scholarly journals Material Constitutive Models for Engineered Cementitious Composites

2021 ◽  
Vol 2 (01) ◽  
pp. 8-16
Author(s):  
Youkhanna Dinkha ◽  
James Haido
Keyword(s):  
Sliding Mode ◽  
Constitutive Models ◽  
Multiple Cracks ◽  
Fracture Width ◽  
Reinforced Beams ◽  
Structural Applications ◽  
Opening Mode ◽  
Structural Responses ◽  
Element Approach ◽  
Experimental Findings

The necessity for realistic constitutive models that represent ECC's behavior under load grows as research in ECC progresses from material creation to structural applications. Constitutive models of ECC can be used to simulate structural responses when paired with the finite element approach. These simulations are helpful in gaining a better understanding of how ECC's unique features, such as tensile ductility and fracture width controlling, may be translated into enhanced structural performance. In this work, phenomenological models for 1D are presented which includes the constitutive models for plain ECC under tension compression, as well as reinforced beams behavior under bending. The models given lay the groundwork for more growth in this subject, which is desperately needed. as result, monotonic loading applications for specific structures showed their variety, weaknesses were also found. These include the tendency to predict a tougher and stronger structural reaction than experimental findings. This is because the multiple cracks can only deform in the opening mode, but not in the sliding mode.

scholarly journals Numerical Simulation of the Fracture Behaviour of High-Performance Fibre Reinforced Concrete by Using a Cohesive-Crack-Based Inverse Analysis

2021 ◽  
Author(s):  
Alejandro Enfedaque ◽  
Marcos G. Alberti ◽  
Jaime C. Gálvez ◽  
Pedro Cabanas
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Inverse Analysis ◽  
High Performance ◽  
Fracture Behaviour ◽  
Constitutive Models ◽  
Cohesive Crack ◽  
Fibre Reinforced Concrete ◽  
Steel Fibres ◽  
Structural Applications

Fibre reinforced concrete (FRC) has become an alternative for structural applications due its outstanding mechanical properties. The appearance of new types of fibres and the fibre cocktails that can be configured mixing them has created FRC that clearly exceed the minimum mechanical properties required in the standards. Consequently, in order to take full advantage of the contribution of the fibres in construction projects, it is of great interest to have constitutive models that simulate the behaviour of the materials. This study aimed to simulate the fracture behaviour of five types of FRC, three with steel hooked fibres, one with a combination of two types of steel fibres and one with a combination of polyolefin fibres and two types of steel fibres, by means of an inverse analysis based on the cohesive crack approach. The results of the numerical simulations defined the softening functions of each FRC formulation and have pointed out the synergies that are created through use of fibre cocktails. The information obtained might suppose a remarkable advance for designers using high-performance FRC in structural elements.

Damage Inspection and Assessment on a Transmission Angle Tower in Coastal Areas

2013 ◽  
Vol 671-674 ◽  
pp. 650-654
Author(s):  
Peng Yun Li ◽  
Bo Chen ◽  
Yu Zhou Sun
Keyword(s):  
Structural Model ◽  
Wind Loading ◽  
Transmission Tower ◽  
Line System ◽  
Steel Material ◽  
Transmission Angle ◽  
Commercial Package ◽  
Loading Effects ◽  
Structural Responses ◽  
Element Approach

The field inspection and safety assessment of a transmission angle tower are actively carried out in this study. The field measurement and inspection are firstly introduced and then the structural model is constructed based on finite element approach with the aiding of commercial package ANSYS. The equation of motion of the transmission tower-line system is established for numerical analysis. The gravity, base settlement and dynamic wind loading are applied on the tower to examine the structural responses. The deformation and stresses distribution of the transmission angle tower are computed to explore the damage reasons. The made observations indicate that the peak stresses of some members are large than the permitted yielding stresses of steel material. The damage event is induced by coupling loading effects

scholarly journals Behavior of Cross Arms Inserted in Concrete-Filled Circular GFRP Tubular Columns

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2280 ◽  
Author(s):  
Fang Xie ◽  
Ju Chen ◽  
Qian-Qian Yu ◽  
Xinlong Dong
Keyword(s):  
Fiber Reinforced Polymer ◽  
Stress And Strain ◽  
Tubular Columns ◽  
Reinforced Polymer ◽  
Steel Bars ◽  
Structural Responses ◽  
The Cross ◽  
Experimental Findings ◽  
Glass Frp ◽  
Good Agreement

Fiber-reinforced polymer (FRP) materials nowadays have attracted much attention in both retrofitting of aged infrastructure and developing of new structural systems attributed to the outstanding mechanical properties. Extensive studies have been performed on concrete-filled glass FRP (GFRP) tubes for the potential application in piling, poles, highways overhead sign structures and bridge components. The new hybrid member also provides an alternative solution for traditional transmission structures. However, the connection between concrete-filled GFRP tubes and cross arms has not been fully understood. In this paper, an experimental study and theoretical analysis were conducted on the behavior of cross arms inserted in concrete-filled circular GFRP tubular columns. Steel bars with a larger stiffness in comparison with GFRP tubes were selected here for the cross arm to simulate a more severe scenario. The structural responses of the system when the cross arms were subjected to concentrated loads were carefully recorded. Experimental results showed that the concrete-filled GFRP tubes could offer a sufficient restraint to the deformation of the cross arm. No visible cracks were found on the GFRP tube at the corner of the cross arm where the stress and strain concentrated. Theoretical solutions based on available theories and equations were adopted to predict the displacement of the cross arms and a good agreement was achieved between the prediction results and experimental findings.

Crack-Propagation Rate in 7075-T6 Plates Under Cyclic Tensile and Transverse Shear Loadings

1969 ◽  
Vol 91 (4) ◽  
pp. 764-769 ◽  
Author(s):  
Soushiro Iida ◽  
A. S. Kobayashi
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Sliding Mode ◽  
Crack Propagation Rate ◽  
Propagation Rate ◽  
Opening Mode ◽  
Direct Stiffness ◽  
Maximum Opening

Crack-propagation rate in 7075-T6 tension plates was determined for central cracks initially oriented in 45, 60, and 90 deg, to the width direction of the tension plates which were loaded cyclically. Opening and sliding mode of stress-intensity factors, K1 and K2, were determined by the method of direct stiffness for curved cracks generated from these initially slanted cracks. Crack-propagation rates, Δa/ΔN, were then plotted against the maximum opening mode of stress-intensity factor, K1, in the presence of sliding mode of stress-intensity factor, K2. Comparison between the corresponding crack-propagation rate in control specimens without K2 showed that the propagation rate is definitely increased in the presence of K2.

Integrated Workflow with Experimentation, Modeling, and Field Studies Enhances Fracture Diversion Design in Carbonate Reservoirs

2021 ◽  
Author(s):  
Abdul Muqtadir Khan ◽  
Zinaida Usova ◽  
Alexey Yudin
Keyword(s):  
Guar Gum ◽  
Parametric Design ◽  
Cost Effective ◽  
Field Studies ◽  
Acid Dissolution ◽  
Fracture Width ◽  
Carrier Fluid ◽  
Entry Points ◽  
Tight Carbonate ◽  
Experimental Findings

Abstract Multiple near-wellbore diverters and their applications exist in the industry. However, understanding of their effectiveness in carbonate acid fracturing applications still has unanswered questions, mainly due to the lack of knowledge on how the fracture width develops at entry points with continuous acid dissolution. This continuum needs to be understood through integrated modeling and experimentation at the yard-scale, and field-scale perspectives. An advanced numerical model was used to analyze the width development in varying calcite/dolomite fractions and acid concentrations. A robust diversion pill was developed during extensive testing, and its performance was validated in the laboratory using a slot test. The goal was to create a system with reliable bridging ability and low permeability to ensure isolation. Multimodal particles help to ensure effective bridging and plug stability. A similar bridging test was conducted at the yard scale with a small pump and low-pressure line setup leading to an 8-mm inside diameter pipe. Results from the laboratory were validated in the yard test to see parameters affecting the bridging. Finally, a well-specific robust workflow was constructed for diversion pill design. Modeling done on a high-resolution fracture hydrodynamics and in-situ kinetics model showed that width development in different scenarios varied from 1.5 to 3.0 mm. Laboratory testing was performed in 0.31- to 063-inch width rectangular slots to normalize the flow rate/area of the cross section, and the plug experienced pressure up to 1,200 psi for several hours at temperatures from 115 to 205°F. No extrusion was observed during the test, which is a valid indicator of plug stability. Sensitivity to flow conditions and carrier fluid properties were estimated. The diversion slurry was mixed in a 0.5 wt% solution of guar gum and displaced at pump rates 100 to 999 ml/min. A yard test was designed to see the bridging of the pill at various concentrations of 75 to 300 lbm/1,000 gal and rates of 0.5 to 3 gal/min. All the laboratory- and yard-scale experimental findings were combined with field case studies to understand fracture bridging for dynamic diversion applications. A workflow using modeling and advanced volumetrics design was devised to enhance the diversion success in field applications. This led to formulating a parametric design measure β, which showed direct correlation and effectiveness on the diversion process. This study gives a 360° solution-based understanding of diversion physics. The proposed combination of mechanical and chemical diversion is a cost-effective method for multistage fracturing. Current comprehensive research involving digitized cores and advanced modeling has significant potential to make this a reliable method to develop tight carbonate formations around the globe.

Fatigue Mechanism Revealed through Multistage Strength Degradation of Notched Concrete Beams under Sequential Loading

2012 ◽  
Vol 197 ◽  
pp. 36-40
Author(s):  
Zi Hai Shi ◽  
Yukari Nakamura ◽  
Masaaki Nakano
Keyword(s):  
Concrete Beam ◽  
Degradation Mechanism ◽  
Strength Degradation ◽  
Multiple Cracks ◽  
Fe Model ◽  
Structural Members ◽  
Cracking Behavior ◽  
Load Carrying ◽  
Spatially Distributed ◽  
Experimental Findings

Under cyclic loading, the material weakening processes in structural members inevitably involve multiple cracking originating from some of the spatially-distributed initial flaws and imperfections, and hence diverse cracking behaviors can be expected. It is known from previous studies on multiple cracks that, the cracking behavior in a structural member can abruptly change as a crack or a number of cracks reach a critical value of crack propagation, causing sudden strength degradation. In this study, by applying sequential loads at different locations of the same FE model of a notched beam, it is shown that this unique strength degradation mechanism can repeatedly occur as cracks propagate under sequential loads, leading to multistage strength degradation of the member. This result is in line with early experimental findings that the load-carrying capacity of a notched concrete beam under bending decreases in a similar fashion as the sizes of multiple initial notches are arbitrarily increased. This study has important implications for understanding the fundamental fatigue mechanisms of various engineering materials.

scholarly journals Numerical Simulation of the Fracture Behavior of High-Performance Fiber-Reinforced Concrete by Using a Cohesive Crack-Based Inverse Analysis

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 71
Author(s):  
Alejandro Enfedaque ◽  
Marcos G. Alberti ◽  
Jaime C. Gálvez ◽  
Pedro Cabanas
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Inverse Analysis ◽  
High Performance ◽  
Constitutive Models ◽  
Fiber Reinforced Concrete ◽  
Cohesive Crack ◽  
Fiber Reinforced ◽  
Steel Fibres ◽  
Structural Applications

Fiber-reinforced concrete (FRC) has become an alternative for structural applications due its outstanding mechanical properties. The appearance of new types of fibres and the fibre cocktails that can be configured by mixing them has created FRC that clearly exceeds the minimum mechanical properties required in the standards. Consequently, in order to take full advantage of the contribution of the fibres in construction projects, it is of interest to have constitutive models that simulate the behaviour of the materials. This study aimed to simulate the fracture behaviour of five types of FRC, three with steel fibres, one with a combination of two types of steel fibers, and one with a combination of polyolefin fibres and two types of steel fibres, by means of an inverse analysis based on the cohesive crack approach. The results of the numerical simulations defined the softening functions of each FRC formulation and have pointed out the synergies that are created through use of fibre cocktails. The information supplied can be of help to engineers in designing structures with high-performance FRC.

Modeling the Influence of Build Orientation on the Monotonic and Cyclic Response of Additively Manufactured Stainless Steel GP1/17-4PH

2017 ◽  
Author(s):  
Sanna F. Siddiqui ◽  
Nathan O’Nora ◽  
Abiodun A. Fasoro ◽  
Ali P. Gordon
Keyword(s):  
Stainless Steel ◽  
Mechanical Performance ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Constitutive Models ◽  
Material Behavior ◽  
Cycle Fatigue ◽  
Cyclic Response ◽  
Build Orientation ◽  
Experimental Findings

Rapid prototyping has led to strides in improved mechanical part design flexibility and manufacturing time. Along with these advances, however, is the extremely high costs associated with additively manufacturing components that can limit a comprehensive understanding of the mechanical performance of these materials. This can be circumvented through the use of constitutive models which can both support experimental findings in addition to providing approximations of expected material behavior. The present study has demonstrated the influence of build orientation on as-built direct metal laser sintered (DMLS) stainless steel (SS) GP1/17-4PH, manufactured along varying orientations in the xy build plane, through strain-controlled tension and completely reversed low cycle fatigue experiments. Experimental findings from monotonic tension testing are used to model failure surfaces, which can be used to approximate failure regions for DMLS SS GP1 manufactured along varying build orientations within the horizontal xy build plane. Further, a Chaboche model is used to simulate the cyclic response of this material based upon experimental findings through low cycle fatigue testing. Conclusive findings from these models are used to assess the vital role that build orientation plays in affecting the mechanical performance of additively manufactured materials.

Multiscale Modelling of the Influence of Damage on the Thermal Properties of Ceramic Matrix Composites

2010 ◽  
Vol 73 ◽  
pp. 65-71 ◽  
Author(s):  
Jalal El Yagoubi ◽  
Jacques Lamon ◽  
Jean Christophe Batsale
Keyword(s):  
Thermal Loading ◽  
Interfacial Crack ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Cracking ◽  
Fiber Direction ◽  
Multiple Cracks ◽  
Matrix Composites ◽  
Structural Applications ◽  
The Matrix

Ceramic matrix composites (CMC) are very attractive materials for structural applications at high temperatures. Not only must CMC be damage tolerant, but they must also allow thermal management. For this purpose heat transfers must be controlled even in the presence of damage. Damage consists in multiple cracks that form in the matrix and ultimately in the fibers, when the stresses exceed the proportional limit. Therefore the thermal conductivity dependence on applied load is a factor of primary importance for the design of CMC components. This original approach combines a model of matrix cracking with a model of heat transfer through an elementary cracked volume element containing matrix crack and an interfacial crack. It was applied to 1D composites subject to tensile ant thermal loading parallel to fiber direction in a previous paper. The present paper compares predictions to experimental results.

Interface Strength Between Sub-Micron Thin Films in Opening and Sliding Delamination Modes

2002 ◽  
Author(s):  
Tadahiro Shibutani ◽  
Tetsu Tsuruga ◽  
Qiang Yu ◽  
Masaki Shiratori
Keyword(s):  
Thin Films ◽  
Fracture Toughness ◽  
Evaluation Method ◽  
Sliding Mode ◽  
Stress Singularity ◽  
Interface Strength ◽  
Interface Fracture ◽  
Interface Toughness ◽  
Interface Fracture Toughness ◽  
Opening Mode

Delamination between thin films is classified into two types: opening mode and sliding mode. Corresponding to each mode, there is the interface strength between thin films. This paper aims to evaluate interface strength between the sub-micron thin films for opening mode and sliding mode, respectively. We already developed the evaluation method of interface fracture toughness for opening mode on the basis of fracture mechanics concept elsewhere. Moreover, the evaluation method of sliding mode is proposed and the interface strength between thin films for an advanced LSI is evaluated as the fracture toughness by using both methods. In both modes, the stress singularity appears in the vicinity of the edge of interface and governs the delamination. The criterion of crack initiation for each mode is evaluated as the interface toughness. The fracture toughness at the edge of interface in sliding mode is lower than that in opening mode.

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