Peridynamic Theory for Damage Initiation and Growth in Composite Laminate

2011 ◽  
Vol 488-489 ◽  
pp. 355-358 ◽  
Author(s):  
Erkan Oterkus ◽  
Erdogan Madenci

A recently introduced nonlocal peridynamic theory removes the obstacles present in classical continuum mechanics that limit the prediction of crack initiation and growth in materials. Furthermore, damage growth in composites involves complex and progressive failure modes. Current computational tools are incapable of predicting failure in composite materials mainly due to their mathematical structure. However, the peridynamic theory removes these obstacles by taking into account non-local interactions between material points. This study presents an application of the peridynamic theory for predicting damage progression from a central crack in fiber reinforced composite plates subjected to uniaxial tension loading.

2017 ◽  
Vol 27 (7) ◽  
pp. 963-978 ◽  
Author(s):  
Hadi Bakhshan ◽  
Ali Afrouzian ◽  
Hamed Ahmadi ◽  
Mehrnoosh Taghavimehr

The present work aims to obtain failure loads for open-hole unidirectional composite plates under tensile loading. For this purpose, a user-defined material model in the finite element analysis package, ABAQUS, was developed to predict the failure load of the open-hole composite laminates using progressive failure analysis. Hashin and modified Yamanda-Sun’s failure criteria with complete and Camanho’s material degradation model are studied. In order to achieve the most accurate predictions, the influence of failure criteria and property degradation rules are investigated and failure loads and failure modes of the composites are compared with the same experimental test results from literature. A good agreement between experimental results and numerical predictions was observed.


2020 ◽  
Vol 36 (4) ◽  
pp. 451-463
Author(s):  
M. J. Akbari ◽  
S. R. Kazemi

ABSTRACTSpecific conditions at the tip of a crack and discontinuities in a material are the challenges in analyzing the growth of cracks using conventional methods. In recent years, a method has been developed based on the non-local mechanics, called peridynamic theory, which has improved the analysis process of such structures. In this theory, the points of matter whose displacement or displacement derivatives are discontinuous are not distinguished from other material points. In this paper, we employed the bond-based peridynamic theory to investigate the rate of crack propagation and the path of crack growth in a beam with an initial crack due to low velocity impact. Two beams made of polymethyl-methacrylate (PMMA) and steel alloy with different projectile shapes were considered. The effects of changes in the impact velocity and the fracture toughness were studied and the obtained results were validated with other conducted studies. The crack path was predicted successfully and the branching of the crack was captured. The results confirm the ability of the peridynamic theory to model the crack growth in impact problems.


2014 ◽  
Vol 1004-1005 ◽  
pp. 451-454
Author(s):  
Xiao Qiang Wang ◽  
Wei Tao Zhao ◽  
Bo Fang ◽  
Shao Wei Lu ◽  
Ye Wei Zhang

For different technical reasons, cutouts such as holes in thin-walled structures are inevitable and are of significant technical relevance. Unfortunately open holes usually lead to an undesired stress concentration at the hole vicinity and a reduced load carrying ability of the structure. Therefore the mechanical properties of fiber-reinforced composite laminates with open holes are studied in the paper. The influences of the size and shape of the holes are investigated. A progressive failure finite element model is developed with software ABAQUS. Different failure modes of the composite laminates with various holes are simulated under the Hashin failure criterion. The computational results show that the hole/s have a significant effects on composite laminates properties, and the conclusion can be provided as a good reference for the design of the composite laminates with hole/s.


Author(s):  
Fatemeh Alizadeh ◽  
Navid Kharghani ◽  
Carlos Guedes Soares

Glass/Vinylester composite laminates are comprehensively characterised to assess its impact response behaviour under moisture exposure in marine structures. An instrumented drop weight impact machine is utilised to determine the impact responses of dry and immersed specimens in normal, salted and sea water. The specimens, which had three different thicknesses, were subjected to water exposure for a very long period of over 20 months before tested in a low-velocity impact experiment. Water uptake was measured primarily to study the degradation profiles of GRP laminates after being permeated by water. Matrix dissolution and interfacial damage observed on the laminates after prolonged moisture exposure while the absorption behaviour was found typically non-Fickian. The weight of the composite plates firstly increased because of water diffusion up to month 15 and then decreased due to matrix degradation. The specimens with 3, 6 and 9 mm thickness exhibited maximum water absorption corresponding to 2.6%, 0.7% and 0.5% weight gain, respectively. In general, the results indicated that water uptake and impact properties were affected by thickness and less by water type. Impact properties of prolonged immersed specimens reduced remarkably, and intense failure modes detected almost in all cases. The least sensitive to impact damage were wet specimens with 9 mm thickness as they indicated similar maximum load and absorbed energy for different impact energies.


Landslides ◽  
2021 ◽  
Author(s):  
S. Takayama ◽  
S. Miyata ◽  
M. Fujimoto ◽  
Y. Satofuka

AbstractReducing the damage due to landslide dam failures requires the prediction of flood hydrographs. Although progressive failure is one of the main failure modes of landslide dams, no prediction method is available. This study develops a method for predicting progressive failure. The proposed method consists of the progressive failure model and overtopping erosion model. The progressive failure model can reproduce the collapse progression from a dam toe to predict the longitudinal dam shape and reservoir water level when the reservoir water overflows. The overtopping erosion model uses these predicted values as the new initial conditions and reproduces the dam erosion processes due to an overtopping flow in order to predict a flood hydrograph after the reservoir water overflows. The progressive failure model includes physical models representing the intermittent collapse of a dam slope, seepage flow in a dam, and surface flow on a dam slope. The intermittent collapse model characterizes the progressive failure model. It considers a stabilization effect whereby collapse deposits support a steep slope. This effect decreases as the collapse deposits are transported downstream. Such a consideration allows the model to express intermittent, not continuous, occurrences of collapses. Field experiments on the progressive failure of a landslide dam were conducted to validate the proposed method. The progressive failure model successfully reproduced the experimental results of the collapse progression from the dam toe. Using the value predicted by the progressive failure model, the overtopping erosion model successfully reproduced the flood hydrograph after the reservoir water started to overflow.


Author(s):  
Yu Cheng Liu ◽  
Jin Huang Huang

This paper mainly analyzes the wave dispersion relations and associated modal pattens in the inclusion-reinforced composite plates including the effect of inclusion shapes, inclusion contents, inclusion elastic constants, and plate thickness. The shape of inclusion is modeled as spheroid that enables the composite reinforcement geometrical configurations ranging from sphere to short and continuous fiber. Using the Mori-Tanaka mean-field theory, the effective elastic moduli which are able to elucidate the effect of inclusion’s shape, stiffness, and volume fraction on the composite’s anisotropic elastic behavior can be predicted explicitly. Then, the dispersion relations and the modal patterns of Lamb waves determined from the effective elastic moduli can be obtained by using the dynamic stiffness matrix method. Numerical simulations have been given for the various inclusion types and the resulting dispersions in various wave types on the composite plate. The types (symmetric or antisymmetric) of Lamb waves in an isotropic plate can be classified according to the wave motions about the midplane of the plate. For an orthotropic composite plate, it can also be classified as either symmetric or antisymmetric waves by analyzing the dispersion curves and inspecting the calculated modal patterns. It is also found that the inclusion contents, aspect ratios and plate thickness affect propagation velocities, higher-order mode cutoff frequencies, and modal patterns.


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