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Understanding the strength degradation of glass and carbon fibers due to exposure to liquids over time is important for structural applications. A model has been developed for glass fibers that links the strength reduction in water to the increase of the Griffith flaw size of the fibers. The speed of the increase is determined by regular chemical dissolution kinetics of glass in water. Crack growth and strength reduction can be predicted for several water temperatures and pH, based on the corresponding dissolution constants. Agreement with experimental results for the case of water at 60 °C with a pH of 5.8 is reasonably good. Carbon fibers in water and toluene and glass fibers in toluene do not chemically react with the liquid. Subsequently no strength degradation is expected and will be confirmed experimentally. All fiber strength measurements are carried out on bundles. The glass fibers are R-glass.
Andreas T. Echtermeyer; Andrey E. Krauklis; Abedin I. Gagani; Erik Sæter. Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics. Fibers 2019, 7, 107 .
AMA StyleAndreas T. Echtermeyer, Andrey E. Krauklis, Abedin I. Gagani, Erik Sæter. Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics. Fibers. 2019; 7 (12):107.
Chicago/Turabian StyleAndreas T. Echtermeyer; Andrey E. Krauklis; Abedin I. Gagani; Erik Sæter. 2019. "Zero Stress Aging of Glass and Carbon Fibers in Water and Oil—Strength Reduction Explained by Dissolution Kinetics." Fibers 7, no. 12: 107.
Long-term creep properties and the effect of water are important for fiber reinforced polymer (FRP) composite materials used in offshore applications. Epoxies are often used as a matrix material in such composites. A typical design lifetime of offshore FRP structures is 25 or more years in direct contact with water leading to some deterioration of the material properties. Knowing and predicting the extent of the material property deterioration in water is of great interest for designers and users of the offshore FRP structures. It has been established that the time–temperature superposition principle (TTSP) is a useful tool for estimating changes in properties of polymer materials at long times or extreme temperatures. In this work, a time–temperature–plasticization superposition principle (TTPSP) is described and used for predicting the long-term creep behavior of an epoxy compound. The studied epoxy does not degrade chemically via hydrolysis or chain scission but is negatively affected by plasticization with water. The methodology enables prediction of the long-term viscoelastic behavior of amorphous polymers at temperatures below the glass transition (Tg) using short-term creep experimental data. The results also indicate that it is possible to estimate the creep behavior of the plasticized polymer based on the short-term creep data of the respective dry material and the difference between Tg values of dry polymer and plasticized polymer. The methodology is useful for accelerated testing and for predicting the time-dependent mechanical properties of a plasticized polymer below the glass transition temperature.
Andrey E. Krauklis; Anton G. Akulichev; Abedin Gagani; Andreas T. Echtermeyer. Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy. Polymers 2019, 11, 1848 .
AMA StyleAndrey E. Krauklis, Anton G. Akulichev, Abedin Gagani, Andreas T. Echtermeyer. Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy. Polymers. 2019; 11 (11):1848.
Chicago/Turabian StyleAndrey E. Krauklis; Anton G. Akulichev; Abedin Gagani; Andreas T. Echtermeyer. 2019. "Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy." Polymers 11, no. 11: 1848.
Glass fiber-reinforced composites are exposed to hydrolytic degradation in subsea and offshore applications. Fiber-matrix interphase degradation was observed after the matrix was fully saturated with water and typical water absorption tests according to ASTM D5229 were stopped. Due to water-induced dissolution, fiber-matrix interphase flaws were formed, which then lead to increased water uptake. Cutting sample plates from a larger laminate, where the fibers were running parallel to the 1.5 mm long short edge, allowed the hydrolytic degradation process to be studied. The analysis is based on a full mechanistic mass balance approach considering all the composite’s constituents: water uptake and leaching of the matrix, dissolution of the glass fibers, and dissolution of the composite interphase. These processes were modeled using a combination of Fickian diffusion and zero-order kinetics. For the composite laminate studied here with a saturated epoxy matrix, the fiber matrix interphase is predicted to be fully degraded after 22 to 30 years.
Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase. Coatings 2019, 9, 263 .
AMA StyleAndrey E. Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase. Coatings. 2019; 9 (4):263.
Chicago/Turabian StyleAndrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2019. "Long-Term Hydrolytic Degradation of the Sizing-Rich Composite Interphase." Coatings 9, no. 4: 263.
Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to water and humid environments for decades, with a typical design lifetime being around 25 years or more. During this lifetime, these materials are affected by various temperatures, acidity levels, and mechanical loads. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was able to explain the long-term dissolution of R-glass fibres, considering the influence of the pH, temperature, and stress corrosion. The effects of these environmental conditions on the dissolution rate constants and activation energies of dissolution were obtained. Experimentally, dissolution was measured using High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). For stress corrosion, a custom rig was designed and used. The temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. In comparison with neutral conditions, basic and acidic aqueous environments showed an increase in the dissolution rates, affecting the lifetime of glass fibres negatively. External loads also increased glass dissolution rates due to stress corrosion. The model was able to capture all of these effects.
Andrey E. Krauklis; Abedin I. Gagani; Kristine Vegere; Ilze Kalnina; Maris Klavins; Andreas T. Echtermeyer. Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion. Fibers 2019, 7, 22 .
AMA StyleAndrey E. Krauklis, Abedin I. Gagani, Kristine Vegere, Ilze Kalnina, Maris Klavins, Andreas T. Echtermeyer. Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion. Fibers. 2019; 7 (3):22.
Chicago/Turabian StyleAndrey E. Krauklis; Abedin I. Gagani; Kristine Vegere; Ilze Kalnina; Maris Klavins; Andreas T. Echtermeyer. 2019. "Dissolution Kinetics of R-Glass Fibres: Influence of Water Acidity, Temperature, and Stress Corrosion." Fibers 7, no. 3: 22.
Swelling in fiber-reinforced composites is anisotropic. In this work, dealing with glass fiber epoxy composite immersed in distilled water, swelling coefficients are obtained in each direction experimentally. Swelling behaviour in the fiber direction was constrained by the non-swelling fibers and was close to null, while swelling in the transverse directions was found to occur freely—similar to the unconstrained polymer. An analytical method for predicting anisotropic swelling in composites from the swelling of the matrix polymer is reported in this work. The method has an advantage that it is simple to use in practice and requires only a swelling coefficient of the matrix polymer, elastic constants of the matrix and fibers, and a known fiber volume fraction of the composite. The method was validated using finite element analysis. Good agreement was obtained and is reported between experimental hygroscopic swelling data, analytical and numerical results for composite laminates, indicating the validity of this predictive approach.
Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer. Journal of Composites Science 2019, 3, 10 .
AMA StyleAndrey E. Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer. Journal of Composites Science. 2019; 3 (1):10.
Chicago/Turabian StyleAndrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2019. "Prediction of Orthotropic Hygroscopic Swelling of Fiber-Reinforced Composites from Isotropic Swelling of Matrix Polymer." Journal of Composites Science 3, no. 1: 10.
Producing precision parts requires good control of the production parameters. When casting thermoset polymers an understanding of the curing process, with its heat release and associated temperature changes, is important. This paper describes how the cure of a polymer of unknown detailed chemical composition in a large part can be predicted and how the necessary material properties required for the predictions can be obtained. The approach given is a relatively simple method that a part manufacturer can perform. It will not characterize chemical reactions in detail, but it gives sufficient accuracy to describe the process. The procedures will be explained for an example of casting a large block of a filled two-component thermoset polyurethane. The prediction of the degree of cure, the associated heat and temperature increase during the curing of a polymer was successfully done using a standard finite element program with the input parameters reaction energy, the Arrhenius pre-factor and the kinetic function, which describes the chemical reaction. The three parameters could be obtained with standard Differential Scanning Calorimetry (DSC) equipment. The data were analyzed with the model-free isoconversional method combined with the compensation effect. The same set of parameters allowed the prediction of experimental cure behavior over two orders of magnitude of time and at a curing temperature range from room temperature up to 420 K.
Søren Heinze; Andreas T. Echtermeyer. A Practical Approach for Data Gathering for Polymer Cure Simulations. Applied Sciences 2018, 8, 2227 .
AMA StyleSøren Heinze, Andreas T. Echtermeyer. A Practical Approach for Data Gathering for Polymer Cure Simulations. Applied Sciences. 2018; 8 (11):2227.
Chicago/Turabian StyleSøren Heinze; Andreas T. Echtermeyer. 2018. "A Practical Approach for Data Gathering for Polymer Cure Simulations." Applied Sciences 8, no. 11: 2227.
Epoxies are often exposed to water due to rain and humid air environments. Epoxy yellows during its service time under these conditions, even when protected from UV radiation. The material’s color is not regained upon redrying, indicating irreversible aging mechanisms. Understanding what causes a discoloration is of importance for applications where the visual aspect of the material is significant. In this work, irreversible aging mechanisms and the cause of yellowing were identified. Experiments were performed using a combination of FT-NIR, ATR-FT-IR, EDX, HR-ICP-MS, pH measurements, optical microscopy, SEM, and DMTA. Such extensive material characterization and structured logic of investigation, provided the necessary evidence to investigate the long-term changes. No chain scission (hydrolysis or oxidation-induced) was present in the studied common DGEBA/HDDGE/IPDA/POPA epoxy, whilst it was found that thermo-oxidation and leaching occurred. Thermo-oxidation involved evolution of carbonyl groups in the polymeric carbon–carbon backbone, via nucleophilic radical attack and minor crosslinking of the HDDGE segments. Four probable reactive sites were identified, and respective reactions were proposed. Compounds involved in leaching were identified to be epichlorohydrin and inorganic impurities but were found to be unrelated to yellowing. Carbonyl formation in the epoxy backbone due to thermo-oxidation was the cause for the yellowing of the material.
Andrey E. Krauklis; Andreas T. Echtermeyer. Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy. Polymers 2018, 10, 1017 .
AMA StyleAndrey E. Krauklis, Andreas T. Echtermeyer. Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy. Polymers. 2018; 10 (9):1017.
Chicago/Turabian StyleAndrey E. Krauklis; Andreas T. Echtermeyer. 2018. "Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy." Polymers 10, no. 9: 1017.
Due to the increasing ease of use and the superiority of the results, distributed strain measurements, utilizing Optical Backscatter Reflectometry (OBR), have become more important and widespread over the last few years. Strains are calculated from the difference between an actual optical Raleigh backscattering measurement and an initial reference value. However, under certain physical conditions, e.g., pinching or microbending of the optical fiber, no meaningful strain values are yielded by the commonly-used method to analyze OBR data. Such conditions were experienced in this study where the optical fiber was embedded into hardening epoxy for measuring shrinkage due to curing. In this work, it is shown that a new data analysis method called the “running reference analysis method” can overcome such obstacles and deliver meaningful strain values in circumstances in which the traditional method fails. In the new approach, each measurement is compared to the previous measurement, and the strain differences are added up to the absolute strain value. This method does not require a new experimental technique and will also work on old measurement files. It is also useful for other types of (OBR) strain measurements that contain many outliers and is not restricted to the investigation of cured epoxy.
Søren Heinze; Andreas T. Echtermeyer. A Running Reference Analysis Method to Greatly Improve Optical Backscatter Reflectometry Strain Data from the Inside of Hardening and Shrinking Materials. Applied Sciences 2018, 8, 1137 .
AMA StyleSøren Heinze, Andreas T. Echtermeyer. A Running Reference Analysis Method to Greatly Improve Optical Backscatter Reflectometry Strain Data from the Inside of Hardening and Shrinking Materials. Applied Sciences. 2018; 8 (7):1137.
Chicago/Turabian StyleSøren Heinze; Andreas T. Echtermeyer. 2018. "A Running Reference Analysis Method to Greatly Improve Optical Backscatter Reflectometry Strain Data from the Inside of Hardening and Shrinking Materials." Applied Sciences 8, no. 7: 1137.
Some large engineering structures are made by casting polymers into a mold. The structures can have complicated geometries and may be filled with other components, such as electrical transformers. This study investigated casting of large components made of epoxy. Epoxy is easy to pour, bonds well and has relatively low cure shrinkage. However, the cure shrinkage can lead to significant stresses or strains, causing large deformations that can lead to cracks.Understanding the curing process and related shrinkage is important for designing molds and controlling the production process. This study applied a new experimental method to measure strains due to cure shrinkage allowing many accurate local measurements along the length of an optical measurement fiber. The method is based on Optical Backscatter Reflectometry. Six distinct stages of the curing process can be identified. Previous measurements were limited to a few point measurements in small samples. This paper shows cure shrinkage in large samples and identifies some unexpected changes in behavior when going from small to large specimens. The behavior is explained qualitatively.
Søren Heinze; Andreas T. Echtermeyer. In-Situ Strain Measurements in Large Volumes of Hardening Epoxy Using Optical Backscatter Reflectometry. Applied Sciences 2018, 8, 1141 .
AMA StyleSøren Heinze, Andreas T. Echtermeyer. In-Situ Strain Measurements in Large Volumes of Hardening Epoxy Using Optical Backscatter Reflectometry. Applied Sciences. 2018; 8 (7):1141.
Chicago/Turabian StyleSøren Heinze; Andreas T. Echtermeyer. 2018. "In-Situ Strain Measurements in Large Volumes of Hardening Epoxy Using Optical Backscatter Reflectometry." Applied Sciences 8, no. 7: 1141.
There is a growing interest in replacing steel tubes that operate in high pressure and high temperature environments with composite tubes. Such applications can include drilling risers and drill strings for the offshore oil industry. Replacing steel with composites in such applications will greatly reduce the weight of the equipment and require less buoyancy elements built into the structures. This paper seeks to investigate how composite tubes behave when submerged and how optical fibers can be used as a health monitoring system for such applications utilizing Rayleigh optical backscatter reflectometry. A glass fiber filament wound tube of 100 mm inner diameter and 600 mm length with a layup of approximately [89°, ±12.7°, ±45°] was exposed to external hydrostatic pressure in an autoclave. Optical fibers glued to the outer surface of the tube were used to measure strain during testing. A strain field reading was carried out every 0.5 bar pressure increase and correlated well with strain fields from a finite element analysis of the tube. The finite element analysis predicted buckling at 4.33 bar, assuming no material failure; however, the tube buckled at 3.5 bar due to a sudden stiffness reduction from material failure. The optical fibers could detect the early failure and functioned well as a health monitoring system.
Eivind Hugaas; Nils Petter Vedvik; Andreas T. Echtermeyer. Buckling due to external pressure of a composite tube measured by Rayleigh optical backscatter reflectometry and analyzed by finite elements. Structural Control and Health Monitoring 2018, 25, e2205 .
AMA StyleEivind Hugaas, Nils Petter Vedvik, Andreas T. Echtermeyer. Buckling due to external pressure of a composite tube measured by Rayleigh optical backscatter reflectometry and analyzed by finite elements. Structural Control and Health Monitoring. 2018; 25 (8):e2205.
Chicago/Turabian StyleEivind Hugaas; Nils Petter Vedvik; Andreas T. Echtermeyer. 2018. "Buckling due to external pressure of a composite tube measured by Rayleigh optical backscatter reflectometry and analyzed by finite elements." Structural Control and Health Monitoring 25, no. 8: e2205.
Monitoring water content and predicting the water-induced drop in strength of fiber-reinforced composites are of great importance for the oil and gas and marine industries. Fourier transform infrared (FTIR) spectroscopic methods are broadly available and often used for process and quality control in industrial applications. A benefit of using such spectroscopic methods over the conventional gravimetric analysis is the possibility to deduce the mass of an absolutely dry material and subsequently the true water content, which is an important indicator of water content-dependent properties. The objective of this study is to develop an efficient and detailed method for estimating the water content in epoxy resins and fiber-reinforced composites. In this study, Fourier transform near-infrared (FT-NIR) spectroscopy was applied to measure the water content of amine-epoxy neat resin. The method was developed and successfully extended to glass fiber-reinforced composite materials. Based on extensive measurements of neat resin and composite samples of varying water content and thickness, regression was performed, and the quantitative absorbance dependence on water content in the material was established. The mass of an absolutely dry resin was identified, and the true water content was obtained. The method was related to the Beer–Lambert law and explained in such terms. A detailed spectroscopic method for measuring water content in resins and fiber-reinforced composites was developed and described.
Andrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites. Materials 2018, 11, 586 .
AMA StyleAndrey E. Krauklis, Abedin I. Gagani, Andreas T. Echtermeyer. Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites. Materials. 2018; 11 (4):586.
Chicago/Turabian StyleAndrey E. Krauklis; Abedin I. Gagani; Andreas T. Echtermeyer. 2018. "Near-Infrared Spectroscopic Method for Monitoring Water Content in Epoxy Resins and Fiber-Reinforced Composites." Materials 11, no. 4: 586.
Two different series of biobased polyethylene (BioPE) were used for the manufacturing of biocomposites, complemented with thermomechanical pulp (TMP) fibers. The intrinsic hydrophilic character of the TMP fibers was previously modified by grafting hydrophobic compounds (octyl gallate and lauryl gallate) by means of an enzymatic-assisted treatment. BioPE with low melt flow index (MFI) yielded filaments with low void fraction and relatively low thickness variation. The water absorption of the biocomposites was remarkably improved when the enzymatically-hydrophobized TMP fibers were used. Importantly, the 3D printing of BioPE was improved by adding 10% and 20% TMP fibers to the composition. Thus, 3D printable biocomposites with low water uptake can be manufactured by using fully biobased materials and environmentally-friendly processes.
Daniel Filgueira; Solveig Holmen; Johnny K. Melbø; Diego Moldes; Andreas T. Echtermeyer; Gary Chinga-Carrasco. 3D Printable Filaments Made of Biobased Polyethylene Biocomposites. Polymers 2018, 10, 314 .
AMA StyleDaniel Filgueira, Solveig Holmen, Johnny K. Melbø, Diego Moldes, Andreas T. Echtermeyer, Gary Chinga-Carrasco. 3D Printable Filaments Made of Biobased Polyethylene Biocomposites. Polymers. 2018; 10 (3):314.
Chicago/Turabian StyleDaniel Filgueira; Solveig Holmen; Johnny K. Melbø; Diego Moldes; Andreas T. Echtermeyer; Gary Chinga-Carrasco. 2018. "3D Printable Filaments Made of Biobased Polyethylene Biocomposites." Polymers 10, no. 3: 314.
Fluid diffusion in fiber reinforced composites is typically anisotropic. Diffusivity in the fiber direction is faster than in the transverse direction. The reason for this behavior is not yet fully understood. In this work, dealing with glass fiber epoxy composite immersed in distilled water, an experimental procedure for determination of anisotropic diffusion constants from a laminate is presented. The method has the advantage that it does not require sealing of the samples edges because 3-D anisotropic diffusion theory is implemented for obtaining the diffusion constants. A microscale model is presented, where matrix and fiber bundles are modeled separately. The matrix properties have been obtained experimentally and the fiber bundle properties have been deduced by the composite homogenized diffusivity model. The analysis indicates that the anisotropic diffusion of the composite is due to inherent anisotropic properties of the fiber bundles.
Abedin Gagani; Yiming Fan; Anastasia H Muliana; Andreas T Echtermeyer. Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites. Journal of Composite Materials 2017, 52, 2321 -2335.
AMA StyleAbedin Gagani, Yiming Fan, Anastasia H Muliana, Andreas T Echtermeyer. Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites. Journal of Composite Materials. 2017; 52 (17):2321-2335.
Chicago/Turabian StyleAbedin Gagani; Yiming Fan; Anastasia H Muliana; Andreas T Echtermeyer. 2017. "Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites." Journal of Composite Materials 52, no. 17: 2321-2335.
Fibre-reinforced plastics are praised for their good corrosion resistance. However, when this resistance needs to be documented for safety-critical applications extensive and time-consuming test programmes are needed. A better quantitative understanding of the fundamental mechanisms behind degradation should help to reduce the testing effort. A multiscale approach for modelling degradation in water and hydrocarbons is described. The environmental degradation happens on the scale of the constituent materials: fibres, matrix and sizing (interface). Local concentration profiles of the fluid inside the material need to be known to predict degradation. The global engineering properties are then calculated from the constituents using finite element analysis and homogenisation. Describing degradation with the multiscale approach is a promising method for reducing the current test effort. Much more work is needed to create enough confidence in the models that then can be used for designing real components. The first steps are described here showing the models and how they can be connected.
Andreas T. Echtermeyer; Abedin Gagani; Andrejs Krauklis; Tobiasz Mazan. Multiscale Modelling of Environmental Degradation—First Steps. Internal Variables in Thermoelasticity 2017, 244, 135 -149.
AMA StyleAndreas T. Echtermeyer, Abedin Gagani, Andrejs Krauklis, Tobiasz Mazan. Multiscale Modelling of Environmental Degradation—First Steps. Internal Variables in Thermoelasticity. 2017; 244 ():135-149.
Chicago/Turabian StyleAndreas T. Echtermeyer; Abedin Gagani; Andrejs Krauklis; Tobiasz Mazan. 2017. "Multiscale Modelling of Environmental Degradation—First Steps." Internal Variables in Thermoelasticity 244, no. : 135-149.
Jon Harald L. Grave; Magnus L. Håheim; Andreas T. Echtermeyer. Measuring changing strain fields in composites with Distributed Fiber-Optic Sensing using the optical backscatter reflectometer. Composites Part B: Engineering 2015, 74, 138 -146.
AMA StyleJon Harald L. Grave, Magnus L. Håheim, Andreas T. Echtermeyer. Measuring changing strain fields in composites with Distributed Fiber-Optic Sensing using the optical backscatter reflectometer. Composites Part B: Engineering. 2015; 74 ():138-146.
Chicago/Turabian StyleJon Harald L. Grave; Magnus L. Håheim; Andreas T. Echtermeyer. 2015. "Measuring changing strain fields in composites with Distributed Fiber-Optic Sensing using the optical backscatter reflectometer." Composites Part B: Engineering 74, no. : 138-146.
Unbalanced composite layups with bend-twist coupling show potential for aeroelastic tailoring in wind turbine blades. Before these materials can be implemented, their responses to long term cyclic loading must be considered. This paper studies the fatigue characteristics of an unbalanced glass-carbon hybrid laminate with a [45glass/−45glass/24carbon/24carbon]s layup. Flexural fatigue was performed at 7 different load magnitudes up to 1 × 106 cycles to characterize the failure modes and fatigue life of the composite. Stiffness degradation occurred on the tension side due to matrix cracking and small regions of delamination on the glass plies, whereas the failure mechanism of the laminate was by delamination between the glass and carbon. S-N curves were generated from experimental results and static finite element analyses (FEA) based on interlaminar shear stresses and were compared with laminates from previous literature. It was determined that the interlaminar stresses were influenced more so by the lower stiffness of the unbalanced layup than by the induced torsional deflections: leading to the conclusion that bend-twist coupling had little influence on flexural fatigue of glass-carbon hybrid composites.
Kevin B. Cox; Nils-Petter Vedvik; Andreas T. Echtermeyer. Flexural Fatigue of Unbalanced Glass-Carbon Hybrid Composites. Journal of Solar Energy Engineering 2014, 136, 041011 .
AMA StyleKevin B. Cox, Nils-Petter Vedvik, Andreas T. Echtermeyer. Flexural Fatigue of Unbalanced Glass-Carbon Hybrid Composites. Journal of Solar Energy Engineering. 2014; 136 (4):041011.
Chicago/Turabian StyleKevin B. Cox; Nils-Petter Vedvik; Andreas T. Echtermeyer. 2014. "Flexural Fatigue of Unbalanced Glass-Carbon Hybrid Composites." Journal of Solar Energy Engineering 136, no. 4: 041011.
Kh Leong; Professor Ag Gibson; Professor At Echtermeyer. Guest editorial. Journal of Reinforced Plastics and Composites 2014, 33, 505 -505.
AMA StyleKh Leong, Professor Ag Gibson, Professor At Echtermeyer. Guest editorial. Journal of Reinforced Plastics and Composites. 2014; 33 (6):505-505.
Chicago/Turabian StyleKh Leong; Professor Ag Gibson; Professor At Echtermeyer. 2014. "Guest editorial." Journal of Reinforced Plastics and Composites 33, no. 6: 505-505.
Bonded patch repairs are an efficient repair method for corroded or cracked metal structures, if welding is inconvenient. Avoiding the fire hazard of welding is a major reason for using patch repairs, but it can also be reduced distortions of the metal parts, protecting heat sensitive materials or equipment near the repair such as cables and so on. The lack of guidelines for performing such repairs has been a major hindrance for using this technology. A new recommended practice ‘Design, Fabrication, Operation and Qualification of Bonded Repair of Steel Structures’ has been published addressing: when a repair can be applied, which failure mechanisms need to be addressed, which material properties are needed, fabrication-related issues and in-service inspection. This paper will give a brief introduction to the document and its application areas.
Andreas T Echtermeyer; Dag McGeorge; Jon Harald L Grave; Jan Weitzenböck. Bonded patch repairs for metallic structures – A new recommended practice. Journal of Reinforced Plastics and Composites 2013, 33, 579 -585.
AMA StyleAndreas T Echtermeyer, Dag McGeorge, Jon Harald L Grave, Jan Weitzenböck. Bonded patch repairs for metallic structures – A new recommended practice. Journal of Reinforced Plastics and Composites. 2013; 33 (6):579-585.
Chicago/Turabian StyleAndreas T Echtermeyer; Dag McGeorge; Jon Harald L Grave; Jan Weitzenböck. 2013. "Bonded patch repairs for metallic structures – A new recommended practice." Journal of Reinforced Plastics and Composites 33, no. 6: 579-585.
A brief overview is given on how design standards are written. Static strength, fatigue, stress rupture, damage tolerance and the effect of the environment are addressed. Examples are given to show how durability is or can be addressed in design standards. Extensive testing is required today to certify long-term properties. Suggestions for research topics to reduce the test effort are discussed.
Andreas T. Echtermeyer. Integrating Durability in Marine Composite Certification. Internal Variables in Thermoelasticity 2013, 179 -194.
AMA StyleAndreas T. Echtermeyer. Integrating Durability in Marine Composite Certification. Internal Variables in Thermoelasticity. 2013; ():179-194.
Chicago/Turabian StyleAndreas T. Echtermeyer. 2013. "Integrating Durability in Marine Composite Certification." Internal Variables in Thermoelasticity , no. : 179-194.