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Статті в журналах з теми "Multidirectional damage"
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Qi, Wenxuan, Weixing Yao, and Haojie Shen. "A multidirectional damage model for fiber-reinforced plastic laminates under static load." Journal of Composite Materials 54, no. 2 (July 2, 2019): 153–66. http://dx.doi.org/10.1177/0021998319854148.
Повний текст джерелаАнотація:
A multidirectional damage model based on continuum damage mechanics for fiber-reinforced composite laminates is proposed in this paper. The influence of three main damage mechanisms, including transverse matrix cracking, local delamination, and fiber breakage, on the multidirectional stiffness properties of composite laminates is analyzed by introducing macro phenomenological damage variables. Then the mechanical behavior of elementary ply in laminates is modeled based on these damage variables. Besides, relations between micro-level damage variables and macro-level damage variables are established. Damage evolution laws of the three damage mechanisms are proposed to predict the degradation of multidirectional stiffness and failure strength of composite laminates under quasi-static loading. The experiment of cross-ply glass fiber-reinforced plastic laminates is carried out, and the prediction results show good agreement with the experimental results.
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Liu, Dunwen, Jianjun Zhang, Yu Tang, Yinghua Jian, and Caiwu Cai. "Damage Analysis of Concrete Structure under Multidirectional Shaped Charge Blasting Using Model Experiment and Ultrasonic Testing." Advances in Civil Engineering 2021 (March 22, 2021): 1–11. http://dx.doi.org/10.1155/2021/6677041.
Повний текст джерелаАнотація:
Quantitatively analyzing multidirectional shaped charge blasting energy distribution and improving the rock-fracturing efficiency have been a challenging problem in blasting and civil engineering. In this work, we carry out four groups of concrete model experiments using ultrasonic testing, comparing conventional blasting, and multidirectional shaped charge blasting. Then, the probability and statistics method is used to quantitatively analyze the blasting damage and the energy distribution. The test results show that ultrasonic testing and statistics model can quantitatively evaluate the damage law and energy distribution of blasting. By comparing with conventional blasting method, the multidirectional shaped charge blasting with V-shaped multidirectional shaped energy groove has achieved the effect of energy accumulation. It increases the distribution of energy in the rock crack district, increases the blasting damage range, and improves the rock-fracturing efficiency of blasting. The V-shaped multidirectional shaped energy groove can be used as a new approach for rock fracturing in similar projects.
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Comola, F., T. Lykke Andersen, L. Martinelli, H. F. Burcharth, and P. Ruol. "Damage pattern and damage progression on breakwater roundheads under multidirectional waves." Coastal Engineering 83 (January 2014): 24–35. http://dx.doi.org/10.1016/j.coastaleng.2013.09.004.
Повний текст джерела
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Li, Wei, Yinghonglin Liu, Peng Jiang, Fuping Guo, and Jiahao Cheng. "Study on Delamination Damage of CFRP Laminates Based on Acoustic Emission and Micro Visualization." Materials 15, no. 4 (February 16, 2022): 1483. http://dx.doi.org/10.3390/ma15041483.
Повний текст джерелаАнотація:
This study investigated the mechanism of delamination damage in the double cantilever beam (DCB) standard test by the use of the strain energy release rate. The curve of the strain energy release rate was verified by the Rise Angle (RA) method. For this purpose, 24-layer carbon fiber/epoxy multidirectional laminates with interface orientations of 0°, 30°, 45°, and 60° were fabricated according to the standard ASTM D5528(13). In the course of this test, acoustic emission (AE) was used for real-time monitoring, and combined with micro visualization, the damage mechanism of composite multidirectional laminates was studied at multiple scales. Combining the AE detection results with micro visualization, it is found that the AE parameters and the damage to multidirectional laminates could realize a one-to-one correspondence. Through the study of the variation of the RA value, load, and strain energy release rate with the crack length, it is proved that the AE parameters can effectively characterize the initiation of delamination damage.
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Birur, A., A. Gupta, and J. Raghavan. "Creep Rupture of Multidirectional Polymer Composite Laminates — Influence of Time-Dependent Damage." Journal of Engineering Materials and Technology 128, no. 4 (June 23, 2006): 611–17. http://dx.doi.org/10.1115/1.2345454.
Повний текст джерелаАнотація:
Evolution of various damage modes with time, in multidirectional laminates of a polymer composite (Hexcel F263-7/T300) subjected to a constant load, was experimentally studied and correlated to experimental creep rupture results to understand the influence of the former on the latter. Influence of various parameters, such as stress, temperature, thickness of inner plies, and outer-ply constraint, on damage evolution was evaluated. Observed damages include transverse (also referred in the literature as matrix cracks) cracking due to in-plane stresses, vertical cracking due to out-of-plane normal stress, delamination due to interlaminar stresses, splitting, and fiber fracture. The sequence of evolution of these damages varied with laminate stacking sequence, stress, and temperature. These damages significantly influenced one another and the creep rupture time.
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Hu, Ping, Ran Tao, Xiaole Li, and Gilles Lubineau. "Decomposing the coupling damage in mode I multidirectional delamination." Composites Science and Technology 229 (October 2022): 109684. http://dx.doi.org/10.1016/j.compscitech.2022.109684.
Повний текст джерела
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Sivashanker, S. "Damage propagation in multidirectional composites subjected to compressive loading." Metallurgical and Materials Transactions A 32, no. 1 (January 2001): 171–82. http://dx.doi.org/10.1007/s11661-001-0113-y.
Повний текст джерела
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Liu, Yinghonglin, Jiang Peng, Wei Li, Chang Yang, Ping Sun, and Xiaowei Yan. "Predicting the Delamination Mechanisms of Multidirectional Laminates Using the Energy Release Rate Obtained from AE Monitoring." Materials Evaluation 80, no. 1 (January 1, 2022): 34–47. http://dx.doi.org/10.32548/10.32548/2022.me-04254.
Повний текст джерелаАнотація:
This study investigates delamination damage mechanisms during the double cantilever beam standard test using the strain energy release rate. The acoustic emission parameter is used to replace the original calculation method of measuring crack length to predict delamination. For this purpose, 24-layer glass/epoxy multidirectional specimens with different layups, and interface orientations of 0°, 30°, 45°, and 60°, were fabricated based on ASTM D5528 (2013). Acoustic emission testing (AE) is used to detect the damage mechanism of composite multidirectional laminates (combined with microscopic real-time observation), and it is verified that the strain energy release rate can be used as a criterion for predicting delamination damage in composite materials. By comparing the AE results with the delamination expansion images observed by microvisualization in real time, it is found that the acoustic emission parameters can predict the damage of laminates earlier. Based on the data inversion of the acoustic emission parameters of the strain energy release rate, it is found that the strain energy release rate of the specimens with different fiber interface orientations is consistent with the original calculated results.
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Liu, Yinghonglin, Peng Jiang, Wei Li, Chang Yang, Ping Sun, and Xiaowei Yan. "Predicting the Delamination Mechanisms of Multidirectional Laminates Using the Energy Release Rate Obtained from AE Monitoring." Materials Evaluation 80, no. 1 (January 1, 2022): 34–47. http://dx.doi.org/10.32548/2022.me-04254.
Повний текст джерелаАнотація:
This study investigates delamination damage mechanisms during the double cantilever beam standard test using the strain energy release rate. The acoustic emission parameter is used to replace the original calculation method of measuring crack length to predict delamination. For this purpose, 24-layer glass/epoxy multidirectional specimens with different layups, and interface orientations of 0°, 30°, 45°, and 60°, were fabricated based on ASTM D5528 (2013). Acoustic emission testing (AE) is used to detect the damage mechanism of composite multidirectional laminates (combined with microscopic real-time observation), and it is verified that the strain energy release rate can be used as a criterion for predicting delamination damage in composite materials. By comparing the AE results with the delamination expansion images observed by microvisualization in real time, it is found that the acoustic emission parameters can predict the damage of laminates earlier. Based on the data inversion of the acoustic emission parameters of the strain energy release rate, it is found that the strain energy release rate of the specimens with different fiber interface orientations is consistent with the original calculated results.
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Athanasopoulos, N., and V. Kostopoulos. "Damage detection via Joule effect for multidirectional carbon fiber reinforced composites." Applied Physics Letters 101, no. 11 (September 10, 2012): 114109. http://dx.doi.org/10.1063/1.4751992.
Повний текст джерелаДисертації з теми "Multidirectional damage"
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Singh, Chandra Veer. "Multiscale modeling of damage in multidirectional composite laminates." Thesis, [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2312.
Повний текст джерела
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Angelidis, Nikolaos. "Damage sensing in CFRP composites using electrical potential techniques." Thesis, Cranfield University, 2004. http://dspace.lib.cranfield.ac.uk/handle/1826/127.
Повний текст джерелаАнотація:
This Thesis investigates the damage sensing capabilities of the electrical potential measurement technique in carbon fibre reinforced polymer composites. Impact damage was introduced in multidirectional laminates and its effect on potential distribution studied. It was found that delaminations and fibre breakages within the laminate can be detected and located by measuring potential changes on the external composite surface. The extent and size of potential changes were significantly affected by the position of the current electrodes in relation to the potential measurement probes. A numerical model was developed investigating the effect of different size delaminations, located in various positions within the lamina, on electrical potential distributions on the external ply, and a quantitative analysis of the numerical results is presented. The numerical simulations demonstrated that the measured potential changes on the external ply were in proportion to the delamination size. The numerical and experimental results were compared and the optimum configuration of current electrodes and potential probes for damage detection selected. The response of electrical potential to mechanical strain, in unidirectional and multidirectional samples was also investigated. It was found that the conductive medium, used for introducing the current, defines the piezo-resistance performance of the composite. A finite element model was developed able to predict the effect of inhomogeneous current introduction in unidirectional specimens on electrical potential and piezo-resistance. The effects of temperature and water absorption on potential measurements were also presented.
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TESEI, CLAUDIA. "Nonlinear analysis of masonry and concrete structures under monotonic and cyclic loading: a regularized multidirectional d+/d− damage model." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2710141.
Повний текст джерелаАнотація:
A rigorous structural analysis is fundamental in the safety assessment of the built heritage and in its efficient conservation and rehabilitation. In line with the necessity of refined techniques, the objective of the present thesis is to develop and validate, in a displacement-based finite element framework, a nonlinear model apt for the study of masonry and concrete structures under monotonic and cyclic loading.
The proposed constitutive law adopts two independent scalar damage variables, d+ and d−, in combination with the spectral decomposition of the elastic strain tensor, to simulate the pronounced dissimilar response under tension and compression, typical of these materials. The assumption of energy-equivalence between the damaged solid and the effective (undamaged) one is considered for representing the orthotropy induced in the material by the degradation process, with the consequence that a thermodynamically consistent constitutive operator, positive definite, symmetric and strain-driven, is derived.
The formulation is integrated with a multidirectional damage procedure, addressed to extend the microcrack closure-reopening (MCR) capabilities to generic cyclic conditions, especially shear cyclic conditions, making the model suitable for dealing with seismic actions. Maintaining unaltered the dependence of the constitutive law from d+ and d−, this approach activates or deactivates a tensile (compressive) damage value on the base of the current maximum (minimum) principal strain direction. In correspondence with damage activation (crack opening) or deactivation (crack closure), a smooth transition is introduced, in order to avoid abrupt changes in stiffness and enhance the numerical performance and robustness of the multidirectional procedure.
Moreover, the mesh-objectivity of the numerical solutions is ensured by resorting to a nonlocal regularization technique, based on the adoption of damage variables driven by an averaged elastic strain tensor. To perform the averaging of the strain tensor, an internal length lRG is considered in the continuum. The strategy chosen to define the parameters affecting the softening behaviour consists in the modification of the local softening law on the base of the internal length, with the intent of ensuring the proper evaluation of the correct fracture energy Gf.
The adequacy of the proposed constitutive model in reproducing experimental results is proven for both monotonic and cyclic loading conditions. Under monotonic loads, unreinforced concrete notched elements subjected to pure tension, pure bending and mixed-mode bending are studied. The two examples of application involving cyclic loads, a masonry and a reinforced concrete wall under in-plane cyclic shear, constitute a validation of the multidirectional damage approach, showing how the suitable representation of unilateral effects and permanent deformations is essential to model the observed structural response in terms of maximum resistance and dissipation capacity.
The effectiveness of the regularized damage formulation is proven by successfully studying a masonry arch and reinforced and unreinforced concrete elements. Besides the validation of the numerical results with experimental or analytical data, each application is exploited to highlight one or more features of the formulation: the mesh-size and mesh-bias independence of the results, the effect of the choice of the variable to be averaged, the possibility to reproduce structural size effects, the influence of the internal length lRG. On this latter aspect, the almost null dependence of the regularized solutions on the internal length in terms of force-displacement curves, achieved thanks to the calibration strategy adopted to define the energy dissipation, suggests the interpretation of the internal length as a regularization parameter. On the one hand, this implies an analogy between the role played by the nonlocal internal length in a nonlocal model and the one’s of the mesh size in the crack band approach (Bažant and Oh, 1983). On the other hand, this translates in the versatility of the regularized damage model, which requires only the identification of the standard material properties (elastic constants, fracture energies and strengths).
Finally, the d+/d− damage model is successfully applied to the study of a three-span masonry arch bridge subjected to a concentrated vertical load, in order to evaluate its carrying capacity and its failure mechanism. Numerical issues, usually neglected in large-scale applications, are also addressed proving the reliability of the regularized approach to provide mesh-independent results and its applicability.
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Birur, Anand. "Time-dependent damage evolution in multidirectional polymer matrix composite laminates." 2008. http://hdl.handle.net/1993/3035.
Повний текст джерелаАнотація:
Multi-directional polymer matrix composite materials are increasingly used in load-bearing structural applications ranging from primary aircraft structures and automotive parts to rehabilitation of bridges. Long-term durability, characterized by time-dependent degradation in strength (known as creep-rupture) and modulus (known as creep), is an important concern in these applications. Despite the experimental evidence on the influence of time-dependent damage on creep and creep rupture of multi-directional composites, current level of understanding of this is very limited. Hence, the focus of this thesis is to develop a clear understanding of the time dependent evolution of various damage modes and their influence on creep rupture of polymer matrix composite laminates.Three laminates [0/90/0], [±45/902]s, and [0/902]s were subjected to a wide range of constant stresses at various test temperatures and creep rupture time was recorded.The various damage modes that developed, with stress during tensile testing, and with time during constant stress creep rupture testing were transverse cracking, vertical cracking, delamination, vertical splitting and fiber fracture.The appearance of these damages were time dependent confirming that the FPF stress is time-dependent, while the conventional wisdom is to consider it to be time-independent in design. Beyond FPF, the damage continued to evolve for a certain period of time beyond which additional damage modes started to evolve influencing the evolution rate of one-another.The percentage of creep rupture time during which a single mode of damage was evolving decreased with increase in applied stress and test temperature.Based on these results it is concluded that creep rupture of multidirectional laminates is influenced by contributions from a complex interaction of various damage modes that evolve with time, suggesting that creep rupture predictions could be good approximations only.May 2008
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Asadi, Amir. "A model for time-independent and time-dependent damage evolution and their influence on creep of multidirectional Polymer composite laminates." 2013. http://hdl.handle.net/1993/21681.
Повний текст джерелаАнотація:
Application of polymer matrix composites in engineering structures has been steadily increasing over the past five decades. Multidirectional polymer composites are one class of continuous fiber reinforced polymer matrix composites used in aerospace structures, where the desired mechanical performance outweighs the cost. Their modulus and strength degrade with time (known as creep and creep rupture) during the service, owing to the viscos-elasticity of the polymer matrix. Additional contribution to this degradation comes from various damage modes developed in the plies of the composite with time and identified in this thesis as TDD (Time Dependent Damage). These damage modes may also develop due to process-induced residual stresses, and during loading to the service load, identified as TID (Time Independent Damage). TID influences the TDD, the creep and the creep rupture. The objective of this thesis is to develop a model to predict the evolution of TID and TDD in multiple plies of a laminate and their influence on creep. The predominant damage mode, transverse cracking, is modeled in this study. The model consists of four modules, PIS, QSL, SL, and VA. The PIS, QSL, and SL moduli predict changes in ply stresses for incremental change in temperature, stress, and time respectively, using lamination theory and assuming linear elastic behavior of the plies during an incremental step. In parallel, each module predicts the stored elastic energy in each ply after each incremental step and compares it with a critical stored elastic energy criterion to determine if a ply would crack. If fracture is predicted, the VA module based on variational analysis, is invoked to determine the crack density and the perturbation in ply stresses due to cracking. The perturbation stresses are used by the module that invoked the VA module to determine the ply stresses after cracking during the current incremental step. The model predictions for a [±45/90]s laminate, at two test temperatures (80C and 180C) and four stresses in the range of 20–54 MPa, compare very well with experimental results validating the model.
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Behbahani, Ali Edalat. "Constitutive models to simulate failure of structures made by cement based materials." Doctoral thesis, 2017. http://hdl.handle.net/1822/46013.
Повний текст джерелаАнотація:
Tese de Doutoramento - Plano de tese no âmbito do Programa Doutoral em Engenharia CivilNonlinear Finite Element Analysis (NFEA) has been widely adopted as an effective and reliable method to analyze reinforced concrete (RC) structures subjected to various loading scenarios. Amongst many key factors that affect the reliability of a NFEA tool used for analysing RC structures, the selected constitutive model still remains the foremost challenging task due to the complexity of concrete behaviour associated to the cracking in tension and crushing in compression. The present work proposes a new constitutive model for cement based materials, allowing the possibility of simulating the complex functioning of concrete under both tension and compression. The model proposes a unified approach combining a multidirectional fixed smeared crack model to simulate the crack initiation and propagation with a plastic-damage model to account for the inelastic compressive behaviour of concrete between cracks. The smeared cracking model considers the possibility of forming several cracks in the same integration point, whose orientations, conditioned by an adopted criterion, are however preserved constant during the cracking process. The crack initiation is governed by the Rankine failure criterion, whereas the crack propagation (crack opening process) is simulated by a trilinear (or a quadrilinear) softening diagram. Two approaches are available to simulate the fracture mode II: one based on the concept of shear retention factor, and the other one on a shear softening diagram that requires some information about the fracture mode II propagation. The plasticity model is defined by four entities: yield function (yield surface); flow rule; evolution law for the hardening variable; and condition for defining loading–unloading process. Evolution of the yield surface during the plastic flow is governed by a single hardening parameter for compression. The plasticity part is responsible for simulating irreversible strains and volumetric strain in compression, whereas the strain softening and stiffness degradation of the material under compression are simulated by a strain based isotropic damage model. In this damage approach the state of damage in concrete under compression is equally distributed in all directions, and can be represented by a scalar damage parameter. Calculation of the scalar damage parameter is an explicit operation as this parameter is driven by the plastic hardening parameter. Two versions of the model are developed, one dedicated to concrete structures subjected to plane stress fields, and the second for being applied to concrete structures submitted to three dimensional stress states. Both versions of the model are implemented into FEMIX 4.0 computer program. To appraise the performance of the model and to evidence the interaction between cracking and plasticity-damage parts of the model, some numerical tests at material level are executed, and the obtained results are discussed. The model appraisal at the structural level is also considered. The set of experimental tests simulated in this thesis covers a wide range of specimens regarding geometry, concrete type, loading configurations, and reinforcement conditions, in order to demonstrate the robustness of the developed model. These structures are of particular interest for the assessment of the reliability of the model, since in these examples the failure mechanism involved simultaneous occurrence of cracking and inelastic deformation in compression. The predictive performance of the model in terms of load carrying capacity, ductility, crack pattern, plastic zones, and failure modes is obtained by comparing the results of the numerical simulations and the available experimental data.
O método dos elementos finitos (MEF) tem-se revelado eficaz na análise não linear de estruturas de betão armado submetidas a diferentes tipos de carregamentos. De entre os muitos fatores que podem afetar a fiabilidade de uma ferramenta capaz de efetuar uma análise não linear usando o MEF, o modelo constitutivo selecionado ainda continua a ser o desafio mais importante, nomeadamente devido à complexidade do comportamento do betão associado à fendilhação quando sujeito a tração e ao esmagamento em compressão. O presente trabalho propõe um novo modelo constitutivo, capaz de simular o comportamento complexo de materiais de matriz cimentícia quando sujeitos a esforços de tração e de compressão. O modelo propõe uma abordagem unificada, combinando um modelo de múltiplas fendas fixas distribuídas que permite simular o início de fendilhação e a sua propagação com um modelo de dano e plasticidade para simular o comportamento inelástico do betão entre fendas. O modelo de fendilhação permite a formação de várias fendas por ponto de integração, cuja orientação é condicionada por um determinado critério e preservada constante durante o processo de fendilhação. A abertura de fenda é condicionada pelo critério de Rankine, sendo o seu desenvolvimento simulado por intermédio de um diagrama de amolecimento trilinear ou quadrilinear. Duas abordagens estão disponíveis para simular o modo II de fratura: uma baseada no conceito de fator de retenção ao corte, e o outro utilizando um diagrama de amolecimento definido com base nos parâmetros do modo II de fractura. O modelo de plasticidade é definido: pela função de cedência (superfície de cedência); lei de escoamento plástico; lei de endurecimento; condição para a definição do processo de carga e descarga. A evolução da superfície de cedência durante o escoamento plástico é governada por um único parâmetro de endurecimento. A parte da plasticidade é responsável por simular as deformações irreversíveis e a deformação volumétrica em compressão, enquanto o amolecimento e a degradação da rigidez do material sob compressão são simulados por um modelo de dano isotrópico. Nesta abordagem, o estado de dano no betão sob compressão é igualmente distribuído em todas as direções, e pode ser representado por um escalar denominado parâmetro de dano. O modelo proposto é desenvolvido numa primeira fase para estados planos de tensão e posteriormente generalizado para estados de tensão tridimensionais. Estas duas versões do modelo foram integradas no código computacional denominado FEMIX 4.0. De forma a evidenciar as partes do modelo que têm em conta a simulação da propagação da fendilhação, do dano e da plasticidade, bem como da sua interação, são executados alguns testes numéricos focados no comportamento do material, sendo os seus resultados discutidos. Os ensaios experimentais escolhidos para avaliar a robustez do modelo a nível estrutural abrangem uma ampla gama de elementos no que respeita a geometria, tipo de betão, configurações de carga e de reforço. Estas estruturas são de particular interesse para a avaliação da fiabilidade do modelo, uma vez que nestes exemplos ocorrem simultaneamente fendilhação e deformação plástica em compressão. O desempenho do modelo em termos de previsão da capacidade de carga, da ductilidade, do padrão de fendilhação, das zonas plásticas e dos modos de rutura é obtido comparando os resultados das simulações numéricas com os dos ensaios experimentais disponíveis.
The research reported in the present thesis is carried out at the Department of Civil Engineering of University of Minho. The financial supports provided by the research projects “PREPAM” with reference number of PTDC/ECM/114511/2009, and “SlabSys- HFRC”, with reference PTCD/ECM/120394/2010, both supported by the Portuguese Foundation for Science and Technology (FCT), are gratefully acknowledged.
Частини книг з теми "Multidirectional damage"
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Ruiz-Iglesias, R., G. Ólafsson, O. T. Thomsen, and J. M. Dulieu-Barton. "Identification of Subsurface Damage in Multidirectional Composite Laminates Using Full-Field Imaging." In Thermomechanics & Infrared Imaging, Inverse Problem Methodologies and Mechanics of Additive & Advanced Manufactured Materials, Volume 6, 39–42. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-17475-9_6.
Повний текст джерела
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Montesano, John, and Farzad Sharifpour. "Modelling damage evolution in multidirectional laminates: micro to macro." In Multi-Scale Continuum Mechanics Modelling of Fibre-Reinforced Polymer Composites, 463–507. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-818984-9.00016-0.
Повний текст джерела
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Jayaraman, Raghavan. "Time-dependent damage evolution in unidirectional and multidirectional polymer composite laminates." In Creep and Fatigue in Polymer Matrix Composites, 303–21. Elsevier, 2019. http://dx.doi.org/10.1016/b978-0-08-102601-4.00010-2.
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Sanchez-Sotelo, Joaquin. "Shoulder Instability and the Labrum." In Mayo Clinic Principles of Shoulder Surgery, 171–214. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190602765.003.0007.
Повний текст джерелаАнотація:
The glenohumeral joint architecture allows for a very ample range of motion. This same architecture, so beneficial for shoulder mobility, also makes the glenohumeral joint particularly prone to instability. Damage to the glenoid labrum is present in many patients with shoulder instability, although the complexity of the pathology involved in shoulder instability goes beyond labral tears. The rotator cuff and the biceps tendon, discussed in chapter 6, The Rotator Cuff and Biceps Tendon, are intimately involved with instability and the labrum; some of the concepts described in chapter 6 will apply here as well. This chapter covers shoulder instability and the labrum, including management of the acute glenohumeral joint dislocation, recurrent posterior instability and posterior labral tears, multidirectional instability, superior labral tears, failed instability surgery, and salvage procedures.
Тези доповідей конференцій з теми "Multidirectional damage"
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Schaff, J. R., and R. Y. Kim. "Damage Initiation and Progression in Multidirectional Laminates With a Hole." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1197.
Повний текст джерелаАнотація:
Abstract Holes are pervasive in load-bearing composite structures within the aerospace industry, as a result of the use of mechanical fasteners in assembly and cutouts to accommodate wiring and hydraulic lines. In this work, static loading experiments were conducted on composite laminates to document the initiation and growth of damage and to record changes in the strain field. The main objective of this work was the development of an experimental database for comparison with the results from a three-dimensional stress analysis based on spline variational theory. Two multidirectional laminates considered in this study were [0/90]2s and [±30/90]s of IM7/5250-4 (graphite fiber/toughened BMI). For each loading increment strains were recorded at a number of locations in close proximity to the hole as well as far field, and the specimen was subjected to x-radiography. Acoustic emission was also monitored during loading and compared to strains and radiographic images to identify damage initiation and progression. Experimental strains were well with the analytical strains at low loadings, prior to extensive damage development. The details of damage progression in these laminates discussed.
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Antoun, Tarabay H. "Simulation of a Spherical Wave Experiment in Marble Using a Multidirectional Damage Model." In SHOCK COMPRESSION OF CONDENSED MATTER - 2003: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter. AIP, 2004. http://dx.doi.org/10.1063/1.1780505.
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Daliri, Ali, Chun H. Wang, Sabu John, Amir Galehdar, Wayne S. T. Rowe, and Kamran Ghorbani. "Multidirectional Circular Microstrip Patch Antenna Strain Sensor." In ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/smasis2011-5065.
Повний текст джерелаАнотація:
In this paper, a new design for microstrip patch antenna strain sensors is proposed. The new antenna sensor works based on the meandered microstrip patch antennas. It is threefold more sensitive than previously proposed circular microstrip patch antenna strain sensors. Also, the overall physical dimension of the new antenna sensor is reduced by the factor of five. The current sensor is able to detect strain in all directions. In order to design the antenna sensor, two available commercial FEM software packages ANSYS™ and HFSS™ are used. Both experimental and FEM results corroborate the multidirectional feature of the new antenna sensor. Also, the effect of the hole size in the structure (for coaxial connection to the antenna) on the antenna performance has been studied. Based on the results obtained, the antenna sensor can be recommended for use in structural health monitoring for strain-based damage detection in aerospace structures.
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Montesano, John, and Chandra Veer Singh. "Development of a Synergistic Damage Mechanics-Based Model for Predicting Multiaxial Effects in Progressive Failure of Composite Structures." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38109.
Повний текст джерелаАнотація:
A major benefit of advanced fiber-reinforced polymer composites is that they can be tailored and optimized to suit a particular structural application by orienting the reinforcing fibers along multiple directions. For practical load-bearing structural components manufactured from multidirectional laminates, predicting their mechanical behaviour is quite complex. This is specifically the case for progressive failure analysis of these materials when subjected to quasi-static or fatigue loading since local cracks will initiate and evolve in multiple directions simultaneously. The difficulty of the problem increases further when these laminates are subjected to complex multiaxial stress states. This is due to the fact that the multidirectional crack state will be subjected to additional crack driving stress components, which will ultimately alter the crack evolution characteristics. A synergistic damage mechanics (SDM) methodology has recently been developed to address these issues in progressive damage analyses of composite laminates containing multiple damage modes and subjected to uniaxial loading [1]. By combining micromechanics and continuum damage mechanics, the SDM methodology provides a rigorous and practical tool for accurate prediction of progressive damage behaviour in composite structures. This is essential for accurately predicting the integrity and durability of practical structures, which will lead to safer and more efficient designs.
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Chaphalkar, Pramod, and Ajit O. Kelkar. "Semi-Analytical Modeling of Progressive Damage in Twill Woven Textile Composites." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/pvp-25212.
Повний текст джерелаАнотація:
Abstract Various alternative composite materials like, textile composites, especially woven, are being developed and tried in place of conventional multidirectional laminates, because they have better properties in mutually orthogonal directions and out of plane properties than the multidirectional laminates. In structural applications, predictions of the elastic modulii, Poisson’s ratios from the weave architecture and the properties of the constituents are required. There are various parameters that characterize the weave architecture of woven laminate composites. In repeated loading, the matrix cracking occurs, degrading matrix properties. This in turn degrades the effective properties of the woven composites. Analytical models are necessary to study the effects of these parameters on the behavior of woven fabric composites and to design efficient woven structure for particular application. The objective of the current paper is to study the effect of matrix cracking on the effective properties of the twill woven composites by degrading the matrix properties. First the effective properties of the composite material, without any matrix cracks, are determined by using an analytical model, which predicts the stiffness of the twill woven composites. This model takes into account effects of the actual fabric structure with various tow cross sections by considering tow undulations and continuity along both the fill and warp directions. In twill woven composites, there is a weaker matrix along with the stronger medium i.e. the glass fibers. The matrix first fails and then the load is transferred to the fibers. The matrix properties are degraded in the resin pockets and also in the transverse tows only. This is because normally matrix cracking first occurs in the transverse tows (cracks originate in the tows that run in the transverse direction to the loading). The degradation of the properties includes the Young’s Modulus and the Poisson’s ratio of the resin. With these modified properties of the resin, the homogeneous properties of the transverse tows are calculated. At each degradation step the effective properties of the composite material are evaluated. This progressive failure is continued till the matrix loses most of its strength.
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Kim, Ran Y., and G. P. Tandon. "In Situ Observation and Modeling of Damage Modes in Cross-Ply Ceramic Matrix Composites." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0699.
Повний текст джерелаАнотація:
Abstract Ceramic-matrix composites generally exhibit matrix and/or interface damage well before final failure because of the low strain capability of the brittle matrix and weak interfacial bonding. These damages have a significant influence on the stress-strain behavior as well as on the ultimate strength of the composite. The failure process in a multidirectional laminate is further complicated by its dependence on ply orientations and stacking sequence Reported in this paper are the results of both analytical and experimental investigations carried out in an attempt to understand the initiation and propagation of damage in a [0/90]3S cross-ply laminate. A glass-ceramic matrix composite reinforced with silicon carbide (Nicalon) fibers is investigated at room temperature under uniaxial tensile loading. The initiation and propagation of interfacial debonding, microcracking, and fiber breaks were observed in situ, under applied load using a specially built loading device. The observed damage modes were then incorporated into existing micromechanical models to predict the laminate stress-strain behavior and compared with the experimental measurements.
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CARRARO, PAOLO, SIMONETTO MIRKO, LUCIO MARAGONI, and MARINO QUARESIMIN. "DAMAGE EVOLUTION IN CROSS-PLY LAMINATES UNDER VARIABLE AMPLITUDE CYCLIC LOADINGS." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35891.
Повний текст джерелаАнотація:
Predicting the initiation and propagation of multiple off-axis cracks in multidirectional laminates under cyclic loadings is essential in a stiffness-driven design approach. Even under a constant amplitude cyclic load, the multiple crack initiation represents always an inherently variable amplitude (VA) problem. Indeed, the initiation of cracks causes a stress re-distribution so that each point in a laminate is subjected to a stress state that changes continuously during the fatigue life. At present, no models or experimental evidences on the crack initiation phenomenon under VA loadings are available in the literature. Crack density prediction models usually rely on a simple linear damage accumulation rule, even if its validity has not been proved yet. In this work, two types of fatigue tests were carried out on glass/epoxy cross-ply laminates under VA two-block loadings: 1) Initially, the number of cycles in the first block was chosen low enough to prevent the initiation of transverse cracks in the first block; then the load was changed and the crack initiation phenomenon was characterized in the second block. 2) Then, two block loadings were applied on other specimens, with a high enough number of cycles in the first block to promote the initiation of multiple cracks; the crack density evolution was thus characterized in both blocks. A model recently developed by the authors was applied to the experimental data, revealing the suitability of the linear damage accumulation rule under block loadings, at least from a phenomenological point of view.
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Vladova, A. "Identification Method of Oil Pipelines Technical Condition Based Upon Multigraph Models." In 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33429.
Повний текст джерелаАнотація:
The problem of technical condition identification of aging oil pipelines in Russian Federation and in the world is relevant, since a significant number of them have been in service for over 30 years. More and more of them are getting closer to running out of normative resources. Within a method for reducing the size of task of identifying the technical condition of oil pipelines there were created special types of multigraph models (MGM) with interval-valued states of geometric characteristic of metallic shell defects. Depending on oil pipelines operation time, the behavior of proposed models has been examined and operating performance with due account for technical condition identification has been determined, also the possibility of diminishing scope of inspections and repair works was shown. Multigraph models proposed here contain a set of states, which were singled out for the first time according to the analogue variable and are connected with multidirectional arcs with intensities of damage calculated on the relative amount of defects in the states.
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Micheal, Amany, Yehia Bahei-El-Din, and Mahmoud E. Abd El-Latief. "Designing Composites for Graceful Failure." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23039.
Повний текст джерелаАнотація:
Abstract When inevitable, failure in composite laminates is preferred to occur gracefully to avoid loss of property and possibly life. While the inherent inhomogeneity leads to slow dissipation of damage-related energy, overall failure is fiber-dominated and occurs in a rather brittle manner. Multidirectional plies usually give a more ductile response. Additionally, stiffness and strength as well as cost are important factors to consider in designing composite laminates. It is hence desirable to optimize for high mechanical properties and low cost while keeping graceful failure. Designing composite laminates with hybrid systems and layups, which permit gradual damage energy dissipation, are two ways proposed in this work to optimize for mechanical properties while avoiding catastrophic failure. In the hybrid system design, combining the less expensive glass reinforced plies with carbon reinforced plies offers a cost-effective product, marginal mechanical properties change and ductile profile upon failure. Hybrid glass/carbon composite laminates subjected to three-point bending showed strain to failure which is double that measured for carbon composite specimens, without affecting the ultimate load. Energy dissipation mechanisms were also created by building laminates which were intentionally made discontinuous by introducing cuts in the fibers of the interior plies. This created a longer path for damage before cutting through the next ply resulting in double failure strain with marginal reduction in load. The effect of fiber discontinuity in terms of spacing and distribution are among the factors considered.
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KAPLAN, HALIT, and TARIK OZKUL. "A NOVEL FATIGUE DAMAGE SENSOR FOR STRESS/STRAIN-LIFE BASED PREDICTION OF REMAINING FATIGUE LIFETIME OF LARGE AND COMPLEX STRUCTURES: AIRCRAFTS." In Structural Health Monitoring 2021. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/shm2021/36274.
Повний текст джерелаАнотація:
In this paper, a new novel smart fatigue damage sensor (US Patent 8,746,077 B2) for continuous monitoring of fatigue health state of structural members of aircrafts is presented. The sensor has multiple parallel beams, each sensitive to different levels of fatigue lifetime. These beams are designed to fail prematurely but progressively as the sensor goes through the same fatigue cycles as the structural member it is attached to. Whenever fatigue level on an individual beam of the sensor exceeds the number of engineered fatigue cycles, that particular beam fails and sensor electronics can detect that failure and transmit this information wirelessly. Just like mileage signs on the road informing you about the distance left to your destination as you drive, multiple beams of the sensor serve similar purpose informing the user about the distance to failure progressively. Just as mileage signs can be placed at desired intervals, multiple beams can be engineered to give indication at desired fatigue milestones. This gives ability to monitor aging status of the structure and also help schedule predictive maintenance accordingly. The beams inside the sensor are designed to work based on different stress concentration factors (Notch Factors)/geometry to measure the level of structural fatigue health. The sensor needs to be mounted on the surface of structural member at fatigue critical locations just like strain gauges. Unlike strain gauges, a unique feature of the new sensor is its ability to operate without power source. This way it can serve for a long time without maintenance. Since sensor does not need power to operate, it can be embedded or mounted on critical components including composite structures or rotating helicopter shafts, gears, etc. After being attached to critical location of the real structure, the smart fatigue damage sensor goes through the same fatigue life experience of critical structural elements or mechanical components from the beginning of service life to the end. The fatigue sensing beams with different stress-strain and fatigue lifetime levels are designed to estimate the fatigue damage accumulation and remaining fatigue life of unidirectional and multidirectional structural or mechanical elements including composite structures. Since distributed fatigue sensor network system monitors the fatigue health conditions of structures periodically or on demand, the collected data can be used not only for condition-based fatigue life prediction but also for sensor based predictive fatigue maintenance and development. This new approach could also pave way to new fatigue design tools for fatigue sensitive complex, large and expensive engineering structures or mechanical systems of aircraft structures. Full paper will be concentrating design principles of the sensor based on Stress/Strain-Life Based Prediction principles.