Composite Bars Research Articles

Prediction of elastic wave propagation in composite bars using deep learning techniques

In this work, we developed a deep learning model based on a multilayer perceptron to predict the elastic wave output from composite bars. The model takes a vector representing the microstructure of the composite and the input wave applied at the left edge of the bar as features, with the target being the output elastic waves collected at the right edge of the bar. To train the model, we randomly generated composite bars with corresponding input waves and simulated them using finite element modeling. The results indicate that the proposed method can accurately and efficiently predict the output elastic waves.

Прогнозирование значений предела прочности при растяжении и модуля упругости композитной арматуры большого диаметра по косвенным признакам

Purpose: To consider the problems of experimental determination of elastic and strength properties of largediameter composite polymer glass fiber reinforced plastic rebar (FRP-rebar). To analyze the state of the issue, to make an overview of existing methods for determining elastic and strength properties of FRP-rebar. To show the necessity of developing methods of predicting the large-diameter FBR-rebar elastic and strength properties by means of indirect measurement methods. To carry out a series of tensile tests of FRP-rebar and to calculate the elastic-strength characteristics values using the rule of mixtures for composite materials. To make a comparative study of data obtained by experimental and analytical methods. Methods: Comparative analysis of the FRP-rebar elastic-strength characteristics calculated values with experimental data. Results: The need to improve the existing regulatory method for determining the elastic-strength characteristics of composite reinforcement bars is indicated. Calculation formulas of analytical prediction of the ultimate tensile strength and elastic modulus of FRP-rebar have been established. The calculated values obtained have been verified. The need of additional tests to build a statistical database has been identified. Practical significance: The proposed method for indirect measurement of FBR-rebar properties can be recommended for further experimental testing to reduce the risk of obtaining error values of elastic and strength characteristics of largediameter FRP-rebar when conducting direct experiments.

Experimental study on precast concrete columns reinforced with bundled SFCBs under horizontal cyclic loading

The poor corrosion resistance of steel bars limits the potential application of precast concrete structures. A promising solution is the use of steel-fiber reinforced polymer (FRP) composite bars (SFCBs) as reinforcements. SFCBs consist of an inner steel bar and an outer layer of FRP, providing excellent durability and customizable post-yield stiffness. The fabrication process of precast concrete structures can be more efficient by the utilization of bundled reinforcement and the deformation capacity can be enhanced by the weakening of the bond behavior. This paper describes a quasi-static test conducted on five precast concrete columns reinforced with bundled SFCBs (PCC-B-SF), as well as one conventional reinforced concrete column. The variables of the experiment contained the number of bars in each bundle (one (SF-1-P), two (SF-2-P), and three (SF-3-P)) and the construction method used (cast-in-place, partial grouting assembly, or full-length grouting assembly). The failure modes, hysteretic behavior, energy dissipation, residual deformation, and plastic hinge length were investigated. The results show that increasing the number of bars in each bundle of PCC-B-SFs leads to higher deformation capacity, energy ductility and self-centering ability. The ultimate deformation of SF-3-P was approximately 43.8% higher compared to the single-bar reinforced concrete column. Furthermore, the energy ductility of SF-2-P, SF-3-P, and SF-3-PL (with full-length grouting) was 16.1%, 20.7%, and 79.2% higher compared to SF-1-P. However, increasing the number of bars in each bundle may have a negative impact on energy dissipation. With full-length grouting, the highly bundled PCC-B-SF (consisting of three or more bars in one bundle) was found to enhance the bearing capacity and prolong plastic hinge regions. These findings suggest that the performance of PCC-B-SFs can exceed that of cast-in-place concrete columns.

Tribological characterization of laminated hybrid AA1050/TiC/Graphite composite bars

Hybrid composites (HC) refer to a type of material that combines aluminum (Al), titanium carbide (TiC), and graphite (Gr) at the nano level. These HC have shown promise in applications requiring high strength, wear resistance (WR), and tribological performance, such as automotive, aerospace, and industrial sectors. In this study, these HC are made using a combination of Powder metallurgy (PM) and accumulative press bonding (APB) processes have been developed. This is the first time that the wear resistance of a hybrid metal matrix composite fabricated with Gr as a solid lubricant has been done and thid is the novelty of this study. In fact, the presence of TiC nanoparticles (NP) provides improved mechanical properties, such as hardness (Hr), strength, and WR for HC. On the other hand, Gr acts as a solid nano-lubricant (NLU) in HC, reducing friction and WR during sliding contact. The presence of Gr-NP also helps to form a durable Gr-nanolayer on tribo surfaces and further improves the WR of HC. This study used a scanning electron microscope (SEM). The results demonstrated that incorporating TiC- NP reduced the WR rate and promoted NL development at extended sliding distances, creating a durable TiC/Gr HC on the TS. Finally, the improved WR of Al/TiC/Gr-HC can be attributed to the stability of the Gr-NL on the TS.

Systemic lupus erythematosus with high disease activity identification based on machine learning.

Clinical evaluation of systemic lupus erythematosus (SLE) disease activity is limited and inconsistent, and high disease activity significantly, seriously impacts on SLE patients. This study aims to generate a machine learning model to identify SLE patients with high disease activity. A total of 1014 SLE patients with low disease activity and 453 SLE patients with high disease activity were included. A total of 94 clinical, laboratory data and 17 meteorological indicators were collected. After data preprocessing, we use mutual information and multisurf to evaluate and select the importance of features. The selected features are used for machine learning modeling. Performance of the model is evaluated and verified by a series of binary classification indicators. We screened out hematuria, proteinuria, pyuria, low complement, precipitation, sunlight and other features for model construction by integrated feature selection. After hyperparameter optimization, the LGB has the best performance (ROC: AUC = 0.930; PRC: AUC = 0.911, APS = 0.913; balance accuracy: 0.856), and the worst is the naive bayes (ROC: AUC = 0.849; PRC: AUC = 0.719, APS = 0.714; balance accuracy: 0.705). Finally, the selection of features has good consistency in the composite feature importance bar plot. We identify SLE patients with high disease activity by a simple machine learning pipeline, especially the LGB model based on the characteristics of proteinuria, hematuria, pyuria and other feathers screened out by collective feature selection.

Bond strength of sand-coated deformed GFRP bars in UHPC, HPC, and NC

This paper focuses on evaluating the bond strength of sand-coated deformed Glass Fiber-Reinforced Composite (GFRP) bars in cement-based materials: Ultra-High Performance Concrete (UHPC), and High-Performance Concrete (HPC) and Normal Concrete (NC). A total of 48 pullout tests were conducted to examine the impact of parameters such as bond length (2.5db, 5db and 10db) and cover thickness (1db, 2db and 4.5db). Three common failure modes comprising bar pullout, rupture, and cover splitting were outlined, in which, pullout of GFRP rebars was controlled by shear damage between the resin and glass fibers, and UHPC splitting behaved with greater ductility than HPC or NC. The bond-slip curve of GFRP rebars involved the micro-slippage branch, the slippage branch, the exponentially descending branch, and the residual branch with oscillation characteristics. In comparison with HPC and NC, GFRP bars in UHPC showed 27.9%-72.6% and 130.5%-164.2% increases in bond strengths, respectively. Moreover, the higher bond strength was achieved in specimens with a smaller bond length or greater cover thickness. Specifically, bond strengths in samples having covers of 4.5db and 2db were enhanced by 30.8%-53.4% and 16.2%-26.8% to those with a cover of 1db. Furthermore, the bond strength calculation formula for GFRP rebars in UHPC was established and validated using the existing tests, and some design recommendations were presented.

Study on Deterioration Characteristics of a Composite Crossarm Mandrel in a 10 kV Distribution Network Based on Multi-Factor Aging.

This paper presents a study that conducted 5000 h of multi-factor aging tests on 10 kV composite crossarms, considering the natural environment in coastal areas and actual power line operations. Various aging conditions, such as voltage, rain, temperature, humidity, salt fog, ultraviolet light, and mechanical stress, were applied during the tests. The research initially analyzed the influence of multi-factor aging on the bending and tensile properties of the full-size composite crossarm. Subsequently, a detailed investigation was carried out to assess the impact of aging on the mechanical properties, electrical insulation properties, and microscopic characteristics of the composite crossarm core bar. Results indicated that the tensile strength and bending strength of the full-size composite crossarm mandrel experienced minimal changes after aging, remaining well within operational requirements. However, the silicone rubber outer sheath's hydrophobicity decreased, leading to the appearance of cracks and holes on the surface, which provided pathways for moisture and salt infiltration into the mandrel. As a consequence, the bending strength and shear strength of the mandrel material were reduced by 16.5% and 37.7%, respectively. Moreover, the electrical performance test demonstrated a slight change in the mandrel's leakage current, while the electrical breakdown strength decreased by 22.8%. Microscopic analysis using SEM, three-dimensional CT, and TGA revealed that a small amount of resin matrix decomposed and microcracks appeared on the surface. Additionally, the fiber-matrix interface experienced debonding and cracking, leading to an increased moisture absorption rate of the mandrel material.

Crack monitoring strategy for concrete structures in various service conditions via multiple CNT-CF/cement composite sensors: Experiment and simulation approaches

A crack monitoring strategy using parallelly-arranged multiple conductive cement composites for reinforced concrete was verified through a series of experiments and simulations. First, the electrical resistances of various locations of the mortar embedding the CNT-CF/composites were measured along with changes in humidity. Then, shear and flexural cracks were generated through a bending test of the reinforced mortar in which the CNT-CF/cement composite bars were embedded. The change in resistance of the composite bars themselves and between adjacent composite bars before and after cracking was measured. Differences in the results with the cracks in dried, wet, and also self-healing conditions were compared. Additionally, a finite element simulation on the electrical resistance under the experimental conditions was conducted to better understand the measurement results. Based on these experimental and simulation results, the strategy for monitoring structural damage under various operating scenarios was discussed. It was possible to monitor cracks of the reinforced mortar by detecting the increases and/or fluctuations in resistances of the composite bars themselves and between adjacent composite bars.

Mechanical properties and failure mechanism analysis of basalt-glass fibers hybrid FRP composite bars

In order to solve the defect of insufficient performance of the single fiber reinforced plastic (FRP) bars. The basalt fibers and glass fibers are prepared into the basalt-glass fibers hybrid FRP composite bars (B/G hybrid FRP bars) in this paper. The failure mechanism of basalt-glass fibers hybrid FRP composite bars is analyzed by the finite element method. The main failure factors include not only fiber breakage but also the separation of the interface between the two fibers. The mechanical properties of basalt-glass fibers hybrid FRP composite bars in the alkaline environment are predicted by simulation. The tensile properties, elongation properties, pseudo ductility stage length, and yield stress reduction of basalt-glass fibers hybrid FRP composite bars under different fiber volume ratios are investigated by tensile tests. The results show that when the volume ratio of glass fiber to basalt fiber is 7:3, the ultimate strain reaches 2.57%. When the volume ratio of glass fiber to basalt fiber is 9:1, the ultimate strain reaches 3.06%, with a difference of 0.49%. In addition, the yield stress reduction stage in basalt-glass fibers hybrid FRP composite bars is also affected by the volume ratio of hybrid fibers. When the volume ratio of glass fibers to basalt fibers is 9:1 and 7:3, the difference in ultimate tensile strength and the difference in yield stress reduction stage of the two are 185.85 MPa and 145.09 MPa, respectively. In addition, the optimal volume ratio range suitable for different situations is summarized in the study. When glass fiber accounts for 68.9–100% of the total integral number of basalt-glass fibers hybrid FRP composite bars, the tensile and extension properties of basalt-glass fibers hybrid FRP composite bars have different degrees of change.

Development and Mechanical Property Analysis of a Novel Uplift Pile Incorporating Composite Anchors

This paper presents a novel design for uplift piles incorporating a composite-anchor system. The composite-anchor system consists of steel strands, a non-expansion grouting body, and a high-strength steel pile. The aim of this design is to enhance the mechanical performance, durability, and economic efficiency of uplift piles. To evaluate the performance of the new pile, three sets of full-scale load tests were conducted, focusing on their in situ capacity, deformation, and stress characteristics. Despite a significantly lower reinforcement ratio of 0.75% compared to conventional piles with a ratio of 3.84%, the new uplift piles exhibit an exceptional uplift bearing performance. The utilization of the lateral friction resistance of the lower pile body is significantly improved, leading to enhanced load distribution and stress transfer mechanisms. Furthermore, a numerical model was developed and validated against the experimental results, demonstrating its reliability in simulating the bearing characteristics of the new uplift piles. The multi-interface design of the composite-anchor system ensures the efficient transmission of internal forces induced by external uplift loads, resulting in an improved stress state within the pile body. Moreover, the multi-layer structure of the composite main bar enhances the durability of the uplift piles. In comparison to conventional piles, the new uplift pile design offers substantial advantages, including an 80% reduction in reinforcement ratio, a 65% reduction in reinforcement cage welding, a cost reduction of approximately 30%, and a shortened construction time by around 20%. These findings highlight the potential of the new composite-anchor-pile design to revolutionize the field of uplift pile applications, offering improved efficiency and effectiveness.

Ductility improvement of metallic bars by bioinspired chiral microstructures

Improving the deformability of metallic materials is of paramount importance in engineering practice. Inspired by the tendrils–pole structures widely existing in the plant kingdom, we present a high-performance design of chiral composite structures in this study. Through wrapping fibers spirally on the surface of a metallic bar or embedding helical fibers into its body, the fracture strain of the bar can be increased greatly. Theoretical analysis and numerical simulations are combined to investigate the mechanical behavior of the designed composite. The effects of the number, geometry, and distribution of fibers on the elastoplastic responses of the composite bar are examined. Failure mechanisms of the bar are revealed. The results show that the helical fibers can suppress the occurrence of strain localization bands, leading to the improvement of structural ductility. The findings are verified by experimental measurement. The mechanical property of the proposed structures can be easily tuned by changing the microstructural parameters, and thus this strategy can be applied in various structures.

Seawater sea-sand concrete columns using durable and ductile steel-FRP composite bars and FRP ties: A promising hybrid scheme for marine engineering

To overcome corrosion of steel bar and scarcity of freshwater and river sand, durable and ductile steel-FRP composite bar (SFCB) provides a promising longitudinal reinforcement alternative in seawater sea-sand concrete (SWSSC) columns for marine infrastructures. The unique mechanical properties and lower compressive strength of SFCB inevitably influence axial compressive performance of column. However, very few studies on axial compressive performance of hybrid longitudinal SFCBs and FRP ties reinforced concrete (hybrid-RC) columns lead to a lack of valuable experimental observations and failure mechanisms. Here, an experimental investigation of axial compressive performance for hybrid-RC columns is conducted. Results indicate that SFCB has a bilinear stress–strain characteristic with high elastic modulus under compression and can maintain its integrity until concrete crushing. Using SFCB as longitudinal reinforcement leads to satisfactory axial compressive behavior including high strength and great ductility for columns. Nevertheless, FRP ties show low confinement efficiency since the worse mechanical properties of bent portion and the slipping of lap splice. With the experimental and theoretical analysis for hybrid-RC columns, the prediction model of axial load capacity is developed and validated preliminarily, showing great accuracy. These findings provide a meaningful experimental basis and safe design tactics for this hybrid reinforcement scheme of SWSSC.

Axial-flexural performance of columns reinforced by steel-FRP composite bars and FRP ties

The ductile and corrosion-resistant steel-FRP composite bar (SFCB) is a promising longitudinal reinforcement for marine engineering in harsh environments. However, the study about the axial-flexural performance of longitudinal SFCBs reinforced concrete columns, especially combined with corrosion-resistant FRP ties, is very limited. The lack of valuable experimental observations and design methods seriously limits its design and application. Here, 15 square concrete member specimens with different reinforcement types are tested under concentric compression, eccentric compression, and pure flexural loading, to investigate the effect of longitudinal SFCB and FRP tie on the axial-flexural behavior of columns. Results show that the yielding characteristic of longitudinal SFCB leads to two representative failure modes (tension-controlled and compression-controlled failure). Using equal-stiffness SFCB to replace steel bar contributes to a better axial-flexural behavior of columns, including the same failure mode, similar deformation, and higher load capacity. Furthermore, a theoretical model that considers the unique constitutive relationship of SFCB and confinement conditions of different ties is developed to predict the failure modes and axial-flexural capacity of columns, showing great accuracy. These findings provide a valuable experimental basis and safe design tactics for this corrosion-resistant and ductile hybrid reinforcement scheme of marine infrastructure.

Use of bending test to determine the tensile strength and elastic modulus of GFRP bars

Fiber-reinforced polymer (FRP) composite bars have been increasingly employed to reinforce concrete members when the use of traditional steel bars would represent an issue for the durability of the structure. In fact, FRP bars have high strength-to-weight ratio, do not suffer of corrosion, and do not conduct electricity. Mechanical characterization of composite bars is complex due to the remarkable difference between bar properties in the direction parallel and orthogonal to the fiber. Therefore, direct tensile testing of FRP bars requires proper specimen preparation, which usually involves expensive bonding of metal pipes at the specimen ends. In this paper, a 3-point bending test is proposed as a possible alternative to the direct tensile test to obtain a quick and reliable estimate of the bar tensile strength and elastic modulus. An analytical model that accounts for bar shear deformation and large displacements is used to describe the specimen bending behavior. Forty bending tests of glass FRP (GFRP) bars with thermosetting or thermoplastic resin and four different diameters are presented and used to validate the test set-up and analytical model proposed. The results are compared with those of corresponding direct tensile tests showing the validity of the proposed bending test.

Effects of an Acidic Environment on the Strength and Chemical Changes of Resin-based Composites.

The objective of this study was to evaluate the aging effects of long-term exposure to acidic beverages on the flexural strength (FS) and chemical reactions of two resin-based composites (RBCs) and one giomer. The FS of composite specimen bars (2 mm × 2 mm × 25 mm) was measured using a universal testing machine at various levels of thermocycling (TC; 0, 10,000, 50,000, and 100,000 cycles) in two beverages with different pH values (distilled water [DW], pH 7.0; Coca-Cola, pH 2.4-2.8). The FS data were analyzed using three-way analysis of variance with the post hoc Tukey test and t-test at a significance level of a=0.05. In DW, the FS of an RBC and a giomer did not decrease until 10,000 cycles. The other RBC, Z250, decreased rapidly until 50,000 cycles (p<0.05), followed by no additional decrease until 100,000 cycles. In Coca-Cola, the FS of two RBCs and a giomer decreased more rapidly than in DW from 10,000 cycles (t-test, p<0.05). In Coca-Cola, the increased porosity observed in scanning electron microscopy (SEM) images, the changes of the hydroxyl peak at 3340 cm-1 and ester peak at 1730-1700 cm-1 in Fourier-transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR) spectra, and the continuous increase of the Si-O/Si-C peak height ratio from 10,000 cycles to 100,000 cycles in X-ray photoelectron spectroscopy (XPS) suggested an increased loss of silane-carbon bond between the matrix and fillers of the Z250 RBC, compared to those in DW. In conclusion, when TC was performed in DW, unreacted monomers and a coupling agent were washed out, which caused porosity and reduced FS. In Coca-Cola, acidic conditions accelerated the removal of the matrix through the hydrolysis reaction at the ester groups, resulting in more porosity and a faster decrease in FS than in DW.

Effect of Turning Parameter and Fiber Pullout on Machinability of Unidirectional EGFRP under Cryogenic Condition

The non-homogeneous and anisotropic nature of composites poses challenges during machining, requiring the use of specialized cutting tools. GFRP materials were selected for their excellent elasticity, corrosion resistance, and high strength, making them ideal for applications in the aerospace and automotive industries. In this work, the surface quality of UD-GFRP composite bars during CNC machining in diverse machining conditions (dry, wet, and cryogenic) was investigated while considering the fiber-pullout issue. The UD-EGFRP composite materials have been machined with a polycrystalline diamond tool. The Taguchi-L9 orthogonal-array technique is used to investigate and further analysis. Three independent-variables feed rate, rotational speed or cutting speed, and depth of cut have been taken into account for their optimal design to get better machinability of EGFRP. This study also investigates the delamination criterion in composites and establishes the correlation between its input parameters and output responses. The findings revealed that cryogenic machining led to a notable improvement of 25.21% in surface roughness compared to the other lubrication methods. Also, the reduction from 84 µm to 34 µm in fiber-pullout signifies that cryogenic cooling effectively mitigated the occurrence of fiber-pullout.

Optimization of the First-Step Drawing Parameters for Platinum-Clad Nickel Bar Based on FEM Simulation

The first-step drawing process of the platinum-clad nickel composite bar was numerically simulated using DEFORM 3D finite element analysis software. The Taguchi method was used to study the effect of the first-step drawing parameters (the semi-angle of die α, the friction coefficient between the platinum tube and die μ1, the friction coefficient between the platinum tube and nickel rod μ2 and the outer diameter of the original platinum tube D) on the effective stress of platinum-clad nickel bar. Then, the optimal combination of parameters (D = 7.55 mm, μ1 = 0.2, μ2 = 0.3, α = 3°) was obtained. Furthermore, the results of the deformation behavior, cladding behavior, stress effectiveness and the distribution of the damage of the composite bar using optimization schemes were compared and analyzed with Numerical Simulations 8, which showed the worst result. Meanwhile, the experimental results were in general agreement with the simulation results of optimal combination of parameters, indicating that our simulation results are plausible. This has certain guidance significance to improve the quality of platinum-clad nickel composite wires in actual production.

Designing composite poly-amide cord knitted fabrics for reinforcing concrete beams

Textile Composites is a resin system containing a textile fiber, yarn, or fabric system for special properties. Cord knit is a simple and economic and fast technique for producing tubular textile fabrics. This article studied the effect of some variables such as outer layer yarn count and core material of poly-amide cord knitted fabrics on its properties and applying it as a cord-knitted composite bar for reinforcing concrete. six samples with two different outer layer yarn counts (1200 and 2400 denier) and three different core materials (polyamide, fiberglass, and polyethylene 50%, and polypropylene 50%) were produced and tested, then inserted in epoxy to convert to a composite cord. The properties of composite cord knitted fabrics were tested. Then different numbers of bars were used (one bar, two bars, and three bars) from the highest properties cord knitted poly-amide composite fabrics for reinforcing concrete beams (50 cm*10cm*10cm), flexure of those beams were tested and it was found that using two bars from poly-amide composite has the highest effect on reinforcing concrete beams.

Lupus nephritis or not? A simple and clinically friendly machine learning pipeline to help diagnosis of lupus nephritis.

Diagnosis of lupus nephritis (LN) is a complex process, which usually requires renal biopsy. We aim to establish a machine learning pipeline to help diagnosis of LN. A cohort of 681 systemic lupus erythematosus (SLE) patients without LN and 786 SLE patients with LN was established, and a total of 95 clinical, laboratory data and 17 meteorological indicators were collected. After tenfold cross-validation, the patients were divided into training set and test set. The features selected by collective feature selection method of mutual information (MI) and multisurf were used to construct the models of logistic regression, decision tree, random forest, naive Bayes, support vector machine (SVM), light gradient boosting (LGB), extreme gradient boosting (XGB), and artificial neural network (ANN), the models were compared and verified in post-analysis. Collective feature selection method screens out antistreptolysin (ASO), retinol binding protein (RBP), lupus anticoagulant 1 (LA1), LA2, proteinuria and other features, and the hyperparameter optimized XGB (ROC: AUC = 0.995; PRC: AUC = 1.000, APS = 1.000; balance accuracy: 0.990) has the best performance, followed by LGB (ROC: AUC = 0.992; PRC: AUC = 0.997, APS = 0.977; balance accuracy: 0.957). The worst performance is naive Bayes model (ROC: AUC = 0.799; PRC: AUC = 0.822, APS = 0.823; balance accuracy: 0.693). In the composite feature importance bar plots, ASO, RF, Up/Ucr, and other features play important roles in LN. We developed and validated a new and simple machine learning pathway for diagnosis of LN, especially the XGB model based on ASO, LA1, LA2, proteinuria, and other features screened out by collective feature selection.

Combined experimental–numerical mode I fracture characterization of the pultruded composite bars

In this paper, pultruded GFRP bars are investigated to determine their fracture properties. The double cantilever beam test (DCB) is used to assess fracture behavior under mode I loading conditions. However, due to the presence of the R-curve effect (variable fracture energy dependent on the length of the crack), it is necessary to introduce a nonstandard approach to determine fracture properties. The mixed experimental–numerical approach is proposed to deal with this issue. Numerical simulations were carried out in Simulia Abaqus, and with Python scripting it was possible to generate models and obtain R-curve for the material. The numerical model built based on the experimental results has very good agreement with it (force–displacement and delamination length–time characteristics) which allows the use of the mentioned model in the analysis of more complex structures. Acoustic emission analysis was introduced as an auxiliary technique. The delamination obtained from both the numerical model and the experiment complies with the registered acoustic emission events. The proposed method can be used in preparing a material model for other composite materials, which display the presence of the R-curve effect.