Fatigue Behavior Of Composite Materials Research Articles

Fiber-Reinforced Thermoplastic Sucker Rods Provide Artificial Lift Efficiencies

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23949, “Fiber-Reinforced Thermoplastic Sucker Rods Providing High-Strength, Lightweight, Low-Cost, and Environmentally Responsible Artificial Lift Efficiencies,” by Jeff Saponja, SPE, Oilify, and Corbin Coyes, SPE, and Michael Conner, SPE, Q2 Artificial Lift Services. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ The complete paper focuses on the development of fiber-reinforced thermoplastic (FRTP) sucker rods, highlighting their potential advantages and challenges, for rod pumping (in general) and for offering an earlier transition from electrical submersible pump (ESP) pumping or gas lifting to reliable deep high-rate rod pumping. A unique feature of an FRTP composite rod is its remarkably high shear failure resistance compared with that of a thermoset composite rod. A high shear-failure resistance means the rods have compressional loading tolerance and that an entire sucker rod string could be comprised of FRTP sucker rods. Introduction Sucker rods made from steel are relatively heavy. Extensive well-specific designs require tapering of rod strings to optimize the overall sucker rod string weight relative to the strength and fatigue requirements and consideration of the dynamic loadings from accelerations and decelerations of the rods and fluids, frictional effects, and structural or power limitations of the pump jack or unit at surface. Steels suffer from corrosion risks. Corrosion, which rapidly can accelerate fatigue failure, often is the root cause of sucker rod failure. Fiber-reinforced composites (i.e., fibers surrounded by or wetted by a resin matrix) have gained considerable popularity because they can be tailored to have outstanding mechanical, thermal, and physical properties, and have superior material mechanical properties to metal. The fatigue behavior of composite materials and structures is complex because composites fail by a series of, or collection of, damage mechanisms, including fiber breakage, matrix cracking, fiber/matrix debonding, delamination, and the effect of shear-induced damage on cracks. Cracking can be slowed somewhat if the reinforced fibers are of high stiffness. Composite materials can offer a lower environmental footprint over their entire life cycle. They can require less energy to manufacture, thereby reducing CO2 emissions. A high strength/weight ratio offers less energy consumption during operational use, further reducing CO2 emissions. Composite materials can be recycled and reused. Composite sucker rods, in the form of thermoset fiberglass sucker rods, have offered a high strength/weight ratio with greater corrosion tolerance, but they are too stretchy from a low glass fiber tensile modulus of elasticity for deep high-rate rod pumping and when a high production-rate decline is likely. This limitation results in a large bottomhole pump-stroke variability as operating conditions change. Such rods have low tolerance to compressional and impact loads, forcing a larger proportion of a sucker string to remain as steel. They are also more costly than steel rods. For sucker rod pumping, an ideal composite rod should tolerate compressional loads and feature high impact resistance and high fatigue endurance with an ability to limit or control crack formation. A composite material that potentially offers these important sucker rod properties is FRTP.

Failure Analysis and Fatigue Behavior of Natural Fibers Reinforced Composite Materials under Cyclic Loading

This research investigates the failure analysis and fatigue behavior of composite materials reinforced with a combination of glass fiber, sisal fiber under cyclic loading conditions. The study aims to elucidate the synergistic effects of these diverse natural fibers in enhancing the mechanical properties and fatigue resistance of the composite materials. Experimental methods, including mechanical testing and microscopic analysis, are employed to discern the individual contributions of each fiber type and their combined influence on failure modes and fatigue life. The project seeks to provide valuable insights into the optimal integration of glass, sisal to achieve a balanced composite material that exhibits superior durability and performance. The outcomes of this research contribute not only to the advancement of natural fibers composites but also offer practical guidelines for designing resilient materials for various engineering applications.

Stress and strain calculation method for orthotropic polymer composites under axial and bending ultrasonic fatigue loads

Accelerated fatigue testing is one potential solution to evaluate the very high cycle fatigue behavior of composite materials within a reasonable amount of time. The ultrasonic fatigue testing methodology can be adopted to realize fatigue experiments up to 109 cycles at 20 kHz, compared to conventional fatigue experiments usually carried out between 5–50 Hz. The determination of cyclic stresses during ultrasonic loading remains to be one of the major challenges. The cyclic stresses during ultrasonic fatigue loading were investigated for a carbon fiber 5H satin fabric reinforced in Polyetherketoneketone (CF-PEKK) composite material. Two experimental setups were developed to perform ultrasonic testing under uni-axial and three-point bending loading conditions. A 3D-Scanning Laser Doppler Vibrometer (3D-SLDV) and a single-point Laser Doppler Vibrometer (LDV) were integrated into the test systems to measure the oscillation displacement of the CF-PEKK specimens during ultrasonic cyclic loading. These displacement measurements were used to calculate the resulting strains and stresses under elastic loading conditions. The experimental results were found to be in good agreement with those obtained from finite element models, providing evidence for applying the proposed method.

Effects of an enhanced fibre–matrix adhesion on the fatigue behaviour of composite materials under very high cycle fatigue

The fatigue behaviour of two glass fibre-reinforced epoxy composite materials with a cross-ply layup is investigated in the very high cycle fatigue (VHCF) regime with up to 10^8 load cycles. In addition to the influence on the fatigue lifetime, different materials can also cause a different damage phenomenology. One reference fibre (OC111A) and one fibre with increased fibre–matrix adhesion (SE2020) are tested. The experimental and numerical investigations show that the damage threshold is shifted to higher loads with increased fibre–matrix adhesion, but the damage mode of delaminations becomes more important.

A numerical investigation of the interaction between interlaminar and intralaminar damages in a fatigued composite panel

AbstractThe fatigue behavior of composite materials is still a very challenging issue for the scientific community. So far, several numerical methodologies allow us to faithfully simulate the propagation of delamination due to fatigue. However, the reduction of material properties due to the applied cyclic load should be considered. The main objective of this work is to investigate the role of the material property degradation and the intralaminar damages on the propagation of delamination in composite laminates under fatigue loads. The numerical tool FT‐SMXB, based on the Paris Law and virtual crack closure technique, for the mimic of fatigue‐driven delamination, has been integrated with a user material subroutine, based on the generalized residual material property 7degradation model and the Hashin fatigue failure criteria. Typical aeronautical stiffened panel has been considered as test case. Matrix damages and strength degradation due to fatigue cycles have been found to influence the propagation of delamination.

Modeling the Effect of Stress Ratio, Loading Frequency and Fiber Orientation on the Fatigue Response of Composite Materials.

Fatigue life models are widely used to predict the fatigue behavior at arbitrary cycle counts of composite structures subjected to cyclic or highly dynamic loads. However, their predictive capacity and determination of model parameters are strongly dependent on loading conditions and large experimental efforts. This research aims to develop a new model which uses a single model parameter to predict the variation trend and distribution pattern of fatigue experimental data points subjected to different stress ratios, loading frequencies and fiber orientations. Validation of the model with several sets of experimental data shows that the proposed model is capable of adequately considering the effects of stress ratio, loading frequency and fiber orientation on the fatigue behavior of composite materials and correctly predicting the variation trend of the experimental data points using only one set of model parameters regardless of stress ratios, loading frequencies and fiber orientations.

Effect of SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> Hybrid Nano Materials on Fatigue Behavior for Laminated Composite Materials Used to Manufacture Artificial Socket Prostheses

Most artificial socket prostheses are applied to fatigue load; therefore, more failure of socket prostheses occur due to fatigue loading. Then, it was necessary to improve the fatigue characterizations of composite materials used to manufacture the artificial socket prostheses by using hybrid nanomaterials, with different types and amounts. So, this work suggested mixing two nanomaterials types to improve the mechanical and fatigue properties of composite materials. Therefore, the experimental work used to manufacture tensile and fatigue samples of composite with different nanoweight fraction effects, in addition to calculating the mechanical properties and fatigue behavior for its composite. There, strength and modulus of elasticity, in addition to, fatigue strength and life evaluating of composite with different nanomaterials mixing. Also, the numerical technique by using the finite element method is used to calculate fatigue life and strength of composite materials. Also, comparison fatigue results were calculated by experimental work with fatigue results evaluated by numerical technique to give the discrepancy for results evaluation. Hence, the comparison of results showed good agreement for the technique used to evaluate the fatigue behavior of composite materials with the nanoeffect, where, the maximum error did not exceed (11.86%). Finally, the results have shown that the reinforcement by mixing two Nanomaterial types lead to improvement in the mechanical properties and fatigue behavior to more than (35%) and increasing the mechanical properties and fatigue behavior to (10%) more than the increase of properties and fatigue characterizations reinforcement by one Nanomaterial type.

Fatigue and vibrational analysis of composite plates based on curve fitting method

In this paper studying the fatigue behaviour of race bicycle frames. After a literature study on the fatigue behaviour of composite materials in general, a model dependent on the decrease of firmness was proposed to gets to weakness conduct in bike outlines. To examine this model a fatigue test setup was studied. This specimen was made in accordance with glass fiber, aluminium & fly ash together which some extra features, which can serve for different concepts. The functionality of the setup was evaluated, and this proved to show good results. Also, a fatigue test was carried out on a bicycle and the proposed reduction of stiffness model was validated.

Fatigue of Composite Materials Subjected to Variable Loadings

A model describing the fatigue behavior of composite materials under variable loadings is presented. The approach is based on a two-parameter model fulfilling the principal responses’ features of composite materials subjected to constant amplitude cyclic loadings. It is shown that when coupled with the equivalent residual strength assumption the model can describe the strength degradation of composite materials subjected to variable amplitude loadings without simplifications or substantial reductions of the loading spectrum. Compared to the linear Miner’s rule, the results highlight the importance of the sequence of loads and the approach discriminates the ascending, descending and random patterns. It is shown that for the case under study the ordered descending (high to low) sequence showed the worst scenario in terms of damage accumulation extent, while the random spectrum resulted in an intermediate response between ordered ascending and descending sequences.

Fatigue of Composite Materials Subjected to Variable Loadings

In the present work, a model describing the fatigue behaviour of composite materials under spectrum loading is presented. The approach is based on a two-parameter model describing the strength degradation kinetics for fibre-reinforced materials subjected to cyclic loadings, both with constant and variable amplitudes. The point of strength of the presented approach is that it allows to consider cyclic loadings as they are, without simplifications or reductions. In particular, the analytical background of the model is based on the statements that govern the composites behaviour and focused on the issues related to this class of materials when subjected to fatigue. Then, the final step is the definition of a damage accumulation rule that goes over Miner’s rule unreliability when applied to fibre-reinforced materials. As a matter of fact, it allows to take into account the effects of different loading histories, underlining the importance of the sequence of loads application in the framework of the presented approach.

Fatigue damage behavior in carbon fiber polymer composites under biaxial loading

An investigation into the damage accumulation and propagation behavior in carbon fiber reinforced polymer (CFRP) composites under complex in-phase biaxial fatigue loading has been conducted. The goal is to capture early stage damage and obtain an improved understanding of damage propagation and associated degradation in material properties. Both cross ply and quasi isotropic laminate configurations have been studied and the tests were conducted under constant amplitude in-phase biaxial loading. An optimization technique was used to design the cruciform specimens for each stacking sequence. To understand the propagation of damage from the micro-to the macroscale, the fractured surfaces were analyzed, during various stages of fatigue, using electron microscope assisted fractography and a high-resolution camera. Material property degradation was determined by measuring the change in specimen stiffness to analyze the progression of fatigue damage and is correlated to the micro- and macroscale damage mechanisms and the biaxial fatigue loading parameters. The results provide insight into the initiation and propagation of damage mechanisms in CFRP composites which is essential to understanding the fatigue behavior of composite materials under complex multiaxial loadings.

Computationally efficient modelling of the fatigue behaviour of composite materials

Fatigue of composite structures is a complex process involving several types of failure. Existing approaches either neglect this complexity or require large computational effort. In this work, a simple progressive damage model including strength and stiffness degradation is implemented into finite element (FE) software. To reduce computational time, the major part of stress calculations is carried out by classical lamination theory. At single points of time, FE analysis is employed to support these calculations. The simplified model is tested against a reference model using FEA after each load cycle. Calculations are set up for a tensile specimen and a cap profile with quasi-isotropic layup. The simplified model using CLT is shown to be in good agreement with the reference while significantly reducing computational time.

A comparative study on low cycle fatigue behaviour of nano and micro Al2O3 reinforced AA2014 particulate hybrid composites

Aluminium based metal matrix composites have drawn more attraction due to their improved properties in structural applications for the past two decades. The fatigue behaviour of composite materials needs to be studied for their structural applications. In this work, powder metallurgy based aluminium (AA2014) alloy reinforced with micro and nano-sized alumina particles were fabricated and consolidated with the hot extrusion process. The evaluation of mechanical properties in the extruded composite was carried out. This composite was subjected to low cycle fatigue test with a constant strain rate. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) images were used to evaluate the fatigue behaviour of aluminium-nano composite samples. Enhanced mechanical properties were exhibited by the nano alumina reinforced aluminium composites, when compared to the micron sized alumina reinforced composites. The failure cycle is observed to be higher for the nano alumina reinforced composites when compared with micron sized alumina composites due to a lower order of induced plastic strain.

A review of thermographic techniques for damage investigation in composites

The aim of this work is a review of scientific results in the literature, related to the application of thermographic techniques to composite materials. Thermography is the analysis of the surface temperature of a body by infrared rays detection via a thermal-camera. The use of this technique is mainly based on the modification of the surface temperature of a material, when it is stimulated by means of a thermal or mechanical external source. The presence of defects, in fact, induces a localized variation in its temperature distribution and, then, the measured values of the surface temperature can be used to localize and evaluate the dimensions and the evolution of defects. In the past, many applications of thermography were proposed on homogeneous materials, but only recently this technique has also been extended to composites. In this work several applications of thermography to fibres reinforced plastics are presented. Thermographic measurements are performed on the surface of the specimens, while undergoing static and dynamic tensile loading. The joint analysis of thermal and mechanical data allows one to assess the damage evolution and to study the damage phenomenon from both mechanical and energetic viewpoints. In particular, one of the main issues is to obtain information about the fatigue behaviour of composite materials, by following an approach successfully applied to homogenous materials. This approach is based on the application of infrared thermography on specimens subjected to static or stepwise dynamic loadings and on the definition of a damage stress, ?D, that is correlated to the fatigue strength of the material. A wide series of experimental fatigue tests has been carried out to verify if the value of the damage stress, ?D, is correlated with the fatigue strength of the material. The agreement between the different values is good, showing the reliability of the presented thermographic techniques, to the study of composite damage and their fatigue behaviour.

Fatigue Behaviour of Glass Fibre Reinforced Composites for Ocean Energy Conversion Systems

The development of ocean energy conversion systems places more severe requirements on materials than similar land-based structures such as wind turbines. Intervention and maintenance at sea are very costly, so for ocean energy supply to become economically viable long term durability must be guaranteed. Cyclic loading is a common feature of most energy conversion devices and composites are widely used, but few data are available concerning the fatigue behaviour in sea water of composite materials. This paper presents the results from an experimental study to fill this gap. The fatigue behavior of composite materials reinforced with different types of glass fibre is characterized in air and in sea water; the influence of testing in sea water rather than air is shown to be small. However, sea water ageing is shown to reduce the fatigue lifetime significantly and strongly depends on matrix formulation.

A hybrid S–N formulation for fatigue life modeling of composite materials and structures

A semi-empirical S–N formulation for the modeling of the constant amplitude fatigue behavior of composite materials and structures is introduced in this paper. The new S–N formulation is based on the commonly used exponential and power law fatigue models. It is a hybrid formulation combining the two existing models in order to improve their modeling accuracy in the low and high cycle fatigue regions. This formulation was applied to a number of fatigue databases for different composite materials and structural elements in order to simulate their fatigue behavior. The modeling accuracy of the hybrid model was compared to the accuracy of commonly used S–N models for composite materials. As proved, the hybrid model performs better in the majority of the examined cases and is able to overcome the disadvantages of previously developed models without introducing any complexity in the fitting procedure.

Fatigue behavior of composite materials made from waste plastics

In this paper fatigue behavior of composite materials made from waste plastics such as polyethylene and polypropylene is summarized. Fatigue strengths of polyethylene and polypropylene matrix composite materials with various kinds of fillers such as fly ash, calcium carbonate, glass fiber, glass powder, talc and wood are demonstrated. Among the composite materials made from pallets by use of newly manufacturing system for waste plastics the polyethylene composite materials with 20 wt% fly ash only showed higher fatigue strength than that of polyethylene waste plastics. However the polypropylene composite materials with fillers such as 25 wt% talc and 20 wt% glass fiber made from injection molding showed higher fatigue strengths than that of polypropylene material. It can be concluded from detailed fracture surface observations that the tight interface between polyethylene and polypropylene matrix and fillers can provide composite materials with high fatigue strength by use of newly developed manufacturing systems for waste plastics.

Multiscale study of fatigue behaviour of composite materials by χ-rays computed tomography

The study of microstructure and damage mechanism of elastomeric matrix (EMC), wooden plastic (WPC) and also metal matrix (MMC) composites involves a complicated interplay between material properties and service conditions. So, the study of texture deformation and fatigue behaviour of EMC, WPC and MMC specimens is of considerable practical interest. On the other hand, the occurrence of defect in specimens in working conditions is an important problem. It is necessary to improve the microstructure for delaying instability, in order to obtain a higher service capacity. This paper presents the in-situ observation of damage by using χ-rays computed tomography (CT) Medical Scanner installed in the ITMA research centre for evaluating the fatigue behaviour of EMC, WPC and MMC. A tomographic inner-health analysis will be given from 2D slices of the examined parts in laboratory scale on the WPC, EMC and MMC specimens used in automotive industry and aeronautical fields.

A Model for Fatigue Life In CFRP Laminates with Impact Damage

This paper presents the fatigue behavior of composite materials with impact-induced damage. The impact damage parameter is proposed to evaluate the effect of impact damage on fatigue life. Subsequently, a new model is developed to predict the fatigue life of impacted composite materials. Also, a stochastic model is proposed to describe the variation of fatigue life due to the material nonhomogeneity. For these models, the fatigue tests were performed on the unimpacted and impacted composite materials, The effect of impact damage on fatigue life can be characterized by the impact damage parameter. Additionally, the results by the present fatigue life prediction model agree will with experimental results regardless of applied impact energy. Also, the variation of fatigue life can be described by the present stochastic model and is reduced with applied impact energy.

Fatigue Life of Graphite/Epoxy Laminates Subjected to Tension-Compression Loadings

A recent two-parameter fatigue model, aimed at the predictionof the fatigue behaviour of composite materials, was applied to fatigueresults available in the literature, concerning graphite/epoxy laminatessubjected to tension-compression loadings. It was found that the model,successfully applied in the case of tension-tension andcompression-compression fatigue, also works when the sign of stress isreversed during fatigue. However, the constants appearing in theproposed formula must be evaluated anew when the loading mode changesfrom pure tension to tension-compression. The probability of failure infatigue is predicted with reasonable accuracy by the model, which isvery conservative in calculating the residual strength after a givennumber of cycles.