Pub Date : 2001-11-11DOI: 10.1115/imece2001/ad-25308
P. Dutta, D. Hui, Marta Argueso
An experimental study of the behavior at different temperatures of Balsa Wood Core Composite Sandwich (BWCCS) panels proposed to be used in shipboard structures is presented. It characterizes the high temperature failure of the BWCCS under a flexural load. The study includes two different experiments. The first is the determination of temperature distribution along the thickness of BWCCS panels. In the second, the panels are studied in a three-point bending test at two different temperatures: room temperature (20°C) and high temperature (79°C).
{"title":"Degradation Mechanism of the Balsa Wood Core Composite Sandwich Beam From Heating From One Side","authors":"P. Dutta, D. Hui, Marta Argueso","doi":"10.1115/imece2001/ad-25308","DOIUrl":"https://doi.org/10.1115/imece2001/ad-25308","url":null,"abstract":"\u0000 An experimental study of the behavior at different temperatures of Balsa Wood Core Composite Sandwich (BWCCS) panels proposed to be used in shipboard structures is presented. It characterizes the high temperature failure of the BWCCS under a flexural load. The study includes two different experiments. The first is the determination of temperature distribution along the thickness of BWCCS panels. In the second, the panels are studied in a three-point bending test at two different temperatures: room temperature (20°C) and high temperature (79°C).","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125348971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/ad-25324
M. Pindera, J. Aboudi, S. Arnold
A major failure mechanism in plasma-sprayed thermal barrier coatings is spallation of the top coat due to the top/bond coat thermal expansion mismatch concomitant with deposition-induced interfacial roughness, oxide film growth and creep-induced normal stress reversal at the rough interface’s crest. Reduction of the thermal expansion mismatch through the use of heterogeneous bond coats has been suggested to increase coating durability. This approach is examined using the higher-order theory for functionally graded materials. Specifically, combined effects of a graded bond coat microstructure and oxide film thickness on the crack-tip stress field in the vicinity of a rough top/bond coat interface are investigated during furnace-type thermal cycling in the presence of a local horizontal delamination situated within the homogeneous top coat at the rough interface’s crest. The analysis, which accounts for the creep/relaxation effects within the individual constituents, is conducted in two distinct ways. In the first approach, the bond coat’s heterogeneous microstructure is fully taken into account while in the second approach the bond coat’s microstructure is homogenized. The feasibility of using graded bond coat microstructures to reduce horizontal delamination driving forces is critically examined and the limitations of the homogenization-based approach are highlighted.
{"title":"Effects of Interfacial Roughness, Oxide Film Thickness and Heterogeneous Bond Coat Microstructure on Spallation Mechanism in Plasma-Sprayed TBCs","authors":"M. Pindera, J. Aboudi, S. Arnold","doi":"10.1115/imece2001/ad-25324","DOIUrl":"https://doi.org/10.1115/imece2001/ad-25324","url":null,"abstract":"\u0000 A major failure mechanism in plasma-sprayed thermal barrier coatings is spallation of the top coat due to the top/bond coat thermal expansion mismatch concomitant with deposition-induced interfacial roughness, oxide film growth and creep-induced normal stress reversal at the rough interface’s crest. Reduction of the thermal expansion mismatch through the use of heterogeneous bond coats has been suggested to increase coating durability. This approach is examined using the higher-order theory for functionally graded materials. Specifically, combined effects of a graded bond coat microstructure and oxide film thickness on the crack-tip stress field in the vicinity of a rough top/bond coat interface are investigated during furnace-type thermal cycling in the presence of a local horizontal delamination situated within the homogeneous top coat at the rough interface’s crest. The analysis, which accounts for the creep/relaxation effects within the individual constituents, is conducted in two distinct ways. In the first approach, the bond coat’s heterogeneous microstructure is fully taken into account while in the second approach the bond coat’s microstructure is homogenized. The feasibility of using graded bond coat microstructures to reduce horizontal delamination driving forces is critically examined and the limitations of the homogenization-based approach are highlighted.","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"35 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133105403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/ad-25312
R. Li, G. Kardomateas
The phenomena of delamination branching/kinking from the interface of general anisotropic bimaterials are investigated based on the elegant Stroh’s sextic formulism of dislocation theory in matrix notation. A set of compact form of Green’s functions for two kinds of dislocation — an interface dislocation and a dislocation in one medium of the bimaterial elastic solid is obtained. Using these Green’s functions, the whole delamination including the interface part and the part branching into either one of the dissimilar anisotropic materials is modeled as a continuous distribution of the two kinds of dislocations. An interesting observation from this method is that the traction along the dislocation line when the dislocation is inside one medium, mathematically has similar form as the traction on the interface surface due to an interface dislocation. Thus a non-homogeneous Hilbert problem with discontinuous coefficients for this anisotropic bimaterials is formulated and a general solution to this problem is obtained. Consequentially, a preferable value of the branching angle for a given pair of anisotropic bimaterial media can be obtained by maximizing the energy release rate of the kinking-cracked solid. The comparison of other approaches which have appeared in the literature are discussed.
{"title":"On Delamination Branching of Anisotropic Bimaterials","authors":"R. Li, G. Kardomateas","doi":"10.1115/imece2001/ad-25312","DOIUrl":"https://doi.org/10.1115/imece2001/ad-25312","url":null,"abstract":"\u0000 The phenomena of delamination branching/kinking from the interface of general anisotropic bimaterials are investigated based on the elegant Stroh’s sextic formulism of dislocation theory in matrix notation. A set of compact form of Green’s functions for two kinds of dislocation — an interface dislocation and a dislocation in one medium of the bimaterial elastic solid is obtained. Using these Green’s functions, the whole delamination including the interface part and the part branching into either one of the dissimilar anisotropic materials is modeled as a continuous distribution of the two kinds of dislocations. An interesting observation from this method is that the traction along the dislocation line when the dislocation is inside one medium, mathematically has similar form as the traction on the interface surface due to an interface dislocation. Thus a non-homogeneous Hilbert problem with discontinuous coefficients for this anisotropic bimaterials is formulated and a general solution to this problem is obtained. Consequentially, a preferable value of the branching angle for a given pair of anisotropic bimaterial media can be obtained by maximizing the energy release rate of the kinking-cracked solid. The comparison of other approaches which have appeared in the literature are discussed.","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133532605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/ad-25321
H. Abramovich
A new piezoelectric actuation mechanism for smart sandwich structures is investigated and its performances are compared with the traditional one, which is based on an induced bending moment This piezoelectric mechanism deals with inducing shear forces and it is the result of piezoelectric materials, which are constrained and poled perpendicular to the applied electric field direction (across the thickness). The three-coupled equations of motion of a general non-symmetric piezolaminated composite beam subjected to axial and lateral tractions with the new actuation mechanism are derived. The displacement field is based on a first order shear deformation theory. The static case is investigated for continuous piezoelectric layers and for piezoelectric patches embedded into the carrying beam. Closed form solutions for the bending angle and the axial and lateral displacements along the beam are presented for various configurations of lay-up, boundary conditions and lateral tractions.
{"title":"Piezoelectric Actuation for Smart Sandwich Structures: Closed Form Solutions","authors":"H. Abramovich","doi":"10.1115/imece2001/ad-25321","DOIUrl":"https://doi.org/10.1115/imece2001/ad-25321","url":null,"abstract":"\u0000 A new piezoelectric actuation mechanism for smart sandwich structures is investigated and its performances are compared with the traditional one, which is based on an induced bending moment This piezoelectric mechanism deals with inducing shear forces and it is the result of piezoelectric materials, which are constrained and poled perpendicular to the applied electric field direction (across the thickness).\u0000 The three-coupled equations of motion of a general non-symmetric piezolaminated composite beam subjected to axial and lateral tractions with the new actuation mechanism are derived. The displacement field is based on a first order shear deformation theory. The static case is investigated for continuous piezoelectric layers and for piezoelectric patches embedded into the carrying beam. Closed form solutions for the bending angle and the axial and lateral displacements along the beam are presented for various configurations of lay-up, boundary conditions and lateral tractions.","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132868964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/ad-25326
L. Xie, Y. Sohn, E. Jordan, M. Gell
Photo-stimulated luminescence piezo-spectroscopy (PLPS) is being developed as a non-destructive technique for thermal barrier coatings (TBC). In this study, the evolution of photo-stimulated luminescence with 1 hour at 1121 °C thermal cycling was systematically investigated from the thermally grown oxide (TGO) in a production TBC system which consists of electron beam physical vapor deposited 7wt% Y2O3-ZrO2, (Ni,Pt)Al bond coat and CMSX-4 superalloy substrate. The change of compressive stress in the TGO layer with thermal cycling was calculated from the wavelength shift of luminescence spectrum. It consists of an increase from 1.5 to 2.5 Gpa at as received state to 2.5 to 3.5 Gpa at 10 cycles, a gradual decrease to 1.0 to 2.0 Gpa until 500 cycles, then a plateau at this level until TBC spallation. Some other information, such as change of peak width and relative intensity of R1 and R2 peak with thermal cycling, was also analyzed. The Physical basis of the photo-stimulated luminescence evolution was examined using scanning electron microscopy (SEM).
{"title":"Photo-Stimulated Luminescence Piezo-Spectroscopy Measurement on a EB-PVD 7YSZ/(Ni, Pt)Al/CMSX-4 TBC System","authors":"L. Xie, Y. Sohn, E. Jordan, M. Gell","doi":"10.1115/imece2001/ad-25326","DOIUrl":"https://doi.org/10.1115/imece2001/ad-25326","url":null,"abstract":"\u0000 Photo-stimulated luminescence piezo-spectroscopy (PLPS) is being developed as a non-destructive technique for thermal barrier coatings (TBC). In this study, the evolution of photo-stimulated luminescence with 1 hour at 1121 °C thermal cycling was systematically investigated from the thermally grown oxide (TGO) in a production TBC system which consists of electron beam physical vapor deposited 7wt% Y2O3-ZrO2, (Ni,Pt)Al bond coat and CMSX-4 superalloy substrate. The change of compressive stress in the TGO layer with thermal cycling was calculated from the wavelength shift of luminescence spectrum. It consists of an increase from 1.5 to 2.5 Gpa at as received state to 2.5 to 3.5 Gpa at 10 cycles, a gradual decrease to 1.0 to 2.0 Gpa until 500 cycles, then a plateau at this level until TBC spallation. Some other information, such as change of peak width and relative intensity of R1 and R2 peak with thermal cycling, was also analyzed. The Physical basis of the photo-stimulated luminescence evolution was examined using scanning electron microscopy (SEM).","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114303437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2001-11-11DOI: 10.1115/imece2001/ad-25317
T. Hause, L. Librescu
This paper addresses the problem of the dynamic response in bending of flat sandwich panels exposed to time-dependent external pulses. The study is carried out in the context of an advanced model of sandwich structures that is characterized by anisotropic laminated face sheets and an orthotropic core layer. A detailed analysis of the influence of a large number of parameters associated with the particular type of pressure pulses, panel geometry, fiber orientation in the face sheets and, presence of tensile uni/biaxial edge loads is accomplished, and pertinent conclusions are outlined.
{"title":"Dynamic Response of Sandwich Anisotropic Flat Panels to Explosive Pressure Pulses","authors":"T. Hause, L. Librescu","doi":"10.1115/imece2001/ad-25317","DOIUrl":"https://doi.org/10.1115/imece2001/ad-25317","url":null,"abstract":"\u0000 This paper addresses the problem of the dynamic response in bending of flat sandwich panels exposed to time-dependent external pulses. The study is carried out in the context of an advanced model of sandwich structures that is characterized by anisotropic laminated face sheets and an orthotropic core layer. A detailed analysis of the influence of a large number of parameters associated with the particular type of pressure pulses, panel geometry, fiber orientation in the face sheets and, presence of tensile uni/biaxial edge loads is accomplished, and pertinent conclusions are outlined.","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114554250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A Multi-Factor-Interaction-Model (MFIM) is briefly described to represent complex point material behavior in a single equation. The model is of product form in order to represent coupled interactions and to be computationally effective. The model describes a continuum or surface in space that represents the complex material behavior in terms of the various factors that affect a specified material behavior. The material specified behavior is inclusive of all material properties, mechanical, thermal, physical and effects thereon, such as temperature, time, cyclic loadings, etc. Sample cases results simulated by using MFIM are compared with test data to illustrate its versatility and its relevance to reality. These results show the MFIM can accurately predict metal matrix composite fatigue data and mechanical properties of a steel alloy. MFIM predicted results for the damage tolerance of a large shell made from structural steel subjected to internal pressure. Helpful guidelines for its effective use are also included.
{"title":"A Multi-Factor Interaction Model (MFIM) for Damage Initiation and Progression","authors":"C. Chamis","doi":"10.2495/MC110101","DOIUrl":"https://doi.org/10.2495/MC110101","url":null,"abstract":"\u0000 A Multi-Factor-Interaction-Model (MFIM) is briefly described to represent complex point material behavior in a single equation. The model is of product form in order to represent coupled interactions and to be computationally effective. The model describes a continuum or surface in space that represents the complex material behavior in terms of the various factors that affect a specified material behavior. The material specified behavior is inclusive of all material properties, mechanical, thermal, physical and effects thereon, such as temperature, time, cyclic loadings, etc. Sample cases results simulated by using MFIM are compared with test data to illustrate its versatility and its relevance to reality. These results show the MFIM can accurately predict metal matrix composite fatigue data and mechanical properties of a steel alloy. MFIM predicted results for the damage tolerance of a large shell made from structural steel subjected to internal pressure. Helpful guidelines for its effective use are also included.","PeriodicalId":442756,"journal":{"name":"Damage Initiation and Prediction in Composites, Sandwich Structures and Thermal Barrier Coatings","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122807174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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