Fiber-matrix Interface Research Articles

A DIC-FEM hybrid method for measuring strains near fiber-matrix interface of CFRP cross section

A DIC-FEM hybrid method is proposed to capture micro-scale deformation behavior near the fiber-matrix interface by combining displacement distributions measured using digital image correlation (DIC) with finite element method (FEM) analysis. Images of CFRP cross section with fine random pattern before and after deformation are taken with a laser microscope. The in-plane displacement components near the interface of fiber and matrix are obtained using digital image correlation and they are used as the input of the hybrid method. Not only the displacement distributions but the strain fields are determined using the proposed hybrid method, based on the superposition principle, so that the same distributions are obtained as those obtained by the measurement. The proposed DIC-FEM hybrid provides the strains near the interface between fiber and matrix, compensating for the insufficient resolution of microscope images.

Bio-inspired widening concrete using cellulose nanofiber to enhance multiscale Fiber–Matrix interface

The cracking issue at the bonded interface due to the differing shrinkage performances of newly poured concrete and existing concrete poses a significant threat to the safe service of composite structures. Inspired by the musculoskeletal system, we propose the use of multiscale hybrid reinforced concrete materials, incorporating basalt fiber (BF), polypropylene (PP) fiber, and cellulose nanofiber (CNF), for bridge widening structures. Experimental investigations were carried out to assess the bond splitting tensile strength, diagonal shear strength, crack resistance, development of drying shrinkage deformation, and the propagation behavior of restrained shrinkage-induced cracks in both new and old concrete reinforced with single and hybrid combinations of BF, PP fiber, and CNF. The microstructure, phase composition, and pore structure evolution of BF, PP fiber, and CNF-reinforced concrete were observed and analyzed using scanning electron microscopy, thermogravimetric and derivative thermogravimetric analysis, nuclear magnetic resonance, and mercury intrusion porosimetry. The results indicate that the incorporation of BF, PP fiber, and CNF exhibits excellent synergistic effects, improving the bond and shrinkage performance of the concrete interface. As the CNF content increases, the macro fiber–matrix interface improves. This bio-inspired work will contribute to the development of strong, tough, and sustainable concrete for bridge widening structures.

High-temperature behaviour of geopolymer composites containing carbon fibre and nano-silica: Mechanical, microstructure, and air-void characteristics

The fly ash–ground granulated blast-furnace slag-based geopolymer (FSG) represents a groundbreaking material, offering a sustainable and environmentally friendly alternative to conventional construction materials. This paper presents a systematic experimental study on FSG reinforced with carbon fibre (CF, 0%–1.0%) and nano-silica (NS, 1%–3%) at high temperatures (20, 200, 400, 600, 800, and 900 °C). Various tests concerning appearance, residual strength, uniaxial tension, XRD, FTIR, TGA, SEM, and air-void characteristics were conducted to analyse thermal effects. The findings show that as temperature increases, the colour of the geopolymer transitions from dark grey to yellow grey. Enhanced geopolymerisation during thermal solidification from 20 to 400 °C significantly increases the compressive, flexural, and tensile strengths of the geopolymer. The addition of CF and NS improves the residual strength of geopolymers at high temperatures, with optimal concentrations found to be 0.6% for CF and 2% for NS. CF maintains its bridging effect at high temperatures, enhancing fibre–matrix bonding, while NS promotes the formation of additional hydration products on CF surfaces, thereby strengthening the material further. After exposure to 800 °C, despite a weakening of the fibre–matrix interface, the modified geopolymers (FSGC0.6 and FSGC0.6N2) exhibit finer air bubble chord lengths and superior air-void characteristics than the control group. This supports the theory that the synergistic action of CF and NS not only enhances geopolymerisation but also fills pores, thus limiting crack propagation and densifying the pore structure.

Micro-Macro Coupling Study on the Mechanical Properties of Continuous Fiber-Reinforced Composites.

As a key and weak point of continuous fiber-reinforced composites (CFRCs), the interface between the fiber and the matrix is vulnerable to failure under external loads, with its performance directly affecting the overall properties of CFRCs. Hence, a micro-macro coupling method that considered the microscopic properties of the interface was utilized to analyze and predict the mechanical properties of CFRCs more accurately. The microscopic mechanical parameters of the fiber-matrix interface, which were obtained using molecular dynamics, were transferred to the representative volume element (RVE). The stiffness matrix of the CFRC, required for the macroscopic finite element model, was then calculated using a unified periodic homogenization method based on the RVE and assigned to the finite element model for a macroscopic simulation. Nylon/continuous carbon fiber specimens were fabricated through additive manufacturing, with the tensile and bending strengths of the specimens obtained through tensile and three-point bending tests. The tensile strength of the experimental specimen was 200.1 MPa, while the result of the simulation containing the interface was 205.5 MPa, indicating a difference of less than 5% between the two. In contrast, the result of the simulation without an interface was 317.7 MPa, representing a high error of 58.7% compared with the experimental results. Moreover, the bending strength, Young's modulus, and flexural modulus results with and without an interface showed the same trend as that for the tensile strength. This illustrates the effectiveness of the proposed micro-macro coupling method for analyzing and predicting the mechanical properties of CFRCs.

Questioning the Representativeness of Damage Mechanisms in Single-Fiber Composites via In Situ Synchrotron X-Ray Holo-Tomography.

In fiber-reinforced polymer composites, the fiber-matrix interface controls stress transfer mechanisms, thereby affecting mechanical performance. Interfacial properties are often extracted via single-fiber composite tests. In these tests, the load is transferred from the polymer to the fiber through interfacial shear stresses, necessitating the evaluation of interfacial shear properties. To adopt these properties in the design of industrially relevant composites, one must assume that the damage mechanisms in single-fiber composites are representative of those in multi-fiber composites, consisting of highly aligned, unidirectional plies with high fiber volume fractions. That assumption, however, has never been validated. In this paper, the real-time damage development is monitored in single-fiber and multi-fiber composites using in situ X-ray holo-tomography at 150-nm pixel size. The technique enables the first-ever 3D detection of longitudinal interfacial debonding in carbon and glass single-fiber composites. This mechanism is not detected in multi-fiber composite specimens, suggesting that single-fiber composites are intrinsically unrepresentative of realistic composite behavior.

ZnO modified carbon fiber-matrix interfacial evaluation via nanoscale digital image correlation and nanoindentation

Improving the adherence of the fiber-matrix interface is an important step for enhancing the capabilities of polymer composites. In this study, carbon fibers were modified by growing zinc oxide (ZnO) nanorods on the fiber surface using a hydrothermal approach, with the aim of increasing the interfacial area and enhancing the friction between the fiber and the matrix. To fully understand the deformation mechanisms at the interface, a microscale evaluation combining nanoindentation with digital image correlation (DIC) for mapping the deformations by using nanoscale speckles is developed in this work. The main objective of this research was to develop a protocol for speckling the modified single fiber composite and show that DIC can be used in microscopic level and to evaluate the fiber-matrix interface by means of nano indentation. The speckle pattern was created using Ti nano powder and used to generate the strain maps in the fiber-matrix interface region. A comparative analysis of DIC results from ZnO modified carbon fibers has shown that shear strains around the interfacial boundary are 60 % reduced on average, as compared to neat carbon fibers, across all nano indentations from 8mN to 65mN of peak load. Results used direct strain measurements to confirm that modification by ZnO growth on the surface of individual fibers has a significant benefit to the interfacial mechanical properties of fiber-matrix composites.

Investigating the role of fibre-matrix interfacial degradation on the ageing process of carbon fibre-reinforced polymer under hydrothermal conditions

The aqueous environment can deteriorate the fibre-matrix interface of carbon fibre-reinforced polymer (CFRP), significantly impairing the non-fibre-dominated mechanical properties. Thus, this study aimed to quantitatively analyse the impact of interfacial degradation on the hydrothermal ageing mechanism and process of the CFRP. Firstly, entire water absorption process of the CFRP under hydrothermal conditions was divided into three stages according to experimental measurement of its water content. Based on this division of stages, a novel water diffusion model was established for the hydrothermally aged CFRP. To measure the mechanical degradation, tensile tests were conducted on unaged, aged, and redried neat epoxy and transversely positioned unidirectional (UD) CFRP specimens. It was found that the transverse tensile strength degradation of UD CFRP was irreversible due to the permanent interfacial debonding between the fibres and matrix, in contrast to the reversible ageing of the epoxy matrix. To further quantify the fibre-matrix interfacial ageing, physically-based models were established for the degraded interfacial strength of CFRP subjected to hydrothermal conditions. After the characterization of the modelling coefficients, the physically-based models can be employed to predict interfacial strength inside the aged CFRP for various ageing durations. The prediction error was only 4.57% for the transverse tensile strength of degraded UD CFRP with various ageing durations from the representative volume element (RVE) simulation with its interfacial strength provided by the physically-based models, validating the effectiveness of the proposed physically-based models for degraded fibre-matrix interface under various ageing conditions.

Numerical failure modelling of natural fibre composite coupons using X-ray computed tomography based modelling

Natural fibre composites offer versatile applications across industries while being superior in sustainability aspects compared to other composite types. To unlock their full potential, it is essential to understand their complex failure involving fibre failure, matrix cracking, and debonding at the fibre-matrix interface. Efforts to address these challenges focus on advanced numerical models, probing behaviour from micro to macro scales. However, these models face complexities in handling intricate failure modes given the non-uniform nature of natural fibres. To overcome these challenges, image-based modelling using X-ray computed tomography scans is proposed. This work’s novelty lies in integrating detailed microstructure information with a nonlinear calibration procedure to accurately model damage and failure in natural fiber composites. It marks a significant step toward developing a virtual testing model, paving the way for assessing composites with varying fiber content or fiber types.

Effect of laser ablation on mechanical performance of graphene-filled glass fibre reinforced polymer repaired composites

Abstract This paper aims to investigate the effect of laser ablation on the mechanical performance of graphene-filled glass fibre reinforced polymer (GFRP) repaired lap joints. The performance characteristics of repaired laminates were measured in terms of surface roughness, tensile strength and flexural strength according to ASTM standards. While the surface morphology was examined using a confocal microscope, scanning electron microscopy was adopted to analyse the laser ablated fibre–matrix interface. The average surface roughness significantly increased with an increase in laser power from 4 to 10 W which was attributed to the presence of graphene and burnt fibres. The laser ablation conditions corresponding to 10 W laser power, 300 mm s−1 scanning speed, 20 kHz of pulse frequency, 0.05 mm line spacing and 5 laser passes lead to the highest tensile strength (36.033 MPa) and bending strength (30.972 MPa) of GFRP laminates. The laser ablated microstructure was characterised by fibre pull-out, epoxy residue, burnt, clean fibres as evidenced by scanning electron microscopy.

The mechanical behavior and crack propagation mechanism evolution of heterogeneous C/HfC-SiC composites caused by extreme ablation environment exceeding 2300 °C

In this study, we conducted oxyacetylene ablation, followed by bending tests and comprehensive microstructural characterization, to investigate the mechanical behavior of C/HfC-SiC composites. The findings indicate a marked reduction in the flexural strength and fracture energy of ablated C/HfC-SiC composites, which decreased from 286.09 ± 17.56 MPa and 5.04 ± 0.27 mJ/mm2 to 190.97 ± 16.69 MPa and 3.80 ± 0.29 mJ/mm2, respectively. Notably, the fracture energy retention rate (75.40 %) of the composites exceeds the flexural strength retention rate (66.75 %). Based on the microstructure of cracks and energy release rate criterion, the failure process and crack propagation mechanism were analyzed. The ablation process was found to diminish the shear strength of the fiber-matrix interface, facilitating mechanical behaviors such as fiber debonding, slipping, and pull-out. Additionally, oxidative damage induces the simultaneous propagation of multiple cracks, thereby increasing energy consumption during the bending. These plastic mechanical behaviors not only increase the failure displacement but also enhance the plastic characteristics of the composites, allowing it to maintain higher flexural strength (from 69.3 MPa to 108.3 MPa) and fracture energy (from approximately 2.71 mJ/mm2 to 4.26 mJ/mm2) after failure (at the double failure displacement).

Electrical and dynamic mechanical analysis of kenaf fiber reinforced epoxy composites hybridized with acacia concinna powder

The objective of this work is to create and analyze composites made of kenaf fibers and epoxy polymer, which are strengthened by the addition of Acacia concinna pod (ACP) powder. These composites are intended for use in electrical insulation applications. The study investigated the impact of alkali treatment using a 6% NaOH solution on kenaf fiber. The effects were analyzed in relation to the dielectric and dynamic mechanical properties, while also considering the addition of different quantities of ACP powder (0%, 4%, and 8%). The composites were produced using the hand layup method, and the dielectric constant, dissipation factor, storage modulus, loss modulus, and damping factor were assessed. The study demonstrated that NaOH-treated kenaf fiber composites displayed considerably lower dielectric constant values than untreated composites, due to increased fiber crystallinity and decreased moisture absorption. Dynamic Mechanical Analysis (DMA) found that untreated composites had greater storage modulus and glass transition temperature (Tg) due to reduced segmental motion at the fiber-matrix interface. SEM research indicated better fiber-matrix bonding in treated composites, with decreased voids and robust interlocking, notably in those containing 4% Acacia concinna (ACP) filler. These findings show that NaOH treatment substantially enhances the performance of hybrid composites for electrical insulating applications.

Debonding Fiber Damage Mechanism Modeling for Machining Damage Inhibition During Rotary Ultrasonic Face Grinding SiO2f/SiO2

Abstract The debonding fiber defects on the grinding surface of SiO2f/SiO2 ceramic matrix composites deteriorate the service performance of related components. The low-damage process window is the key information to suppress machining damage by controlling grinding parameters. A mechanism model for debonding fiber damage on SiO2f/SiO2 surface was first proposed in this paper by the large deformation analysis for SiO2 fibers during rotary ultrasonic face grinding (RUFG). The established mechanism model built a bridge between grinding parameters and damage inhibition by integrating the ultrasonic stress effect, grinding force calculation, and critical fracture curvature cutting-off criterion of SiO2 fibers. The modeling mechanism for fiber deformation and fracture in grinding was validated by in situ observation of single abrasive grit scratching experiments. Besides, the low debonding damage process window predicted by the model was verified by experimental results and could be adopted to suppress the debonding fiber damage in grinding. The affected mechanism of fiber orientation, ultrasonic amplitude, and fiber-matrix interface strength on the low debonding damage process window was analyzed based on the theoretical and experimental results. The damage inhibition effect of the RUFG process was limited by the low fiber-matrix interface strength and axial cutter-relieving movement component. The ultrasonic-assisted vibration exerted its auxiliary effects through the ultrasonic stress effect and force reduction effect. The prerequisite for exerting the damage inhibition effect of RUFG was that the fiber-matrix interface strength was sufficient to resist the negative influence of the ultrasonic stress effect.

Simultaneous Measurement of Fiber-Matrix Interface Debonding and Tunneling Using a Dual-Vision Experimental Setup

BackgroundFiber-matrix debonding is a precursor for transverse cracking and several other types of damage in fiber composites. However, to date, there are limited experiment-based reports that study the fundamental mechanisms of fiber-matrix debonding.ObjectiveThis work aims to uncover the governing mechanisms of fiber-matrix interface debonding by full-field measurements supplemented by numerical simulations. In particular, the application of a dual-vision image-based characterization approach on single glass macro fiber samples is discussed and proven useful in understanding the in-plane and out-of-plane debonding characteristics at the fiber-matrix interface.MethodsFull-field strain and displacement measurements based on digital image correlation are performed on model single-fiber composites. The use of a dual-vision system allows strain measurements in the vicinity of the fiber-matrix interface, also allowing for the identification of critical strain and stress values corresponding to the initiation and propagation of debonding damage. The experimental data are used to calibrate an inverse identification approach that outputs the shape of the debonded interface along the fiber length.ResultsFull-field measurements allow for establishing correlations between local and global strain fields. Observation of debonding propagation along the fiber axis seems to be representative of the crack tunneling during the early stages of the failure process, i.e., when the crack tip is subjected to opening mode only.ConclusionsSide view measurements are useful as a first-order approximation of the debonding propagation velocity along the fiber axis but fail to provide accurate measurements for the debonding shape, esp. in areas where the crack is under a dominantly shear stress state. This issue can be resolved by full-field measurements coupled with computational simulations.

Experimental study on the effects of temperature on mechanical properties of 3D printed continuous carbon fiber reinforced polymer (C[sbnd]CFRP) composites

Design for safety of 3D printed continuous carbon fiber reinforced polymer (CCFRP) composites remains challenging for accommodating harsh service environments with a wide range of temperatures. To investigate thermal effects on mechanical properties and failure mechanism of CCFRP materials, this study carried out a series of experimental tests on the laminates with layups of [0]n, [90]n and [0/90]n for tension, as well as [±45]n for in-plane shearing. The application of classical laminate theory and rule of mixtures to the 3D printed CCFRP composites under varying temperatures is then evaluated. The results indicate that the transverse elastic modulus/strength and in-plane shear modulus/strength increase at a low temperature, but all the mechanical properties decrease at a high temperature. Notably, an unexpected decrease in strength of [0/90]n laminates is observed when the temperature drops from −10 °C to −40 °C. Significant strain concentrations are visualized during tensile experiments at high temperature through the digital image correlation (DIC) technique. With increasing temperature, the [0]n laminates undergo a transition from an explosive to a jagged failure mode, while the [90]n laminates shift from brittle to ductile failure. The alteration is attributed to decrease in the mechanical properties of both the matrix and the matrix fiber interface, as revealed by scanning electron microscopy (SEM) analysis. It is found that although the classical laminate theory exhibits an acceptable prediction accuracy for the 3D printed CCFRP composites under varying temperature conditions, the rule of mixtures is not applicable. For this reason, the new formulations for the rule of mixtures are then proposed to enable accurate predictions for 3D printed CCFRP composites under different temperatures. This study is anticipated to provide insightful understanding on mechanical properties and failure mechanisms for 3D printed CCFRP composites at different temperatures.

Effect of curing regimes on mechanical properties and microstructure of engineered cementitious composites with full desert sand

To establish a curing regime that facilitates the rapid enhancement and stable progression of early-age strength and tensile ductility in engineered cementitious composites with full desert sand (DSECC), aligning with production efficiency, this study examines the effects of different curing regimes (standard curing, natural curing, 20℃ water curing, and 90℃ water bath curing) on DSECC 's the mechanical properties and microstructure. The findings indicate that 90℃ water bath curing is beneficial to enhance the mechanical properties of DSECC, and its early 7 days strength and tensile deformation capacity (up to 7.05 %) can reach or exceed the standard curing 28 days level. In the uniaxial tensile test, samples cured in 20℃ water exhibit increased crack widths and reduced crack numbers, resulting in a sharp decline in the ultimate tensile strain from 4.96 % at 14 days to 1.57 % at 28 days. Natural curing leads to regression in strength at 28 days. The microstructure analysis revealed that 90℃ water bath curing fostered the development of high-density C-S-H gel and the dissolution of desert sand, while preserving the integrity of the fibers, enhancing the fiber-matrix interface transition zone (ITZ). The pore characteristic parameters under 90℃ water bath curing are superior, which has a notable refinement of the DSECC matrix's pore size. 20℃ Water curing can make up for the defects caused by desert sand and improve the compactness of matrix-aggregate ITZ. Natural curing yields the lowest degree of matrix hydration, with porosity reaching as high as 41.90 %, and pores smaller than 50 nm accounting for only 8.97 %.

Hybrid Fiber Reinforced Lightweight Concrete: Vegetal and Metalized Plastic Waste Fiber Synergy and Pull-Out Behavior

Abstract Using one or more fibers in concrete is called “hybridization.” Although single-fiber concrete offers excellent performance, concrete reinforced with hybrid fibers gains speed as the synergy between the fibers results in amplified performance. This experimental work reflects the effects of incorporating 1, 2, and 3 % untreated singular and hybrid fibers on the physical and mechanical properties of lightweight concrete (LC) at 3, 28, and 90 days. Six mixture types were used: control LC, LC containing metalized plastic waste fibers (MPWFs), LC containing date palm fibers (DPFs), LC containing sisal fibers (SFs), LC with MPWFs and DPFs (Hybrid A), and LC with MPWFs and SFs (Hybrid B). In the fresh state, fiber introduction affected all mixes’ workability and wet density, and the reduction in slump and wet density was proportional to the fiber dose. However, in the hardened state, the results indicate that compressive strength (CS) and modulus of elasticity (MOE) decreased for LC containing only plastic or SFs. However, these properties increased slightly over the long term for blends containing 1 % DPF. Excepting mixtures containing MPWFs, fiber introduction improved flexural strength (FS) for all blends containing 1 % and 2 % fibers at 28 and 90 days. The most significant gains in FS were 8 % and 4 % at 28 and 90 days, respectively, for samples containing 1 % DPF. Nevertheless, fiber hybridization improved these mechanical properties and created a positive synergy in long-term bending. At 1 % fiber dosage, CS, MOE, and FS increased respectively by 3.05, 3.10, and 8 % for Hybrid A compared with the control LC. Pull-out testing provides the best means to understand typical failure modes and assess maximum tensile strength. Consequently, microstructural analysis enabled us to examine the bonding quality at the fiber-matrix interface.

Investigation of non-uniform carbonation in strain-hardening magnesia composite (SHMC) and its impacts on fiber-matrix interface and fiber-bridging properties

Unlike Portland cement, the reactive magnesia cement (RMC) develops its strength via carbonation. Non-uniform microstructure and properties due to the varied carbonation degree across cross-section depth have thus been observed. However, the existing micromechanics design theory employs uniform material properties (cementitious matrix and fiber-matrix interface characteristics) to design strain-hardening composites. This research investigated such non-uniform carbonation in a strain-hardening magnesia composite (SHMC) and its impacts on fiber-matrix interface and fiber-bridging properties. Results showed that mineral phase composition (of the cementitious matrix) and fiber-matrix interface properties across cross-section depth are highly non-uniform in SHMC due to varied carbonation degrees. The outer layer exhibited a much higher carbonation degree with significantly stronger fiber-matrix friction, while the inner core showed negligible carbonation with distinct fiber-matrix properties. Insights gained from the micro-scale investigation were used to calculate the fiber-bridging constitutive law of SHMC with non-uniform carbonation across cross-section depth and to assess its strain-hardening performance. This investigation highlights the importance and necessity of considering non-uniform carbonation in the modeling and design of SHMC. The study presents a framework for the consideration of non-uniform micromechanical parameters in the design of strain-hardening cementitious composites.

Mechanical properties of sisal fiber-reinforced fly ash cement mortar activated by sodium sulfate

The substantial use of fly ash as cement replacement to reduce carbon emissions is identified as the primary goal, 50 % of the cement was substituted with fly ash and in order to avoid the low early stage mechanical properties of the composite, varying doses of sodium sulfate were used as an activator of fly ash. Additionally, sisal fibers were chosen to enhance the flexural strength. The results indicate that sodium sulfate significantly enhances the early stage mechanical performance of the cementitious composites and the matrix exhibits the optimal mechanical performance at 4 wt% sodium sulfate dosage (4SS). The addition of sisal fibers resulted in an enhancement of the flexural performance of the material. The collaboration between sodium sulfate and sisal fibers results in an improvement in the initial flexural performance of the material while preserving its compressive strength. The single-fiber pullout test further confirmed that adding sodium sulfate enhances the fiber-matrix interface and bonding. Microstructural investigations by XRD, TGA, MIP, and SEM-EDS revealed accelerated hydration and early formation of a large amount of ettringite due to the addition of sodium sulfate. Ettringite acts as a gel nucleation seed, promoting the formation of a dense gel structure and effectively improving the early mechanical properties of the composite. Furthermore, with curing age, sodium sulfate also effectively improves the pore structure of the matrix in the late hydration stage.

Effects of temperature on the anisotropic mechanical properties and failure mechanisms of Sheet Molding Compounds

Sheet Molding Compounds (SMC) are widely used in many industries. Due to their high in-mold flow, fibers tend to align during the component processing and generate anisotropic mechanical properties. Besides, being SMCs thermoset composites, their application in high temperature environments often results to be of interest. In this research, the fiber orientation and temperature-dependent mechanical behavior and failure mechanisms were studied. First, materials were compression molded into plates, promoting fiber orientation. Then, the materials’ orientation-dependent viscoelastic behavior was analyzed by Dynamic Mechanical Analysis, and their anisotropy level was assessed at quasi-static tensile, bending and compression modes at 23 °C and 130 °C. Finally, the failure mechanisms were inspected by confocal microscopy to evaluate the influence of temperature and fiber orientation on them. The results demonstrate how the temperature influences the material’s mechanical performance and their anisotropic behavior, especially at 45°. Likewise, temperature alters failure mechanisms, by triggering the fiber-matrix interface failure.

New interpretation model of the effect of short PE fibers in TRM on tensile behavior

An experimental investigation was conducted on the tensile behavior of textile reinforced mortar (TRM) composites containing different volumes of short polyethylene (PE) fibers in a cementitious matrix to improve the tensile strength and cracking mode of TRM. This investigation mainly aimed to study the action mechanism of short fibers and propose a reasonable textile-short fiber-matrix interface model. The short fiber content was varied, as was the matrix type and the number of grid layers. Ten groups of TRM tensile specimens subjected to the monotonic uniaxial tensile loading were fabricated and tested to examine their tensile characteristics. The results showed that the multiple-cracking behavior and failure mode of TRM were significantly improved by adding PE fibers into the matrix. The tensile strength was increased by 25.8–167.2 %. After the uniaxial tensile tests, the microscopic investigation of the interface between the textile and matrix was conducted on the tensile specimens using an environmental scanning electron microscope (ESEM). The significant influence of the short PE fibers on the improvement of the interface bonding between the textile and matrix was confirmed. More importantly, based on the ESEM results, a novel interface model was proposed to promote understanding of the action mechanism of short fibers.