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2. Effects of Buckling on Crack Propagation in Paper - a Stochastic Modelling Experiment
- Author
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International Paper Physics Conference (2007 : Gold Coast, Qld.), Skjetne, Bjorn, Helle, Torbjorn, and Hansen, Alex
- Published
- 2007
3. Significant improvement of thermal and tribological performance with polyimide as the matrix of paper‐based friction materials.
- Author
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Tian, Haochen, Fei, Jie, Li, Chang, Qi, Lehua, Cai, Xiaohang, Li, Bo, and Fu, Yewei
- Subjects
- *
FRICTION materials , *PHENOLIC resins , *MECHANICAL wear , *FRACTURE mechanics , *WEAR resistance - Abstract
Paper‐based friction materials with phenolic resin as the matrix are prone to thermal damage under harsh working conditions easily leading to materials failure. To satisfy the requirements of high speed and heavy load service situations, paper‐based friction materials with different polyimide resin content were prepared by wet forming technology to reveal the effect of polyimide resin on the properties of composites. And a paper‐based composite with phenolic resin was used for comparison. Results show that compared with the phenolic composite, tensile strength, and shear strength of the polyimide composite were increased by 50.5% and 36.4%, respectively. Due to the strong hydrogen bond in the imide ring of polyimide, the temperature of the polyimide composite at 2% weight loss was 292.7°C, which was 106.3°C higher than that of the phenolic composite. Moreover, the wear rate was reduced by 30.3% because the friction transfer film was produced during friction. To sum up, polyimide resin has the potential to replace phenolic resin under the condition of high speed and heavy load. Besides, the composite with polyimide resin content of 40.0 wt% demonstrated the best wear resistance and considerable strength attributed to the best interface combination. This research lays a theoretical foundation for the application of polyimide resin to paper‐based friction materials. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Application of the Acoustic Emission Method to Ranking Fatigue Damage in the Material of the Trunnions of Drying Cylinders in Cardboard- and Paper-Making Machines.
- Author
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Rastegaev, I. A., Khrustalev, A. K., Danyuk, A. V., Afanas'yev, M. A., Merson, D. L., Sevast'yanov, D. V., Melent'ev, S. V., and Plyusnin, A. D.
- Subjects
- *
FRACTURE mechanics , *MATERIAL plasticity , *ACOUSTIC emission , *FATIGUE cracks , *CYCLIC loads , *METAL fatigue , *FRICTION - Abstract
Using the example of assessing the technical condition of the trunnions of drying cylinders in cardboard machines (CBM), the question of the possibility of ranking cyclically loaded elements of dynamic equipment according to the degree of damage to their material by fatigue cracks using acoustic emission (AE) measurements is discussed. As a result of special laboratory studies with varying loads in the cycle of loading and lubrication of crack edges, the features of AE due to the friction of crack edges and plastic deformation at the crack tip during its growth in a viscous material have been established. It is shown that during cyclic loading of the material, AE signals from the friction of its banks are detected more steadily than AE signals due to a crack jump with an increase in its length, and that tracking the former ensures the detection of fatigue damage in the material even under loading conditions insufficient for crack growth. Based on the data obtained, three AE signs of the presence of fatigue damage in the material of the elements of dynamic equipment were developed under the condition of cyclic activation of the movement of crack edges. As a result of industrial testing of the developed AE signs, their operability was confirmed, their boundary values on the operating trunnions of CBM drying cylinders were clarified, and a method for ranking trunnions by the level of damage due to fatigue cracks was proposed. By comparing the results of AE measurements with ultrasound testing, the reliability of the proposed approach was evaluated and showed the probability of detecting a fatigue crack in the trunnions of CBM drying cylinders at the level of 71%, with the probability of skipping and false rejection of the product of 12 and 17%, respectively. The developed technique is also transferable to other massive dynamic equipment after clarifying the boundary values of AE signs of fatigue damage in the material on this type of facilities. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Enhancing structural analysis efficiency: a comprehensive review and experimental validation of advanced submodeling techniques, introducing the submodeling-density-shape-element removal (S-D-S-ER) method
- Author
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Teke, Ibrahim T. and Ertas, Ahmet H.
- Published
- 2024
- Full Text
- View/download PDF
6. Ink-lift-off during offset printing: a novel mechanism behind ink–paper coating adhesion failure.
- Author
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Kamal Alm, Hajer, Ström, Göran, Schoelkopf, Joachim, and Gane, Patrick
- Subjects
- *
OFFSET printing , *PAPER coatings , *ADHESION , *FRACTURE mechanics , *SURFACES (Physics) - Abstract
This paper reports on a special pilot coating and industrial printing trial designed to gain fundamental knowledge on ink adhesion failure on coated papers. We found that ink adhesion failure resulted in white spots without ink on the paper, referred to as uncovered areas and these spots gave print mottle problems. The white spots were due to two fundamentally different types of ink adhesion failure. One is the well-known ink rejection, which simply means that ink is not transferred to the surface. The other is a new type of ink adhesion failure, confirming a previous hypothesis suggested from laboratory observations. We refer to this as ink-lift-off adhesion failure, meaning that ink initially deposited on the paper surface becomes lifted off from the surface in a subsequent print unit. Adhesion failure by this mechanism was seen to occur more frequently than failure due to the well-known ink rejection. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
7. Identifying the weak spots in packaging paper: local variations in grammage, fiber orientation and density and the resulting local strain and failure under load.
- Author
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Lahti, Jussi, Dauer, Michael, Keller, D. Steven, and Hirn, Ulrich
- Subjects
FRACTURE mechanics ,DENSITY ,TENSILE tests ,FIBER orientation ,ENERGY dissipation ,REGRESSION analysis - Abstract
Measured local paper structure—i.e. local basis weight, local thickness, local density and local fiber orientation—has been linked to local strain and local material failure (local temperature increase due to energy dissipation upon fiber–fiber bond failure) measured during tensile testing. The data has been spatially linked through data map registration delivering several thousand 1 × 1 mm 2 paper regions, each containing all measured properties. The relation between local paper structure and resulting local deformation and failure is studied with regression models. Multiple linear regression modeling was used to identify the paper structure related drivers for local concentrations of strain under load and local concentrations of material failure, which are both starting to occur considerably before rupture of the paper. Analyzing the development of local strain in paper we found that regions with higher basis weight and higher fiber orientation in load direction tend to exhibit considerably lower strain during tensile testing. Furthermore, the relation between local strain and local grammage can be predicted with the statistical theory of elasticity. Also regions with higher density have lower local strain, but not as pronounced. The findings for local fiber–fiber bond failure of paper are similar but not equivalent. The strongest correlation exists with local grammage. Local density and local fiber orientation show in turn weaker correlation with local bond failure. Local variations in paper thickness were not relevant in any case. These findings are highlighting the relevance of local fiber orientation and local density variations as structural mechanisms governing paper failure. In the past the focus has been mostly on paper formation. Together with local grammage (formation) they are responsible for the weak spots in paper, and thus cause local concentrations of paper strain and the initiation of failure under tensile load. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
8. An Efficient Mixed-Mode Brittle Fracture Experiment Using Paper
- Author
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Flores, Mark and Xu, L. Roy
- Published
- 2013
- Full Text
- View/download PDF
9. Flexible paper-based composites with photothermal conversion and superhydrophobic properties.
- Author
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Guo, Qiyu, Wan, Jinming, Song, Chenying, Li, Hailong, and Hu, Jian
- Subjects
PHOTOTHERMAL conversion ,SURFACE preparation ,CONTACT angle ,FRACTURE mechanics ,ICE prevention & control ,PACKAGING materials - Abstract
Biofiber is an extensive and renewable raw material, whose products meet the demands of constructing an environmental-friendly and resource-favorable society. As a typical biofiber assembly, paper inherits its characteristics and may lose its mechanical properties after prolonged contact with water, leading to a material failure. Here, we report an environment friendly waterproof composite by a simple surface treatment. This composite is creatively prepared via a formation of rough microstructures for ink micro-aggregates on the ink-brushed paper, of which this bio-inspired structure is beneficial to hydrophobic properties and light capture capability. Specifically, it possesses excellent hydrophobicity with a high contact angle over 150° and photothermal performance with a solar evaporation rate of 1.324 kg m
−2 h−1 under 100 mW/cm2 . In addition, it reveals superior waterproof and deicing performance, decreasing the icing adhesion time to 63 s under 100 mW/cm2 . Additional advantages include durability, designability, and large-area production. In view of these excellent properties, this waterproof photothermal material holds a bright prospect in the fields of solar evaporation, deicing device, packaging, and so forth. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
10. In-situ monitoring of crack growth and fracture behavior in composite laminates using embedded sensors of rGO coated fabrics and GnP paper.
- Author
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Bathusha, M.S. Sikandar, Din, Israr Ud, Umer, Rehan, and Khan, Kamran A.
- Subjects
- *
LAMINATED materials , *FRACTURE mechanics , *COATED textiles , *FIBROUS composites , *COMPOSITE structures , *DETECTORS - Abstract
Graphene-based nanomaterials have found significant interest in the development of embedded sensors to monitor the fracture behavior in composite structures. In this work, in-situ crack propagation and fracture behavior within a glass fiber reinforced polymer composite (GFRP) was monitored using embedded reduced graphene oxide (rGO) coated fabrics and highly conductive graphene nanoplatelet (GnP) paper. All laminates were fabricated using the resin infusion process. The piezoresistive performance of both types of laminates was evaluated using in-plane and out-of-plane mechanical tests. The effect of GnP paper thickness (50/150/240 µm) and loading rate was also evaluated using tensile and Mode-I fracture loadings. Piezoresistivity of the sensors was reduced by increasing loading rate during tensile tests. All laminates with GnP paper exhibited poor mechanical performance under tensile loading. The laminates with 50 µm GnP paper showed highest sensitivity under Mode-I loading. In comparison to pristine laminates, the interlaminar fracture toughness of laminates with 50 µm GnP paper was reduced by 70%. Furthermore, laminates with rGO coated fabrics demonstrated stable crack propagation under Mode-I loading as compared to GnP based laminates. The fractured surfaces were analyzed using scanning electron microscopy to investigate the underlying fracture mechanisms of the sensors in the composite laminates. [Display omitted] • Composites with embedded GnP paper and rGO coated fabric sensors were manufactured. • Sensor based on thin GnP paper was found more sensitive than the thick GnP sensors. • Loading rate and thickness effects on the sensing behavior were characterized. • Increasing the load rate during in-plane tensile tests decreases the sensitivity. • rGO based sensor exhibited high mechanical properties than the GnP based sensors. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
11. A brittle material with tunable elasticity: Crêpe paper
- Author
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Nicolas Vandenberghe, Emmanuel Villermaux, Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE), and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Marketing ,[PHYS]Physics [physics] ,Materials science ,Strategy and Management ,Modulus ,Fracture mechanics ,Young's modulus ,02 engineering and technology ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,01 natural sciences ,Crêpe paper ,symbols.namesake ,[SPI]Engineering Sciences [physics] ,020303 mechanical engineering & transports ,Brittleness ,0203 mechanical engineering ,0103 physical sciences ,Tearing ,Media Technology ,symbols ,General Materials Science ,Elasticity (economics) ,Composite material ,010306 general physics ,Anisotropy - Abstract
International audience; We study the mechanical response, and tearing features of crêpe paper, a two-dimensional, very anisotropic material, with one direction much less stiff than the other one. Depending on how the soft direction has been pre-stretched or not, the apparent Young modulus of the material can be varied over a broad range, while its fracture energy remains unaltered. The classical tearing concertina problem shows that a macroscopic measurement (the shape of the teared region) provides a direct access to the fracture properties of the material (effective Young's modulus, and fracture energy). The overall discussion is conducted in the frame of Griffith's theory of fracture.
- Published
- 2019
12. Evaluation of Fracture Toughness of Paper in Wet State (I) : Effect of Fiber Furnish and Refining
- Author
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Yung Bum Seo and You Sun Roh
- Subjects
Measurement method ,Materials science ,business.product_category ,Fracture mechanics ,General Chemistry ,Work of fracture ,Paper machine ,Fracture toughness ,Media Technology ,medicine ,Dryness ,General Materials Science ,Fiber ,Composite material ,medicine.symptom ,business ,Solid content - Abstract
Fracture toughness is considered to be a good estimate of the paper breaking tendency of a paper web in a paper machine and press room. Paper breaks are caused by many factors, such as the irregular vibrations of a paper machine, impurities in the fiber furnish, and presence of shive. On a paper machine, the dryness of the paper web changes very rapidly from less than 1% to more than 95%. We tried to measure the fracture toughness of a paper web at different dryness levels in order to acquire a fundamental knowledge of paper breaks. Stretches of wet webs were also measured and compared to the changes in fracture toughness. Four different fiber furnishes were refined to different degrees, and their fracture toughness values were measured at different dryness levels (40%, 60%, 80%, and 95%). Two fracture toughness measurement methods (essential work of fracture and Tryding’s load-widening method) were compared, and found to give identical results. However, Tryding’s method was much easier to implement. The highest stretch was mostly at 80% solid content, where the highest fracture toughness occurred.
- Published
- 2016
13. New investigation of delamination using the VCCT method to predict the damage in bonded composite repair plates subjected to tensile load
- Author
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Talbi, Sofiane, Salem, Mokadem, Mechab, Belaïd, Ghomari, Tewfik, Allem, Ahmed, Bachir Bouiadjra, Belabbes, and Mehdi, Benelmaarouf
- Published
- 2024
- Full Text
- View/download PDF
14. Analysis of long crack lines in paper webs.
- Author
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Salminen, L. I., Alava, M. J., and Niskanen, K. J.
- Subjects
- *
FRACTURE mechanics , *PAPER , *SURFACE roughness , *CORROSION & anti-corrosives , *MATERIAL fatigue - Abstract
: We analyze 6500 mm long fracture lines of paper as an example of crack propagation involving disorder. The cracks are asymptotically self-affine, with a roughness exponent close to 0.6. Systematic deviations from the power-law-scaling exist below a lengthscale related to the microscopic heterogeneities and possibly to a cross-over from 3d to 2d crack propagation. Several analysis methods are discussed, including first return analysis and the detection of correlated trends. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
15. Recent advances in crack detection technologies for structures: a survey of 2022-2023 literature.
- Author
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Kaveh, Hessam, Alhajj, Reda, Shah, Pritesh, and Kulkarni, Sanjay
- Subjects
TRANSFORMER models ,FRACTURE mechanics ,INFRASTRUCTURE (Economics) ,MAINTENANCE costs ,MACHINE learning - Abstract
Introduction: Cracks, as structural defects or fractures in materials like concrete, asphalt, and metal, pose significant challenges to the stability and safety of various structures. Addressing crack detection is of paramount importance due to its implications for public safety, infrastructure integrity, maintenance costs, asset longevity, preventive maintenance, economic impact, and environmental considerations. Methods: In this survey paper, we present a comprehensive analysis of recent advancements and developments in crack detection technologies for structures, with a specific focus on articles published between 2022 and 2023. Our methodology involves an exhaustive search of the Scopus database using keywords related to crack detection and machine learning techniques. Among the 129 papers reviewed, 85 were closely aligned with our research focus. Results: We explore datasets that underpin crack detection research, categorizing them as public datasets, papers with their own datasets, and those using a hybrid approach. The prevalence and usage patterns of public datasets are presented, highlighting datasets like Crack500, Crack Forest Dataset (CFD), and Deep Crack. Furthermore, papers employing proprietary datasets and those combining public and proprietary sources are examined. The survey comprehensively investigates the algorithms and methods utilized, encompassing CNN, YOLO, UNet, ResNet, and others, elucidating their contributions to crack detection. Evaluation metrics such as accuracy, precision, recall, F1-score, and IoU are discussed in the context of assessing model performance. The results of the 85 papers are summarized, demonstrating advancements in crack detection accuracy, efficiency, and applicability. Discussion: Notably, we observe a trend towards using modern and novel algorithms, such as Vision Transformers (ViT), and a shift away from traditional methods. The conclusion encapsulates the current state of crack detection research, highlighting the integration of multiple algorithms, expert models, and innovative data collection techniques. As a future direction, the adoption of emerging algorithms like ViT is suggested. This survey paper serves as a valuable resource for researchers, practitioners, and engineers working in the field of crack detection, offering insights into the latest trends, methodologies, and challenges. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
16. The Use of Acoustic Emission Monitoring to Rank Paper Materials with Respect to Their Fracture Toughness.
- Author
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P. Gradin, D. Graham, P. Nygård, and H. Vallen
- Subjects
ACOUSTIC emission ,FRACTURE mechanics ,DEFORMATIONS (Mechanics) ,STRENGTH of materials ,USB technology ,PAPER - Abstract
Abstract  In this study, a simplified Acoustic Emission (AE) equipment, in essence an AE signal conditioner and a USB (Universal Serial Bus) data acquisition system, is used to study what happens in paper structures during mechanical loading. By the use of such equipment, some parameters that can be extracted are e.g. the stress and strain at onset of AE, the stress and strain at the onset of rapid AE defined as some numerical factor (larger then one) times the initial emission rate, the emission rate at the first stage of loading and the stress and strain at final failure i.e. when the specimen loses its load carrying ability.In this study however, the interest is focused on one particular parameter i.e. the elastic strain energy density W c at onset of AE. This is a parameter with a clear physical meaning and in this study, the correlation between this parameter and a fracture toughness measure, is investigated.The conclusion is that when nine different paper materials (with a large span regarding properties) are considered, there is a correlation (however not linear) between these two parameters. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
17. Important Factors on the Failure of Pipeline Steels with Focus on Hydrogen Induced Cracks and Improvement of Their Resistance: Review Paper
- Author
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M.A. Mohtadi-Bonab and H. Ghesmati-Kucheki
- Subjects
Materials science ,Metallurgy ,Metals and Alloys ,Fracture mechanics ,Condensed Matter Physics ,Microstructure ,Stress (mechanics) ,Cracking ,Mechanics of Materials ,Materials Chemistry ,Grain boundary ,Texture (crystalline) ,Stress corrosion cracking ,Electron backscatter diffraction - Abstract
Currently, thousands of kilometers of pipeline steels are transferring hydrocarbon fluids such as oil and natural gas in the world. Due to the fact that these pipes transport corrosive and high-pressure fluids from harsh environments, they are damaged and eventually degraded. Previous studies showed that sulphide stress cracking, hydrogen induced cracking (HIC) and stress corrosion cracking are the main destructive factors in these types of pipes. This paper focused on the HIC related failure in pipeline steel, since the role of texture and grain boundary character has not been completely recognized. Moreover, if pipeline damage is occurred by hydrogen cracks, besides the environmental pollutions, it will cost a lot to repair or replace the damaged pipeline steels. In this research, the factors influencing the initiation and propagation of the HIC cracks, such as hydrogen traps, inclusions, precipitates, microstructure and texture of steel have been investigated. Also, the existing solutions for improving the steel resistance to the HIC have been investigated based on the control of micro-alloy elements, texture and grain boundary engineering. For instance, some special dominant texture components and coincidence site lattice boundaries decrease the HIC susceptibility by providing the resistant path for crack propagation.
- Published
- 2019
18. A continuum micromechanics approach to the elasticity and strength of planar fiber networks: Theory and application to paper sheets.
- Author
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Godinho, Pedro Miguel J.S., Jajcinovic, Marina, Wagner, Leopold, Vass, Viktoria, Fischer, Wolfgang J., Bader, Thomas K., Hirn, Ulrich, Bauer, Wolfgang, Eberhardsteiner, Josef, and Hellmich, Christian
- Subjects
- *
FIBERS , *FRACTURE mechanics , *THEORY-practice relationship , *ELASTICITY - Abstract
2D materials < such > as planar fibrous networks exhibit several mechanical peculiarities, which we here decipher through a 3D-to-2D transition in the framework of continuum micromechanics or random mean-field homogenization theory. Network-to-fiber concentration (or "downscaling") tensors are derived from Eshelby–Laws matrix-inclusion problems, specified for infinitely long, infinitely flat fibers, and for infinitely flat spheroidal pores of vanishing stiffness. Overall material failure is associated with microscopic shear failure orthogonal to the fiber direction. Corresponding structure–property relations between porosity on the one hand, and in-plane stiffness as well as strength on the other hand, appear as linear. This is in good agreement with mechanical experiments carried out on pulp fibers, on pulp fiber-to-pulp fiber bonds, and on corresponding paper sheets. • A theoretical model has been developed that is able to predict the macroscopic mechanical behavior of planar transversely isotropic fiber networks out of the properties of fibers and fiber-to-fiber bonds leading to their formation. • An explicit, closed-form expression for the Hill morphology tensor of an infinitely thin oblate spheroidal inclusion embedded into a transversely isotropic, as well as an innovative numerical approach to treat associated singularities, have been used. • The model is computationally highly efficient and effective, being capable of quickly predicting the mechanical properties of virtually any planar transversely isotropic fiber network. • Theoretically predicted data for the case of wood-based paper sheets, computed from experimentally determined properties of pulp fibers and pulp fiber-to-pulp fiber bonds leading to their formation, are shown to be in good agreement with experimentally determined mechanical data for the very same paper sheets. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
19. Voronoi discretization to improve the meshless local Petrov–Galerkin method in 3D-computational fracture mechanics
- Author
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Ariannezhad, Behrooz, Shahrooi, Shahram, and Shishesaz, Mohammad
- Published
- 2023
- Full Text
- View/download PDF
20. Determination of the Mode I critical J-integral of copy paper.
- Author
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Yoshihara, Hiroshi and Yoshinobu, Masahiro
- Subjects
- *
STRAIN energy , *TENSILE tests , *TENSION loads , *STRESS intensity factors (Fracture mechanics) , *FRACTURE mechanics - Abstract
Centre-notched tension and double-edge-notched tension tests were conducted using specimens of copy paper in order to determine the Mode I critical J -integral. The crack length was varied during the test, and the effects of the test method and crack length were examined. The critical J -integral obtained from the centre-notched tension test was significantly smaller than that obtained from the double-edge-notched tension test. In both tests, the critical stress intensity factor decreased as the initial crack length increased. When the crack length correction was performed, however, the Mode I critical J -integral could be accurately obtained while reducing the aforementioned dependencies. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
21. A brittle material with tunable elasticity: Crêpe paper.
- Author
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Vandenberghe, Nicolas and Villermaux, Emmanuel
- Subjects
- *
BRITTLE material fracture , *ELASTICITY , *YOUNG'S modulus , *PROBLEM solving , *FRACTURE mechanics - Abstract
We study the mechanical response, and tearing features of crêpe paper, a two-dimensional, very anisotropic material, with one direction much less stiff than the other one. Depending on how the soft direction has been pre-stretched or not, the apparent Young modulus of the material can be varied over a broad range, while its fracture energy remains unaltered. The classical tearing concertina problem shows that a macroscopic measurement (the shape of the teared region) provides a direct access to the fracture properties of the material (effective Young's modulus, and fracture energy). The overall discussion is conducted in the frame of Griffith's theory of fracture. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
22. In-class Paper Demonstrations and Experiments for Solid Mechanics Courses.
- Author
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Xu, L. Roy
- Subjects
MECHANICS (Physics) -- Study & teaching ,CURRICULUM ,ENGINEERING students ,FRACTURE mechanics ,SCISSORS & shears - Abstract
Attending in-class paper demonstrations and performing experiments in solid mechanics courses are very effective ways for students to gain an understanding of the complicated concepts of mechanics. This paper explores a few applications of dogbone tensile tests, stress concentrations and crack kinking or mixed-mode fracture. Furthermore, this handy technique can be extended to other broader areas of mechanics education. Since only simple materials and supplies are used, copy paper, staples, scissors and a paper punching machine, students can repeat these typical mechanics experiments in future in other locations, such as in an office or at home. Therefore, this simple and effective technique can have a remarkable influence on the student's long-term career. [ABSTRACT FROM AUTHOR]
- Published
- 2008
23. Journal of Failure Analysis and Prevention Volume 22 Best Paper Award.
- Subjects
- *
FAILURE analysis , *AWARDS , *FRACTURE mechanics , *MATERIALS analysis - Published
- 2023
- Full Text
- View/download PDF
24. Analysis of localized failure in low-basis-weight paper
- Author
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R. Hägglund and Per Isaksson
- Subjects
Materials science ,business.industry ,Applied Mathematics ,Mechanical Engineering ,Isotropy ,Constitutive equation ,Non-local damage ,Fracture mechanics ,Structural engineering ,Condensed Matter Physics ,Orthotropic material ,Durability ,Tensile strength ,Low-basis-weight paper ,Fracture toughness ,Materials Science(all) ,Acoustic emission ,Mechanics of Materials ,Modelling and Simulation ,Modeling and Simulation ,Ultimate tensile strength ,General Materials Science ,business - Abstract
Continuum damage mechanics (CDM) is used to describe the post-elastic behavior of low-basis-weight paper. The relevance of undertaking studies of the mechanical behavior of low-basis-weight paper is that it enables characterization, optimization and quality control. In accordance with a CDM theory, an internal variable is introduced that represent the degree to which the material has degraded in a continuum sense and details inherent in a damage evolution law contain information about the rupture mechanism. To account for long ranging micro-structural effects, because of the fiber structure in the paper material, a non-local formulation of the constitutive law is considered. Of particular interest is the fracture toughness of the material, i.e. the ability to resist further crack propagation, as it is often a good measure of flaw tolerance and durability in the context of paper. The constitutive model discussed is verified against tensile tests on rectangular paper specimens containing pre-fabricated cracks. Acoustic emission was used to study the damage evolution in paper specimens during tensile loading. An orthotropic material description has been utilized. The model is contrasted with a purely isotropic formulation. It seems that for the type of problem analyzed in this work, an orthotropic material description does not significantly improve the predictive capability as compared to an isotropic formulation. It is concluded that the model can be used to evaluate the influence of arbitrary defect geometries, defect size and loading conditions and can easily be incorporated into a finite element code.
- Published
- 2006
25. Environmentally assisted cracking of a paper machine duplex stainless steel suction roll material
- Author
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Preet M. Singh and Jorge J. Perdomo
- Subjects
Materials science ,business.product_category ,Mechanical Engineering ,Alloy ,Metallurgy ,technology, industry, and agriculture ,Fracture mechanics ,Intergranular corrosion ,engineering.material ,Crack closure ,Cracking ,Paper machine ,Mechanics of Materials ,Corrosion fatigue ,mental disorders ,engineering ,General Materials Science ,Stress corrosion cracking ,Composite material ,Safety, Risk, Reliability and Quality ,business - Abstract
Failure analysis of a paper machine duplex stainless steel suction roll material demonstrated that the mechanism of failure was intergranular stress-corrosion cracking followed by fatigue. Crack initiation was related to both the heat treatment of the alloy and the chloride content developed in the system during paper machine shutdowns. Crack propagation occurred during normal operating conditions by a corrosion fatigue mechanism.
- Published
- 2004
26. Deformation and fracture of paper during the in-plane fracture toughness testing--Examination of the essential work of fracture method.
- Author
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Tanaka, A. and Yamauchi, T.
- Subjects
PAPER testing ,MECHANICAL loads ,FRACTURE mechanics ,DEFORMATION of surfaces ,STRENGTH of materials - Abstract
The “essential work of fracture” (EWF) method is applied to various machine-made papers. The deforming and fracturing processes of the paper samples during testing is analyzed by means of the thermographic observation. Plastic deformation zone appears in three ways when deep double edge notched tension specimens are strained under in-plane stress: i.e. 1. type (i)--appearing through whole the ligament in a vague manner and developing into a circular (or oval) zone even before or at the maximum load point; 2. type (ii)--appearing from notch tip and amalgamating into a circular (or oval) zone after the maximum load point; and 3. type (iii)--appearing from notch tip and not amalgamating into a circular (or oval) zone until the sheet failure. Specimens with small ligament length (L) are likely to belong to type (i), while those with large L to type (ii) & (iii). Among these three types, type (i) fulfills the original assumption of the EWF method best in terms of the complete ligament yielding before crack initiation. Thus the specific essential work of fracture determined using the linear relation of type (i) should be correct, although the estimated work is a little smaller than that from the linear relation of type (ii) & (iii). [ABSTRACT FROM AUTHOR]
- Published
- 2000
- Full Text
- View/download PDF
27. AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 33rd, Dallas, TX, Apr. 13-15, 1992, Technical Papers. Pt. 1 - Structures I
- Published
- 1992
28. Size Estimation of Plastic Deformation Zone at the Crack Tip of Paper under Fracture Toughness Testing
- Subjects
Papers ,Stress concentration ,Fracture mechanics ,Infrared thermography ,Fracture toughness - Abstract
Size estimation of plastic deformation zone at the crack tip of paper under fracture toughness testing was attempted not only by means of thermographic observation but also by means of the calculation based on the linear elastic fracture mechanics (LEFM). Stress concentration at the notch tips occurs at the latter stage of the testing. As developing patterns of plastic deformation zone observed by thermography changes from type(i) to type(ii) arid further to type(iii), the calculated zone size decreases. The zone calculation is useful especially in the brittle paper as a method describing the behavior of plastic deformation zone during the testing.
- Published
- 1997
29. Crease-induced targeted cutting and folding of graphene origami.
- Author
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Wei, Ning, Chen, Yang, Zhang, Yingyan, Zheng, Jin-Cheng, Zhao, Junhua, and Mai, Yiu-Wing
- Subjects
- *
ORIGAMI , *PAPER arts , *FRACTURE mechanics , *MOLECULAR dynamics , *GRAPHENE , *LASER beam cutting - Abstract
Graphene origami (G-ori) can possess unique mechanical properties and achieve some distinctive functionalization by engineering their configurations. However, it remains a tremendous challenge to modulate its formation and properties at the micro- and nano-scales. Herein, we systemically present the formation of G-ori activated by creased marks via molecular dynamics (MD) simulations. The pre-existing creased mark in graphene is created in a controlled way by transforming sp 2 to sp 3 bonds at the crease. Our results show that the presence of interlayer sp 3 bonds at the crease can direct crack growth and hence pave a new way to tailor graphene sheets into specified pieces. The crease also guides the folding process of graphene into various geometric configurations. Sophisticated G-ori can be constructed by designing rational crease distribution on the graphene surface. Checking against the folding process of paper origami shows that the crease-induced targeted folding can be achieved at both nano- and macro-scales in exactly the same way. Our findings provide a simple and feasible method to construct graphene-based nano-devices by designing rational morphological configurations of G-ori. Image 1 [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
30. Analysis of localized failure in low-basis-weight paper
- Author
-
Hägglund, R. and Isaksson, P.
- Subjects
- *
CONTINUUM damage mechanics , *CONTINUUM mechanics , *FRACTURE mechanics , *FINITE element method - Abstract
Abstract: Continuum damage mechanics (CDM) is used to describe the post-elastic behavior of low-basis-weight paper. The relevance of undertaking studies of the mechanical behavior of low-basis-weight paper is that it enables characterization, optimization and quality control. In accordance with a CDM theory, an internal variable is introduced that represent the degree to which the material has degraded in a continuum sense and details inherent in a damage evolution law contain information about the rupture mechanism. To account for long ranging micro-structural effects, because of the fiber structure in the paper material, a non-local formulation of the constitutive law is considered. Of particular interest is the fracture toughness of the material, i.e. the ability to resist further crack propagation, as it is often a good measure of flaw tolerance and durability in the context of paper. The constitutive model discussed is verified against tensile tests on rectangular paper specimens containing pre-fabricated cracks. Acoustic emission was used to study the damage evolution in paper specimens during tensile loading. An orthotropic material description has been utilized. The model is contrasted with a purely isotropic formulation. It seems that for the type of problem analyzed in this work, an orthotropic material description does not significantly improve the predictive capability as compared to an isotropic formulation. It is concluded that the model can be used to evaluate the influence of arbitrary defect geometries, defect size and loading conditions and can easily be incorporated into a finite element code. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
31. Interlayer Separation in Graphene Paper Comprising Electrochemically Exfoliated Graphene.
- Author
-
Nguyen, Dang Du, Lim, TaeGyeong, Lim, Soomook, Suk, Ji Won, and Donnet, Christophe
- Subjects
GRAPHENE ,FRACTURE mechanics ,THERMAL properties ,ENERGY storage ,CANTILEVERS - Abstract
The emergence of graphene paper comprising well-stacked graphene flakes has promoted the application of graphene-based materials in diverse fields such as energy storage devices, membrane desalination, and actuators. The fundamental properties of graphene paper such as mechanical, electrical, and thermal properties are critical to the design and fabrication of paper-based devices. In this study, the interlayer interactions in graphene paper were investigated by double cantilever beam (DCB) fracture tests. Graphene papers fabricated by flow-directed stacking of electrochemically exfoliated few-layer graphene flakes were mechanically separated into two parts, which generated force-displacement responses of the DCB sample. The analysis based on fracture mechanics revealed that the interlayer separation energy of the graphene paper was 9.83 ± 0.06 J/m
2 . The results provided a fundamental understanding of the interfacial properties of graphene papers, which will be useful for developing paper-based devices with mechanical integrity. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
32. Anisotropy in Rupture Lines of Paper Sheets
- Author
-
M. S. Couto, I. L. Menezes-Sobrinho, and I. R. B. Ribeiro
- Subjects
Hurst exponent ,Materials science ,Paper sheets ,Statistical Mechanics (cond-mat.stat-mech) ,FOS: Physical sciences ,Fracture mechanics ,Rupture lines ,Disordered Systems and Neural Networks (cond-mat.dis-nn) ,Condensed Matter - Disordered Systems and Neural Networks ,visual_art ,Newsprint ,visual_art.visual_art_medium ,Anisotropy ,Fracture process ,Composite material ,Condensed Matter - Statistical Mechanics - Abstract
We have experimentally investigated the fracture process in paper samples submitted to a uniaxial force. Five types of paper sheets (newsprint, towel, sulfite, silk and couche papers) were fractured along two orthogonal orientations. In order to characterize the rupture lines of the paper sheets we utilized the Hurst exponent. Our results indicate a dependence of the Hurst exponent on the orientation of the paper sheets for samples of newsprint and, probably, towel and silk papers. For the other types of paper the Hurst exponent does not depend on the direction of crack propagation., 6 pages, 4 figures
- Published
- 2005
33. Reply to the Comments by Marko and Fissel on the Paper "On the Deterioration of Icebergs in the Marginal Ice Zone" by Venkatesh et al. (1994).
- Subjects
ICEBERGS ,SEA ice ,ICE ,FRACTURE mechanics ,WATER temperature ,OCEAN ,OCEANOGRAPHY ,RESEARCH - Abstract
The article presents a reply by S. Venkatesh and colleagues to comments made by J. R. Marko and D. B. Fissel about their study, On the Deterioration of Icebergs in the Marginal Ice Zone. According to Venkatesh and colleagues, Marko and Fissel point to the many difficulties and expense in obtaining the necessary data to predict the deterioration of icebergs in an operational time setting. They pointed out that they are confident of the calculated deterioration rates. They said that while the calved iceberg fragments under the existing environmental conditions constitute only 2 to 3% of the original masses, the deterioration rates will increase with increasing water temperatures and sea state conditions.
- Published
- 1994
34. Creep of a fracture line in paper peeling
- Author
-
Juha Koivisto, Jari Rosti, Mikko J. Alava, Perustieteiden korkeakoulu, School of Science, Teknillisen fysiikan laitos, Department of Applied Physics, Aalto-yliopisto, and Aalto University
- Subjects
Strain energy release rate ,Materials science ,Statistical Mechanics (cond-mat.stat-mech) ,Physics ,paper ,General Physics and Astronomy ,FOS: Physical sciences ,Fracture mechanics ,Mechanics ,Disordered Systems and Neural Networks (cond-mat.dis-nn) ,Condensed Matter - Disordered Systems and Neural Networks ,Power law ,law.invention ,Physics::Geophysics ,Fracture toughness ,Acoustic emission ,Creep ,law ,Intermittency ,Fracture (geology) ,fracture lines ,Condensed Matter - Statistical Mechanics - Abstract
The slow motion of a crack line is studied via an experiment in which sheets of paper are split into two halves in a ``peel-in-nip'' (PIN) geometry under a constant load, in creep. The velocity-force relation is exponential. The dynamics of the fracture line exhibits intermittency, or avalanches, which are studied using acoustic emission. The energy statistics is a power-law, with the exponent $\beta \sim 1.8 \pm 0.1$. Both the waiting times between subsequent events and the displacement of the fracture line imply complicated stick-slip dynamics. We discuss the correspondence to tensile PIN tests and other similar experiments on in-plane fracture and the theory of creep for elastic manifolds.
- Published
- 2007
- Full Text
- View/download PDF
35. Mode I crack growth in paper exhibits three stages of strain evolution in reaching steady-state.
- Author
-
Paluskiewicz, Sarah A. and Muhlstein, Christopher L.
- Subjects
- *
METAL foils , *CORPORATE bonds , *DIGITAL image correlation - Abstract
The mechanical properties of wood fiber-based, commercial papers and metal foils are qualitatively similar, and their plane stress, Mode I crack growth resistances have not been reliably correlated with single-valued fracture mechanics parameters for centimeter-scale specimens. Experimentally-measured crack tip strain fields of Mode I cracks growing in commercial paper were used to define a three-stage, steady-state crack growth mechanism. Immediately upon loading, the net sections ahead of the cracks yielded. As the cracks began to grow, well-defined zones of (incremental) active plasticity (ZAPs) formed within the yielded ligaments. Cracks transitioned to steady-state growth with an average characteristic stress, σ c , of 20.9 MPa. In contrast to metallic foils, the characteristic stress in steady-state cracks in paper was offset by 8.3 MPa due to a 1.9 mm fiber bridging zone that scaled with the average fiber agglomerate (floc) size. The fiber network structure also induced a large, reversed steady-state zone in the crack wakes. While reversed ZAPS were previously predicted by numerical models of plane strain Mode I and III cracks under small-scale yielding conditions, they were never observed experimentally and were neglected. The types and evolution of the cumulative and incremental plastic zones in paper defined appropriate paths for steady-state J -integral calculations. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
36. Special Issue on ‘Multiaxial fatigue 2016: Experiments and modeling’: Selected papers from the 11th International Conference on Multiaxial Fatigue and Fracture (ICMFF11), held in Seville, Spain, on 1–3 June 2016
- Author
-
Thierry Palin-Luc, Sabrina Vantadori, Andrea Carpinteri, and Ali Fatemi
- Subjects
Engineering ,business.industry ,Crack propagation ,Mécanique [Sciences de l'ingénieur] ,Mechanical Engineering ,Mécanique: Mécanique des solides [Sciences de l'ingénieur] ,Fracture mechanics ,Structural engineering ,Multiaxial ,Industrial and Manufacturing Engineering ,Fracture ,Mécanique: Génie mécanique [Sciences de l'ingénieur] ,Mechanics of Materials ,Modeling and Simulation ,Crack initiation ,Fracture (geology) ,Forensic engineering ,General Materials Science ,Mécanique: Mécanique des matériaux [Sciences de l'ingénieur] ,Mécanique: Mécanique des structures [Sciences de l'ingénieur] ,business ,Fatigue - Abstract
This Special Issue of the International Journal of Fatigue contains selected papers presented at the International Conference on Multiaxial Fatigue and Fracture held in Seville, Spain, on 1–3 June 2016.
- Published
- 2017
37. Sandwich composites made of syntactic foam core and paper skin: Manufacturing and mechanical behavior.
- Author
-
Islam, Md Mainul and Kim, Ho Sung
- Subjects
COMPOSITE materials ,MECHANICAL behavior of materials ,MANUFACTURING processes ,CONSTRUCTION materials ,STARCH ,ADHESION ,FRACTURE mechanics ,SHEAR (Mechanics) - Abstract
Novel sandwich composites made of syntactic foam core and paper skin were developed as potential building materials. Interface bonding between core and skin was controlled by varying starch content. Two different microsphere size groups were employed for syntactic foam core manufacturing based on the pre-mold processing method. Properties of skin paper with starch adhesive on were found to be affected by drying time of starch adhesive. Mechanical behavior of manufactured sandwich composites in relation with properties of constituent materials was studied. Skin paper contributed to increase up to 40% in estimated flexural strength over syntactic foams, depending on starch content in adhesive between syntactic foam core and paper skin. Small microsphere size group for syntactic foam core was found to be advantageous in strengthening of sandwich composites for a given starch content in adhesive. This finding was in agreement with calculated values of estimated shear stress at interface between skin and core. Failure process of the sandwich composites was discussed in relation with load–deflection curves. Cracking of syntactic foam core was detected to be the first event in sandwich composite failure sequence. Hygroscopic behavior of syntactic foam panels was investigated. Moisture content in the foam was measured to be high for high starch content in the foam panels. No significant moisture effect on flexural strength of syntactic foam panels after being subjected to moisture about 2 months was found for both microsphere size groups. However, substantial decrease (28%) in flexural modulus was found for the foam panels made of large microspheres although not much moisture effect was found on that of small microspheres. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
38. Selected Papers from the International Symposium on Dynamic Response and Failure of Composite Materials, Draf2022.
- Author
-
Lopresto, Valentina, Papa, Ilaria, Astarita, Antonello, and Guida, Michele
- Subjects
FRACTURE mechanics ,AUXETIC materials ,SANDWICH construction (Materials) ,VISCOELASTIC materials ,IMPACT response ,COMPOSITE materials ,LAMINATED materials - Abstract
B. Palmieri et al. in "Investigation on Stress Relaxation of Discontinuous Recycled/Repurposed Carbon Fiber Composites" investigate the thermo-mechanical and viscoelastic behavior of composites made at different recycled carbon fiber (rCF) content. These are similar in structure to carbon fiber composites, where the matrix features dielectric characteristics, making the structure capable of storing electric energy. This special issue focus is dedicated to the fourth edition of the "International Symposium on Dynamic Response and Failure of Composite Materials, Draf2022" held in Ischia, Naples, from June 21-24, 2022. [Extracted from the article]
- Published
- 2023
- Full Text
- View/download PDF
39. Engineering fracture mechanics analysis of paper materials
- Author
-
Petri Mäkelä
- Subjects
Materials science ,Structural Fracture Mechanics ,Work (physics) ,Deformation theory ,Isotropy ,General Materials Science ,Forestry ,Fracture mechanics ,Mechanics ,Plasticity - Abstract
The aim of the present work was to develop an analytic fracture mechanics procedure that enables accurate predictions of failure of paper materials. Analytic expressions for prediction of the critical force and critical elongation of edge-notched paper webs were developed based on isotropic deformation theory of plasticity and J-integral theory. The analytic expressions were applied to predict the critical force and elongation of paper webs with different edge-notch sizes for six different paper materials. The accuracy of the analytic failure predictions was verified by numerical predictions and experiments on edge-notched paper webs, showing that the developed engineering fracture mechanics analysis procedure predicted failure accurately.
- Published
- 2012
40. Numerical integration in G/XFEM analysis of 2-D fracture mechanics problems for physically nonlinear material and cohesive crack propagation
- Author
-
Campos, Bruna Caroline, Barros, Felicio Bruzzi, and Penna, Samuel Silva
- Published
- 2022
- Full Text
- View/download PDF
41. An Efficient Mixed-Mode Brittle Fracture Experiment Using Paper
- Author
-
Mark Flores and L. Roy Xu
- Subjects
Materials science ,business.industry ,Computational Mechanics ,Fracture mechanics ,Structural engineering ,Mixed mode ,Fracture toughness ,Machining ,Mechanics of Materials ,Modeling and Simulation ,Fracture (geology) ,Mixed mode fracture ,Composite material ,business ,Brittle fracture - Abstract
Mixed-mode fracture is a common failure phenomenon of materials, while its experiment requires at least a material test machine, test materials and special machining procedures. In this paper, a simple but effective mixed-mode fracture experiment using office paper is proposed, so one can easily conduct the mixed-mode fracture experiment and understand its fracture criteria such as the maximum tensile stress (MTS) criterion.
- Published
- 2013
42. Failure Stress in Notched Paper Sheets
- Author
-
Vicente Flores Lara, Carlos A. Mora Santos, Jorge Bedolla Hernández, Maribel Mendoza Nuñez, and Orlando Susarrey Huerta
- Subjects
Materials science ,business.industry ,Mechanical Engineering ,Crack tip opening displacement ,Fracture mechanics ,Structural engineering ,Crack growth resistance curve ,Tortuosity ,Stress (mechanics) ,Crack closure ,Mechanics of Materials ,mental disorders ,General Materials Science ,Composite material ,business ,Compact tension specimen ,Stress concentration - Abstract
In this work the crack initiation stress of notched specimens of filter paper is studied. The paper in the microstructure has a random array in their fibers while macroscopically it behaves anisotropically. The self-affine crack mechanics is used to study the size effect in the tensile behavior of this kind of paper under the presence of several conditions of geometrical notches. While in the traditional fracture mechanics the crack initiation stress is a material parameter when is reached a critical level at the crack tip, in the self-affine crack mechanics, depends moreover of the resulting tortuosity of the crack. Four geometrical arrangements in two sizes we considered: centered circular notch, centered lineal notch, sided circular notches and without notch at 10 and 300 mm width with a relation 2a/w = 0.25 under the same loading conditions. In this, the without notch specimens present the higher stress, all other notched specimens presented a similar crack initiation stress about 1 % of difference among them, and the crack growth is not affected by the geometry of notch. In spite of this difference, no one of the specimens reach the theoretical stress concentration of 3 such as predicted the classical stress theory.
- Published
- 2013
43. Paper multilayer with a fracture toughness of steel
- Author
-
J. Zechner and Otmar Kolednik
- Subjects
Toughness ,Materials science ,Mechanical Engineering ,Transferability ,Fracture mechanics ,Crack growth resistance curve ,Lightning arrester ,Fracture toughness ,Mechanics of Materials ,mental disorders ,Solid mechanics ,General Materials Science ,Composite material ,Compact tension specimen - Abstract
We demonstrate in this paper that commercially available printing paper can reach very high fracture toughness, comparable to that of steel, simply due to a special arrangement of the paper sheets with respect to the crack. Fracture mechanics experiments are conducted on single sheets of paper as well as on multilayer specimens in crack divider and crack arrester configuration. It is demonstrated that an arrangement in crack arrester configuration leads to an increase of the fracture toughness by a factor ten. An explanation of the effect is given and the transferability to other materials is discussed.
- Published
- 2013
44. Size Estimation of Plastic Deformation Zone at the Crack Tip of Paper under Fracture Toughness Testing
- Author
-
Tanaka, Atsushi and Yamauchi, Tatsuo
- Subjects
Papers ,Stress concentration ,Fracture mechanics ,Infrared thermography ,Fracture toughness - Abstract
Size estimation of plastic deformation zone at the crack tip of paper under fracture toughness testing was attempted not only by means of thermographic observation but also by means of the calculation based on the linear elastic fracture mechanics (LEFM). Stress concentration at the notch tips occurs at the latter stage of the testing. As developing patterns of plastic deformation zone observed by thermography changes from type(i) to type(ii) arid further to type(iii), the calculated zone size decreases. The zone calculation is useful especially in the brittle paper as a method describing the behavior of plastic deformation zone during the testing.
- Published
- 1997
45. Tensile and tearing fracture properties of graphene oxide papers intercalated with carbon nanotubes.
- Author
-
Nizam Uddin, Md., Zhen-Dong Huang, Yiu-Wing Mai, and Jang-Kyo Kim
- Subjects
- *
TENSILE strength , *FRACTURE mechanics , *MULTIWALLED carbon nanotubes , *GRAPHENE oxide , *BRITTLE fractures , *OSCILLATIONS - Abstract
The fracture behaviors of graphene oxide (GO) and GO/multi-walled carbon nanotube (MWCNT) hybrid papers are studied in both quasi-static mode-I opening and mode-III tearing fracture. Large GO papers give rise to a higher energy release rate and tearing toughness than those made from small GO sheets: about 36% and 70% enhancements are shown for the large GO papers due to a more compact structure and better GO sheet alignment. Hybridization of GO papers with MWCNTs also improves these properties when up to 5 wt.% of MWCNTs is incorporated, attributed to the stronger GO interlayer bonds through π-π interactions with intercalated MWCNTs. Fracture surface examination indicates that cleavage failure prevails in mode-I fracture depending on the size of GO sheets: the unsorted and large GO papers fail mainly by brittle cleavage of GO sheets whereas small GO papers fail by combined brittle cleavage and minor pullout following debonding of GO bundles. In contrast, combination of cleavage and debonding failures is dominant in mode-III fracture of GO papers, regardless of GO size. The torn edges present typical characteristics of a saw-tooth wave with disordered oscillation where the large GO papers exhibit generally higher amplitude peaks than the small GO papers. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
46. Failure Analysis of PHILOS Plate Construct Used for Pantalar Arthrodesis Paper I—Analysis of the Plate
- Author
-
Farah Hamandi, Madhurima Vallentyne, Richard T. Laughlin, Jason Ina, Michael A. Boin, Tarun Goswami, and Kathleen Shugart
- Subjects
lcsh:TN1-997 ,arthrodesis ,030222 orthopedics ,corrosion ,Materials science ,Shear force ,Metals and Alloys ,Fracture mechanics ,pantalar ,030206 dentistry ,failure modes ,03 medical and health sciences ,0302 clinical medicine ,Corrosion fatigue ,Ultimate tensile strength ,Fracture (geology) ,Pitting corrosion ,fracture surface ,scratching ,General Materials Science ,Displacement (orthopedic surgery) ,Composite material ,Failure mode and effects analysis ,lcsh:Mining engineering. Metallurgy - Abstract
The failure of a proximal humerus internal locking system (PHILOS) used in a pantalar arthrodesis was investigated in this paper. PHILOS constructs are hybrids using locking and non-locking screws. Both the plate and the screws used in the fusion were obtained for analysis. However, only the plate failure analysis is reported in this paper. The implant had failed in several pieces. Optical and scanning electron microscopic analyses were performed to characterize the failure mode(s) and fracture surface. The chemical composition and mechanical properties of the plate were determined and compared to controlling specifications to manufacture the devices. We found that equivalent tensile strength exceeded at the locations of high stress, axial, and angular displacement and matched the specification at the regions of lower stress/displacement. Such a region-wise change in mechanical properties with in vivo utilization has not been reported in the literature. Evidence of inclusions was qualitatively determined for the stainless steel 316L plate failing the specifications. Pitting corrosion, scratches, discoloration and debris were present on the plate. Fracture surface showed (1) multi-site corrosion damage within the screw holes forming a 45° maximum shear force line for crack-linking, and (2) crack propagation perpendicular to the crack forming origin that may have formed due to the presence of inclusions. Fracture features such as beach marks and striations indicating that corrosion may have initiated the crack(s), which grew by fatigue over a period of time. In conclusion, the most likely mechanism of failure for the device was due to corrosion fatigue and lack of bony in-growth on the screws that may have caused loosening of the device causing deformity and pre-mature failure.
- Published
- 2018
47. THE RELATIONSHIP BETWEEN DP, FRACTURE DEGREE AND MECHANICAL STRENGTH OF CELLULOSE Iβ IN INSULATION PAPER BY MOLECULAR DYNAMIC SIMULATIONS.
- Author
-
WANG, YOU-YUAN, YANG, TAO, TIAN, MIAO, and LIAO, RUI-JIN
- Subjects
- *
DEGREE of polymerization , *FRACTURE mechanics , *CELLULOSE , *MOLECULAR dynamics , *TRANSFORMER insulation , *YOUNG'S modulus , *HYDROGEN bonding - Abstract
The degree of polymerization (DP) has been regarded as an important symbol of mechanical strength, reflecting the aging condition of transformer insulation paper. In this article, a new concept called fracture degree is proposed on the basis of DP. First, nine cellulose Iβ crystal models with different fracture degrees were built. Then relevant mechanical parameters and hydrogen bond numbers were calculated by molecular dynamics (MD) simulation. Results showed that during the aging process of insulation paper with fracture of cellulose chain, the elastic constant C33 produces appreciable impact on the Young's modulus (E). With the decrease of DP and increase of fracture degree, the Young's modulus step decreases. To the 50% and 100% fracture degree models respectively, the relationship between their different degrees of polymerization and Young's modulus is subjected to similar exponential distributions. With the increase of the fracture degree, the average hydrogen bond number drops, and the change rules apply to the Young's modulus. Since hydrogen bond is the main factor of mechanical strength, it can be inferred that the fracture degree influences mechanical strength seriously. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
48. Validation of isotropic deformation theory of plasticity for fracture mechanics analysis of paper materials
- Author
-
Håkon Ottar Nordhagen, Petri Mäkelä, and Øyvind Weiby Gregersen
- Subjects
Work (thermodynamics) ,Materials science ,business.industry ,Transferability ,Isotropy ,Deformation theory ,Forestry ,Fracture mechanics ,Materials testing ,Structural engineering ,Plasticity ,Fracture (geology) ,General Materials Science ,Composite material ,business - Abstract
The aim of this work was to validate that isotropic deformation theory of plasticity is a suitable material modelling level for fracture mechanics analysis of paper materials, as has been indicated ...
- Published
- 2009
49. The physics of paper
- Author
-
Mikko J. Alava and Kaarlo Niskanen
- Subjects
Physics ,Paperboard ,Brittleness ,Creep ,Rheology ,visual_art ,visual_art.visual_art_medium ,General Physics and Astronomy ,Mechanical engineering ,Polymer physics ,Fracture mechanics ,Statistical mechanics ,Viscoelasticity - Abstract
Paper is a material known to everybody. It has a network structure consisting of wood fibres that can be mimicked by cooking a portion of spaghetti and pouring it on a plate, to form a planar assembly of fibres that lie roughly horizontal. Real paper also contains other constituents added for technical purposes.This review has two main lines of thought. First, in the introductory part, we consider the physics that one encounters when 'using' paper, an everyday material that exhibits the presence of disorder. Questions arise, for instance, as to why some papers are opaque and others translucent, some are sturdy and others sloppy, some readily absorb drops of liquid while others resist the penetration of water. The mechanical and rheological properties of paper and paperboard are also interesting. They are inherently dependent on moisture content. In humid conditions paper is ductile and soft, in dry conditions brittle and hard.In the second part we explain in more detail research problems concerned with paper. We start with paper structure. Paper is made by dewatering a suspension of fibres starting from very low content of solids. The processes of aggregation, sedimentation and clustering are familiar from statistical mechanics. Statistical growth models or packing models can simulate paper formation well and teach a lot about its structure.The second research area that we consider is the elastic and viscoelastic properties and fracture of paper and paperboard. This has traditionally been the strongest area of paper physics. There are many similarities to, but also important differences from, composite materials. Paper has proved to be convenient test material for new theories in statistical fracture mechanics. Polymer physics and memory effects are encountered when studying creep and stress relaxation in paper. Water is a 'softener' of paper. In humid conditions, the creep rate of paper is much higher than in dry conditions.The third among our topics is the interaction of paper with water. The penetration of water into paper is an interesting transport problem because wood fibres are hygroscopic and swell with water intake. The porous fibre network medium changes as the water first penetrates into the pore space between the fibres and then into the fibres. This is an area where relatively little systematic research has been done. Finally, we summarize our thoughts on paper physics.
- Published
- 2006
50. 2013 Koiter Medal Paper: Crack-Tip Fields and Toughness of Two-Dimensional Elastoplastic Lattices.
- Author
-
Tankasala, H. C., Deshpande, V. S., and Fleck, N. A.
- Subjects
- *
ELASTOPLASTICITY , *TWO-dimensional materials (Nanotechnology) , *FRACTURE toughness , *CRYSTAL lattices , *FRACTURE mechanics - Abstract
The dependence of the fracture toughness of two-dimensional (2D) elastoplastic lattices upon relative density and ductility of cell wall material is obtained for four topologies: the triangular lattice, kagome lattice, diamond lattice, and the hexagonal lattice. Crack-tip fields are explored, including the plastic zone size and crack opening displacement. The cell walls are treated as beams, with a material response given by the Ramberg-Osgood law. There is choice in the criterion for crack advance, and two extremes are considered: (i) the maximum local tensile strain (LTS) anywhere in the lattice attains the failure strain or (ii) the average tensile strain (ATS) across the cell wall attains the failure strain (which can be identified with the necking strain). The dependence of macroscopic fracture toughness upon failure strain, strain hardening exponent, and relative density is obtained for each lattice, and scaling laws are derived. The role of imperfections in degrading the fracture toughness is assessed by random movement of the nodes. The paper provides a strategy for obtaining lattices of high toughness at low density, thereby filling gaps in material property space. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
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