(s):  
Irene Guiamatsia ◽  
Giang Dinh Nguyen
Keyword(s):  
Loading Conditions ◽  
Transverse Compression ◽  
Engineering Structures ◽  
Cohesive Model ◽  
Damage Propagation ◽  
Discrete Fracture ◽  
Compressive Loads ◽  
Constitutive Response ◽  
Strength And Stiffness ◽  
Push Out

Failure develops and propagates through a structure via a complex sequence of competing micro-mechanisms occurring simultaneously. While the active mechanism of surface debonding is the source of loss of stiffness and cohesion, friction between cracked surfaces, upon their closure, acts as a passive dissipation mechanism behind the quasi-brittleness and hence can increase the toughness of the material under favorable loading conditions. In order to numerically study damage propagation, the constitutive response must be able to faithfully capture, both qualitatively and quantitatively, one of the signature characteristic of failure: the energy dissipation. In this paper, we present an interface decohesive model for discrete fracture that is able to capture the apparent enhancement of interfacial properties that is observed when transverse compressive loads are applied. The model allows to seamlessly account for the additional frictional dissipation that occurs when the loading regime involves transverse compression, whether during debonding or after full delamination. This constitutive model is then used to successfully predict the response of realistic engineering structures under generalized loading conditions as demonstrated with the numerical simulation of a fiber push-out test.

Seismic Time-History Analysis of Gravity Dam Based on Nonlinear Finite Element Method

2013 ◽  
Vol 351-352 ◽  
pp. 1047-1051
Author(s):  
He Zhu ◽  
Gang Wang ◽  
Zhen Yue Ma ◽  
Yi Kang Su
Keyword(s):  
Time History ◽  
Nonlinear Finite Element ◽  
Gravity Dam ◽  
Elastic Model ◽  
Nonlinear Finite Element Method ◽  
Initial Stiffness ◽  
Cohesive Model ◽  
Damage Initiation ◽  
History Analysis ◽  
Constitutive Response

A cohesive model (CM) was introduced in this paper. The constitutive response of cohesive behavior depends on a traction-separation description characterized by the initial stiffness, damage initiation threshold, and damage evolution properties.Through the aseismic analysis of a gravity dam, the displacement, stress and anti-sliding safety factor were discussed in the paper, the results were also compared between elastic model (EM) and plastic model (PM). The results shown that the displacement amplitude computed by PM and CM was nearly twice larger than that by EM, and the area of stress concentration became not so obvious. The cohesive model could efficiently simulate the discontinuous structure and the responses of seismic computed by PM and CM were more correspond to actual situation.

A Study on Analysis Method Considering Camber for the Carbody Deflection of the Urban Transit Vehicles

2013 ◽  
Vol 871 ◽  
pp. 323-329
Author(s):  
Jong Duk Chung ◽  
Jang Sik Pyun
Keyword(s):  
Permanent Deformation ◽  
Compressive Force ◽  
Maximum Load ◽  
Loading Conditions ◽  
Element Analysis ◽  
Urban Transit ◽  
Service Load ◽  
Multiple Unit ◽  
Technical Specifications ◽  
Strength And Stiffness

The carbody structure of electric multiple unit (here in after EMU) shall be designed withstand the loading conditions without permanent deformation or any form of damage. And the carbody shall have a minimum design life of 25 years or more in Korea. Loading conditions have a longitudinal compressive force and a vertical load. Camber of the carbody is defined as its curved shape viewed in side elevation. Carbody camber shall be a smooth arc from end to end of the carbody and shall be measured from a datum line drawn between the intersections of the arc with the center lines of the carbody bolsters to a line tangent to the arc midway between bolsters. The carbody shall be built with positive camber such that camber shall remain positive with the carbody at maximum load and shall not bind due to deflection caused by variations of service load. To assess the strength and stiffness of the designed carbody, carbodys designer shall be demonstrated by a programme of finite element analysis and testing shall be carried out in accordance with Korean standard technical specifications. The carbody is manufactured by giving the slope of the deflection to be compensated strength and stiffness. The deflection is camber. So this study analyzes that how camber affects safety and durability of carbody according to the load conditions and revenue service on main-line. Methods and analytical model of carbody structure is introduced to demonstrate them.

Pull-Out and Push-Out Tests for Rubber-to Metal Adhesion

1989 ◽  
Vol 62 (4) ◽  
pp. 757-766 ◽  
Author(s):  
A. N. Gent ◽  
S. Y. Kaang
Keyword(s):  
Large Fraction ◽  
Theoretical Treatment ◽  
Total Force ◽  
Compression Tests ◽  
Cross Sectional ◽  
Pull Out ◽  
Good Accord ◽  
Compressive Loads ◽  
And Control ◽  
Push Out

Abstract A study has been carried out of adhesive failure forces for a steel rod embedded in and bonded to a rubber block. Emphasis has been placed on comparing tension (pull-out) and compression (push-out) forces. A fractional contribution to the pull-out force appeared to be significant for rods having a diameter greater than about 0.5 mm in the present experiments. Indeed, it became a large fraction of the total force when the rod diameter was 1 mm or more. On the other hand, it was negligibly small in push-out experiments. They would therefore be preferred on this basis for measuring the strength of adhesion. But experimental difficulties in carrying out compression tests are considerable. Tall blocks become unstable under large compressive loads, and short ones are markedly stiffer than long ones, due to restraints on their lateral expansion, which are difficult to specify and control. Thus, although measurements of push-out force for a wide variety of samples have been shown to be in good accord with a simple theoretical treatment of debonding, ignoring friction, it is recommended that pull-out tests be retained for assessing the strength of adhesive bonds. Caution is necessary to minimize the effect of friction. The theoretical treatment indicates that the product aL of the rod radius a and the embedded length L should be held smaller than the cross-sectional area of the block in which the rod is embedded.

scholarly journals Structural Analysis of Motorcycle Alloy Wheel

2021 ◽  
Vol 309 ◽  
pp. 01158
Author(s):  
Navuri Karteek ◽  
Kasi V Rao Pothamsetty ◽  
K. Ravi Prakash Babu ◽  
D. Mojeshwara Rao
Keyword(s):  
Impact Load ◽  
Maximum Deflection ◽  
Loading Conditions ◽  
Motor Cycle ◽  
Industry Standards ◽  
Alloy Wheel ◽  
Bending Load ◽  
Impact Bending ◽  
Strength And Stiffness ◽  
Ansys Workbench

Alloy wheels in the motor cycle play major role to carry the load over the spoke wheels. The shape and orientation of the spokes are responsible for withstand the loads which are acting on the alloy wheel rim and hub bearing surface. These alloy wheel spokes are subjected to different types of loads i.e., radial loads, impact load, bending load, torsion load and maximum deflection load. So it is necessary to study the response of the wheel under these types of loads before the product going into the market. In the present article 4 models of motor cycle alloy wheel are modeled based on the dimensions in the reference article. The material chosen for the analysis of the alloy wheel is aluminum alloy which is homogenous in nature having isotropic properties. The magnitude of the five different loading conditions and boundary conditions are taken from the Automotive Industry Standards (AIS). The four models of alloy wheels are analyzed under radial, impact, bending, torsion and maximum deflection loads cases by using by using ANSYS workbench. The results show that all four models are having enough fatigue life, strength and stiffness against the different loading conditions.

Variational Estimates for the Elastoplastic Response of Particle-Reinforced Metal-Matrix Composites

1994 ◽  
Vol 47 (1S) ◽  
pp. S77-S94 ◽  
Author(s):  
Guoan Li ◽  
P. Ponte Castan˜eda
Keyword(s):  
Constitutive Model ◽  
Optimization Problems ◽  
Transversely Isotropic ◽  
Uniaxial Tensile ◽  
Matrix Composites ◽  
Loading Conditions ◽  
Model Composite ◽  
Arbitrary Loading ◽  
Structural Applications ◽  
Constitutive Response

Ductile solids reinforced by aligned elastic spheroidal inclusions, with overall transversely isotropic symmetry, are examined analytically in this paper. Estimates for the effective constitutive behavior of this class of composite materials are obtained in terms of simple optimization problems for general loading conditions, as functions of the particle stiffness, concentration and shape. In particular, explicit expressions are obtained for the yield functions of the composites. The results apply to composites with inclusion shapes ranging from continuous fibers (or needles in the limit of vanishingly small concentration), to approximately spherical, to continuous flat layers (or disks). As an example, we investigate a model composite of the type used in many structural applications, namely, 2124 Al–SiC which is made of a ductile matrix phase (Al) reinforced by hard brittle particles (SiC). The predicted stress-strain responses for these composites are compared with available experimental measurements and numerical calculations. Thus, it is shown that the constitutive model developed in this work predicts fairly accurately the uniaxial tensile experiments of Christman et al. (1989). In addition, the constitutive model is in good agreement with the periodic finite-element calculations of Tvergaard (1990) and Hom (1992), also for uniaxial loading conditions. A significant advantage of the analytical model proposed herein is that it can provide the constitutive response of composites under arbitrary loading conditions, without requiring complex numerical computations.

Experimental investigation of Tied Foam Core sandwich compression performance

2017 ◽  
Vol 22 (2) ◽  
pp. 349-369 ◽  
Author(s):  
Mohamed Adli Dimassi ◽  
Christian Brauner ◽  
Oliver Focke ◽  
Axel Siegfried Herrmann
Keyword(s):  
Compressive Strength ◽  
Failure Modes ◽  
Volume Fraction ◽  
Core Material ◽  
Foam Core ◽  
Compression Tests ◽  
Compression Performance ◽  
Compressive Loads ◽  
X Ray Computed ◽  
Strength And Stiffness

Carbon and glass dry fibre bundles were inserted into a ROHACELL® 71HERO polymethacrylimide foam core under a specific inclination angle and pin pattern in order to enhance the compressive strength and stiffness of the core material. Flatwise compression tests were conducted on pin-reinforced sandwich specimens and unreinforced sandwich to investigate the effect of pin volume fraction and pin material on the compressive mechanical properties and energy absorption characteristics. X-ray computed tomography was performed on tested specimens to investigate the failure modes under compressive loads. It was concluded that the compressive strength is mainly controlled by pin failure due to bending and compression loads at pin base. Moreover, increasing the pin volume fraction improved the compressive properties of the sandwich but using glass fibre pins instead of carbon fibre pins led to a higher increase of the absorbed crushing energy. Finally, an existing analytical model to predict the compressive strength and stiffness has been tested and evaluated.

Design guidance for protection of geomembrane liners in landfill applications

2021 ◽  
Author(s):  
Bryce Marcotte ◽  
Ian Fleming
Keyword(s):  
Room Temperature ◽  
Loading Conditions ◽  
Tire Derived Aggregate ◽  
Current Threshold ◽  
Protection Layer ◽  
Geomembrane Liners ◽  
Strength And Stiffness ◽  
Undrained Loading ◽  
Design Guidance

A new method of evaluating strains and predicting required protection layers that are placed over geomembranes is developed based on the combined effects of the clay strength and stiffness and the cushioning effect of a nonwoven protection layer. Plots giving the required geotextile protection for a different maximum strains are presented for expected landfill pressures under 300 kPa for angular, 38 mm gravel placed above a geomembrane liner for both drained and undrained loading conditions of the clay. A similar plot is also given for tire derived aggregate placed above the liner for pressures under 500 kPa for undrained loading conditions. All tests were conducted at room temperature. For all cases, nonwoven geosynthetic protection layers with mass per unit areas (MUA) exceeding at least 1200 g/m2 were required to limit long term strains below current threshold levels, such as a 4% strain target as given by Rowe and Yu (2019). The MUA of the protection layer, for the particular aggregates and geomembranes tested, is dependent on the loading rate, water content relative to optimum, the silt content, and the activity of the clay below.

scholarly journals Push-out Tests for Determining Shear Strength and Stiffness of Perfobond Connector-Experimental Study

2019 ◽  
Vol 12 (4) ◽  
pp. 225-231
Author(s):  
Khawla A. Farhan ◽  
Muhaned A. Shallal
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Lightweight Concrete ◽  
Steel Tube ◽  
Ultimate Shear Strength ◽  
Concrete Blocks ◽  
Strength And Stiffness ◽  
Square Steel Tube ◽  
Concrete Filled Steel Tubes ◽  
Push Out

This study presents an experimental investigation for push-out tests in order to evaluate the performance of continuous perfobond connectors. A total of five specimens composed of light-weight concrete-filled steel tubes (square and circle sections) with two reinforced blocks were tested. The measured parameters are the compressive strength of the concrete blocks and the type of the section. The specimens were tested under a concentric load applied on the steel tube filled with lightweight concrete; the corresponding slip value was measured   using two LVDTs. The experimental results showed that the ultimate shear strength and stiffness of the square steel tube filled with concrete were higher than that of circular samples. The ultimate shear strength and stiffness increased with an increase of concrete compressive strength, while the corresponding slips    showed decreasing in their values with increase of the compressive strength of the concrete.

Failure of Ductile Materials Subject to Varying Strain Rates

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Y. W. Kwon ◽  
K. S. Tan
Keyword(s):  
Strain Rate ◽  
Failure Criterion ◽  
Strain Rates ◽  
Loading Conditions ◽  
Metallic Material ◽  
Ductile Materials ◽  
Stiffness Properties ◽  
Strength And Stiffness ◽  
Strain Rate Loading ◽  
Nonuniform Strain

Strain rate affects the mechanical properties of ductile materials in terms of their stiffness and strength. In particular, yield and failure strengths and strains depend on the strain rate applied to the materials. When a metallic material is subjected to a typical dynamic loading, the material usually undergoes various strain-rate loading conditions. One of the main questions is whether the material is going to fail or not. To the authors’ best knowledge, there has been no failure criterion proposed for a varying strain-rate loading condition. This paper presents a failure criterion under nonuniform strain-rate loading conditions. Experiments were conducted to support the proposed failure criterion using aluminum alloy AA3003-H14. This study also investigated the that failure envelops in terms of strain rates and the normalized failure strengths. Furthermore, the effects of strain rates on strength and stiffness properties were also examined.

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