scholarly journals Experimental and Analytical Study on Residual Stiffness/Strength of CFRP Tendons under Cyclic Loading

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5653
Author(s):  
Chao Wang ◽  
Jiwen Zhang
Keyword(s):  
Residual Strength ◽  
Analytical Study ◽  
Damage Model ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Proposed Model ◽  
Residual Stiffness

Based on tension–tension fatigue tests, this paper investigated the mechanical property degradation of carbon fiber reinforced polymer (CFRP) tendons from a macroscopic perspective. According to the degradation regularity, this paper proposed a normalized phenomenological fatigue model based on the residual stiffness/strength of CFRP tendons during the fatigue loading process. In this paper, the residual stiffness of CFRP tendons were tested at five stress ranges, while the residual strength was tested at four stress ranges. In order to validate the reliability and applicability of proposed fatigue damage model, the predictions of proposed model and cited models from the literature are discussed and compared. Furthermore, experimental results from literatures were adopted to verify the accuracy of the proposed model. The results showed that the proposed model is applicable to predict both residual stiffness and residual strength throughout fatigue life cycle and has a better accuracy than models from the literature. Moreover, the three-stage degradation can be observed from the degradation processes of stiffness and strength at each stress level.

Experimental Study on the Durability of Square-Section Columns Externally Wrapped with Carbon Fiber Reinforced Polymer

2011 ◽  
Vol 291-294 ◽  
pp. 2205-2210
Author(s):  
Ling Ling Zhang ◽  
Jian Xun Ma ◽  
Ling Zhang
Keyword(s):  
Experimental Study ◽  
Carbon Fiber ◽  
Environmental Factors ◽  
Damage Model ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Load Bearing ◽  
Freeze And Thaw ◽  
Reinforced Polymer ◽  
Bonding Length

This paper mainly studied the durability of square-section columns wrapped with CFRP by experiments. Three kinds of columns, such as columns without CFRP, columns wrapped with CFRP entirely and columns wrapped with CFRP strips, were considered. The environmental factors included dry and wet cycles of saltwater, the coupled action of freeze and thaw cycles and dry and wet cycles. The results show that the load bearing capability and the ductility of the columns wrapped with CFRP are improved greatly. The external environments have an ignoring effect on the damage model, the ductility and the stiffness of axial compressed columns, but they have an extremely effect on the load bearing capability. The load bearing capability of the columns wrapped with CFRP strips decreased more than that of the columns wrapped with CFRP entirely. And no matter how environments，the bonding between column and CFRP has no damage in this experimental study with the bonding length of 100mm.

Mechanistic model for fiber crack density prediction in cyclically loaded carbon fiber-reinforced polymer during the damage initiation phase

2018 ◽  
Vol 53 (8) ◽  
pp. 993-1004 ◽  
Author(s):  
Chandrashekhar P Hiremath ◽  
K Senthilnathan ◽  
Niranjan K Naik ◽  
Anirban Guha ◽  
Asim Tewari
Keyword(s):  
Fatigue Strength ◽  
Carbon Fiber ◽  
Polymer Composite ◽  
Crack Density ◽  
Fatigue Loading ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Damage Initiation ◽  
Reinforced Polymer

Prediction of the fiber crack density (as one of the microstructural damages) for unidirectional fiber-reinforced polymer composite under monotonic tensile load, using strength models, has been reported in the literature. However, the microstructural damage prediction for a fiber-reinforced polymer subjected to fatigue loading is still a challenge. In this work, a progressive damage initiation model was developed to predict the fiber crack density in carbon fiber-reinforced polymer composite subjected to fatigue loading. A stochastic model was used for modeling the fiber fatigue strength. Reduction in effective life of the fiber was modeled using linear Miner’s rule. Effect of fatigue strength parameters on fiber crack density was found to be considerable compared to the effect of interface shear strength. At a low number of cycles, fiber crack density obtained from the model was in good agreement with the experimentally measured fiber crack density.

Microstructural damage based micromechanics model to predict stiffness reduction in damaged unidirectional composites

2018 ◽  
Vol 37 (12) ◽  
pp. 797-807 ◽  
Author(s):  
Chandrashekhar P Hiremath ◽  
K Senthilnathan ◽  
Niranjan K Naik ◽  
Anirban Guha ◽  
Asim Tewari
Keyword(s):  
Finite Element Analysis ◽  
Crack Density ◽  
Fatigue Loading ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Damage State ◽  
Element Analysis ◽  
Microstructural Damage ◽  
Reinforced Polymer ◽  
Stiffness Model

Prediction of the residual stiffness of the carbon fiber reinforced polymer composite, subjected to fatigue loading, can be performed using some of the phenomenological models. However, it is still a challenge to find the stiffness based on the known microstructural damage state (that was developed irrespective of the load history). In this work, two micromechanics-based models were developed to predict reduction in the stiffness of the damaged composite. Fiber crack density and interface debonding was used to define the microstructural damage state of the composite. These models account for the fiber crack density in the form of change in either geometry (equivalent ellipsoid model) or material property of the fiber (reduced stiffness model). The microstructural damage state in the unidirectional carbon fiber reinforced polymer composite, obtained from the on-axis tension–tension fatigue loading, was used to validate the models. The results from reduced fiber stiffness model were compared against experiment and finite element analysis for the given microstructural damage. The stiffness obtained using reduced fiber stiffness model was in good agreement with that obtained from the experiment. However, reduced fiber stiffness model underestimated reduction in stiffness compared to finite element analysis.

scholarly journals Linear-Nonlinear Stiffness Responses of Carbon Fiber-Reinforced Polymer Composite Materials and Structures: A Numerical Study

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 344
Author(s):  
S. S. R. Koloor ◽  
A. Karimzadeh ◽  
M. R. Abdullah ◽  
M. Petrů ◽  
N. Yidris ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Composite Structures ◽  
Numerical Study ◽  
Damage Model ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Nonlinear Stiffness ◽  
Reinforced Polymer ◽  
Cfrp Composite

The stiffness response or load-deformation/displacement behavior is the most important mechanical behavior that frequently being utilized for validation of the mathematical-physical models representing the mechanical behavior of solid objects in numerical method, compared to actual experimental data. This numerical study aims to investigate the linear-nonlinear stiffness behavior of carbon fiber-reinforced polymer (CFRP) composites at material and structural levels, and its dependency to the sets of individual/group elastic and damage model parameters. In this regard, a validated constitutive damage model, elastic-damage properties as reference data, and simulation process, that account for elastic, yielding, and damage evolution, are considered in the finite element model development process. The linear-nonlinear stiffness responses of four cases are examined, including a unidirectional CFRP composite laminate (material level) under tensile load, and also three multidirectional composite structures under flexural loads. The result indicated a direct dependency of the stiffness response at the material level to the elastic properties. However, the stiffness behavior of the composite structures depends both on the structural configuration, geometry, lay-ups as well as the mechanical properties of the CFRP composite. The value of maximum reaction force and displacement of the composite structures, as well as the nonlinear response of the structures are highly dependent not only to the mechanical properties, but also to the geometry and the configuration of the structures.

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