Residual Strain Research Articles

Study of freeze-thaw deterioration of saturated and unsaturated hydraulic concrete based on measured strain

In actual concrete water projects, areas such as the back surface, above-water surface, and even areas where the water level fluctuates are in the unsaturated freeze-thaw state. The complexity of freeze-thaw tests of unsaturated hydraulic concrete has thus far prevented a sound understanding of the mechanisms at work in freeze-thaw deterioration of unsaturated hydraulic concrete. Given this situation, this study first compares three different unsaturated hydraulic concrete freeze-thaw test processes (polyurea seal, paraffin seal, and vacuum-bag seal) and then uses the vacuum-bag seal method to implement freeze-thaw tests of unsaturated hydraulic concrete. Afterward, three test schemes (unsaturated sealed freeze-thaw, water-freeze-thaw without air-entraining agent, and water-freeze-thaw with air-entraining agents) are conducted and the mechanisms of freeze-thaw deterioration of saturated and unsaturated hydraulic concrete are evaluated based on the measured temperature and strain of the concrete specimens. The results reveal a continuous and irreversible deterioration leading to the freeze-thaw damage of unsaturated sealed freeze-thaw specimens and water-freeze-thaw specimens with and without an air-entraining agent. After 200 freeze-thaw cycles, the cumulative residual strain of the aforementioned three test schemes reach 47 με, 616 με, and 273 με, respectively. The thermal expansion coefficient of concrete remains relatively constant with increasing freeze-thaw cycles. Water-freeze-thaw specimens without air-entraining agents have a greater thermal expansion coefficient than those with air-entraining agents, and unsaturated sealed freeze-thaw specimens have the smallest thermal expansion coefficient. The frost heave coefficient increases with increasing freeze-thaw cycles, and water-freeze-thaw specimens without air-entraining agents have greater frost heave coefficients than those with air-entraining agents.

Effect of cold work level on the crack propagation behaviour of 316LN stainless steel in high-temperature pressurized water

We investigated the microstructure, mechanical properties, and stress corrosion cracking (SCC) propagation behaviour of 316LN austenitic stainless steel with various cold work (CW) levels. CW increased the crack growth rate of 316LN. The stress corrosion crack growth rate (SCCGR) for 316LN with 5% CW was approximately 6.52% higher than that of the solution-annealed state; 10%, 20%, and 30% CW resulted in 1.20, 3.18, and 6.10 times higher SCCGRs, respectively. A larger residual strain and proliferation of slip bands via cold deformation augmented the SCCGR. The SCC propagation mechanism of 316LN changed with increasing CW levels owing to slip bands.

Toward sustainable manufacturing of highly efficient and stable semi-transparent perovskite solar cells: The critical role of green solvent properties

Perovskite solar cells, promising a bright future in the energy market, are now being prioritized for high-throughput production to match their remarkable success at the laboratory scale. However, the use of toxic solvents proved to be one of the major constraints on scaling up production. Herein, a green solvent system consist of dimethyl sulfoxide (DMSO) and 1-dodecyl-3-methylimidazolium chloride ([C12MIM]Cl) ionic liquids (ILs) was developed to modulate the crystallization of wide-bandgap (WBG) perovskite films combined with a antisolvent-free process, i.e., nitrogen (N2) quenching method. The [C12MIM]Cl IL promoted the crystallization of WBG perovskite films with large grain sizes, reduced photo-active PbI2, modulated residual strain, prolonged carrier lifetimes as well as improved energy alignment. Consequently, the [C12MIM]Cl-modified single-junction 1.77 eV perovskite solar cells (PSCs) achieved a champion efficiency of 18.75 % with an excellent operational stability, retaining an initial PCE of 93 % after 2000 h of maximum-power-point tacking test. Meanwhile, the positive effect of the [C12MIM]Cl ILs was universal in perovskite with different bandgaps at 1.53, 1.68 and 1.72 eV, respectively. Furthermore, stacking semi-transparent [C12MIM]Cl-modified 1.77 eV WBG PSCs as top cells coupled with 1.27 eV OPV or 1.24 eV Sn-Pb PSC as bottom cells for the 4 T tandem configuration showed impressive PCE of 26.01 % and 27.44 %, respectively. This study opens a new avenue toward the sustainable fabrication of highly efficient and stable perovskite-based semitransparent and tandem solar cells.

Nano-micrometer scale characterization of PWSCC crack tips in the transition zone of 52M overlay and the implication to intergranular cracking

This study examines the microstructural characteristics of the primary water stress corrosion cracking (PWSCC) crack tip in the transition zone (TZ) of the 52 M overlay and its implications for intergranular cracking. In the TZ, the Cr content at grain boundaries near the fusion boundary (FB) is lower than those farther from the FB. Additionally, residual strain at grain boundaries near the FB is higher than that farther away, with the fine-grained zone around the FB showing higher local deformation than the surrounding columnar grains. Stress corrosion cracking (SCC) crack growth rate (CGR) test results indicate that the TZ showed certain SCC sensitivity, and the closer to the FB, the lower the SCC resistance. Analysis of the SCC crack tip found that the distinctive composition distribution of the 52 M overlay TZ, characterized by low Cr and high Fe near the FB, is prone to intergranular oxidation, thereby reducing SCC resistance. Conversely, higher Cr and lower Fe content at grain boundaries in the TZ farther from the FB form dense, Cr-rich oxides ahead of the crack tip that slow SCC crack growth, resulting in the diffusion of oxidation along the dislocation structure into the grains and forming a fibrous oxidation zone.

Effect of fast frequency double pulse current on microstructural characteristics and mechanical properties of wire arc additively manufactured Ti-6Al-4V alloy

This study introduces an innovative technique known as fast-frequency double pulse wire arc metal additive manufacturing (FFDP-WAAM). This method employs periodic fluctuations in arc plasma and force to enhance the stirring effect within the molten pool, resulting in the fragmentation of β grains and the formation of finer prior-β grains. The microstructure primarily comprises α', attributed to the high cooling rates and minimal heat accumulation. Compared to the conventional gas tungsten arc welding-based WAAM (CGT-WAAM) process, FFDP-WAAM significantly reduces α-variant selection, thereby achieving a more uniform α phase orientation distribution. Additionally, ultrasonic vibration in the FFDP-WAAM process facilitates recrystallization and mitigates residual strain. The tensile strength and elongation of the FFDP-WAAM specimens reached 939.2 MPa and 9.0 %, respectively, whereas the CGT-WAAM specimens showed a lower tensile strength of 830 MPa and elongation of 9.2 %. The enhanced strength, fatigue life and microhardness of Ti-6Al-4V produced by FFDP-WAAM is ascribed to the refined grain-size distribution. Furthermore, the low Schmid factor (SF) distribution and the stable triangular structure of Category I α-clusters are anticipated to contribute to the increased strength of the FFDP-WAAM-fabricated wall.

Investigating microstructure dynamics and strain rate sensitivity in gradient nanostructured AISI 304 L stainless steel: TEM and nanoindentation insights

In recent years, gradient nanostructured (GNS) materials have gained significant attention due to their superior strength-ductility balance and enhanced functional properties compared to their coarse-grained counterparts. This research examines the microstructure evolution and nanomechanical responses of GNS AISI 304 L austenitic stainless steel using transmission electron microscopy (TEM) and nanoindentation techniques. Through surface mechanical attrition treatment (SMAT), a gradient nanostructured layer with ultrafine grains (∼15 nm) and nanoscale martensite (up to ∼40 %) within the austenite matrix has been successfully created on the steel’s surface. This treated surface exhibits a hardness of ∼6.7 GPa, nearly double the original value. The GNS layer demonstrates single-step (γ → α’) and two-step (γ → ε → α’) martensitic transformations, deformation twinning (γ -twin), a decrease in the density of deformation bands, compressive residual stress, lattice strain, and martensite content, along with an increase in grain size. Strain rate sensitivity (SRS) increases with austenitic grain size and inversely correlates with martensite proportion as depth increases in the GNS layer. A significant amount of ultrafine martensite is primarily responsible for the limited SRS in the topmost layer.

Mapping Spatial Strain Distribution and Its Effects on Optoelectronic Properties in Wrinkled Perovskite Films.

Organic-inorganic halide perovskite films, fabricated by using the antisolvent method, have garnered intense attention for their application in high-efficiency and stable solar cells. These films characteristically develop periodic wrinkled microstructures. Previous research has indicated that macroscopic residual strain significantly influences the optoelectronic behaviors of these films. However, the detailed interplay between the wrinkled morphology, strain distribution, and local photophysical properties at the micro- and nanoscale has not been fully elucidated. Here, we explore the microscopic morphology-strain-property relationship within wrinkled perovskite films employing correlative micro-optical and nanoelectrical microscopy techniques. Microphotoluminescence (PL) mapping supplemented by in situ strain PL measurements identifies a heterogeneous spatial strain distribution across the microstructural hills and valleys. Additionally, light-intensity-dependent photoconductive atomic force microscopy reveals that valleys experiencing less compressive strain exhibit a lower conductivity and a higher propensity for ion migration. The findings underscore the potential of targeted strain engineering to optimize the performance and longevity of perovskite solar cells.

Rational Tailored Polyfluorosubstituted Amide Molecule for Stabilizing PbI6 Framework and Inhibiting Ion Migration Toward Highly Efficient and Stable Perovskite Solar Cells

AbstractPerovskite solar cells (PSCs), while highly efficient, face stability challenges that hinder their commercial application. These instability issues mainly arise from the fragile nature of Pb─I bonds in perovskites, which easily break under environmental stresses such as heat and light, leading to the breakdown of the [PbI6] framework and irreversible degradation. To address these issues, a multifunctional molecule, N1,N4‐bis(2,3,5,6‐tetrafluoro‐4‐iodophenyl)terephthalamide (FIPh‐A), is designed and synthesized to enhance the stability of perovskite films and devices. FIPh‐A molecule possesses carbonyl, amino, and iodotetrafluorophenyl groups that bind and stabilize Pb2+ ions and [PbI6]4− octahedra structure, preventing ion migration in perovskite films. The activation energy of ion migration increases obviously from 0.28 eV to 0.39 eV by adding FIPh‐A verified by experiment results. The residual strain is also released efficiently by introducing FIPh‐A molecule into perovskite films characterized by grazing incidence X‐ray diffraction. The champion PSC with FIPh‐A achieves a power conversion efficiency of 24.60%. After 500 h of continuous illumination (ISOS‐L‐1) and 300 h of thermal aging at 80 °C (ISOS‐D‐2I), these PSCs with FIPh‐A maintained 93% and 77% of their initial efficiency, respectively. These results emphasize the potential of multifunctional additives in overcoming the stability challenges of PSCs, thereby facilitating their commercial advancement.

Mechanical properties and multi-field ferroelastic response of Nb/Mn Co-doped CaBi4Ti4O15 high-temperature ferroelectric ceramics

CaBi4Ti4O15 (CBT) ceramics are promising piezoelectric materials that have been widely studied for high-temperature applications. Despite significant advancements in the electrical performance of CBT ceramics, the understanding of their mechanical behaviors remains limited, which is unfavorable for designing ceramics with high stability and reliability during high-temperature service. This work investigated the mechanical properties and fracture behaviors of Nb/Mn co-doped CaBi4Ti4O15 (CBTNM) with various doping levels, focusing on stress-strain responses and ferroelastic deformation behaviors under uniaxial compression and multi-field coupling conditions. HRTEM analysis reveals small-scale layered domain wall structures on the surface of plate-like grains. The fracture and compressive strengths of CBTNM ceramics initially decrease and then increase with an increase in doping content, and the underlying mechanisms are related to grain size, defects, and densification. CBTNM ceramics exhibit nonlinear stress-strain responses due to ferroelastic deformation under compressive loading, and the resultant irreversible domain switching strain increases with an increase in doping content, while poling can further increase the residual strain. Under multi-field loading conditions, CBTNM ceramics undergo more ferroelastic deformation events and exhibit larger residual strain. The micro-cracks, pores, complicated fracture modes, and degraded fracture surfaces with fragmental and rough features are mainly responsible for the lower elastic modulus and inferior mechanical response. This work enhances our understanding of the mechanical behaviors of high-temperature piezoelectric ceramics and provides guidance for designing high-performance piezoelectric materials for complex environmental applications.

Multifunctional molecular bridge enabled interface passivation and strain release for stable and efficient all-inorganic perovskite solar cells

The precise management of the buried interface in n-i-p perovskite solar cells (PSCs) to achieve efficient charge extraction and transport is crucial for improving the photovoltaic performance. Here, a 4-chloro-2,5-dimethoxyaniline (CDA) modifier with multifunctional groups is utilized as a molecular bridge at the TiO2/CsPbBr3 buried interface to enhance the qualities of TiO2 and CsPbBr3 films and the arrangement of interface energy level. The chlorine atom in CDA can heal the oxygen vacancies defects on the TiO2 film surface, thereby improving its electron mobility and conductivity. The –O– and -NH2 groups in CDA play a passivation effect on the ions defects of CsPbBr3 film, and especially the two –O– groups can anchor the lattice Pb atoms of CsPbBr3 perovskite, which effectively reduce the trap states of CsPbBr3 film and release the residual lattice strain. The modification of CDA also improves the wettability and energy level of TiO2 film to optimize CsPbBr3 crystal growth and charge transport, respectively. Consequently, the CsPbBr3 PSCs with CDA molecular bridge free of encapsulation achieve a highly increased power conversion efficiency of 10.85%, in contrast with 8.16% value of the control device. After 720 h of storage at 85 °C and in air environment with 85% relative humidity, the efficiency of the CDA-modified device retains 93.1% of the initial value, demonstrating excellent long-term humidity and thermal stability.

Development of sandwich test coupons with continuous protective layers for accurate determination of the tensile failure strain of unidirectional carbon fibre reinforced composites

Recently introduced unidirectional (UD) carbon fibre reinforced epoxy (CF/EP) tensile test coupons with continuous protective layers were developed further by comparing three coupon designs with different layer integration techniques. Consistent experimental data was generated with high sample number and low scatter. Thermal residual strains were considered in case of two coupon designs where the layers were integrated at elevated temperature. A curve-fitting-based strength evaluation method is proposed for the sandwich coupons since this parameter cannot be evaluated directly. The sandwich type coupons yielded statistically significant increase in their average failure strain compared to that of the baseline tabbed coupons. In contrast, the three sandwich coupon types did not show significant differences. Therefore, the sandwich coupon type made by bonding cured UD composite layers together at room temperature is proposed for further application as they allow for full delamination at CF/EP layer fracture and do not require thermal strain correction during the evaluation.

Synthesis of Multifunctional Organic Molecules via Michael Addition Reaction to Manage Perovskite Crystallization and Defect.

Additive engineering plays a pivotal role in achieving high-quality light-absorbing layers for high-performance and stable perovskite solar cells (PSCs). Various functional groups within the additives exert distinct regulatory effects on the perovskite layer. However, few additive molecules can synergistically fulfill the dual functions of regulating crystallization and passivating defects. Here, we custom-synthesized 2-ureido-4-pyrimidone (UPy) organic small molecules with diverse functional groups as additives to modulate crystallization and defects in perovskite films via the Michael addition reaction. Theoretical and experimental investigations demonstrate that the -OH groups in UPy exhibit significant effects in fixing uncoordinated Pb2+ ions, passivation of lead-iodide antisite defects, alleviating hysteresis, and reducing non-radiative recombination. Furthermore, the enhanced C=O and -NH2 motifs interact with the A-site cation via hydrogen bonding, which relieves residual strain and adjusts crystal orientation. This strategy effectively controls perovskite crystallization and passivates defects, ultimately enhancing the quality of perovskite films. Consequently, the open-circuit voltage of the UPy-based p-i-n PSCs reaches 1.20 V, and the fill factor surpasses 84%. The champion device delivers a power conversion efficiency of 25.75%. Remarkably, the unencapsulated device maintained 96.9% and 94.5% of its initial efficiency following 3,360 hours of dark storage and 1,866 hours of 1-sun illumination, respectively.

Interfacial crosslinking benzimidazolium enables eco-friendly inverted perovskite solar cells and modules

Interfacial engineering via controlled crosslinking at perovskite surface is of significance to address the interfacial loss in inverted perovskite solar cells (PSCs), while is unfortunately impeded by the unsatisfied interfacial charge extraction and transfer owing to the inherent low conductivity of the formed crosslinked network. We herein propose and validate a strategy of interfacial crosslinking benzimidazolium (ICB) that is capable of reducing the surface residual strain of perovskite and improving the interfacial carrier transfer, leading to a new benchmark of power conversion efficiency (PCE) up to 25.30 % in inverted PSCs, as well as 21.73 % in inverted PSC modules (6 × 6 cm²). Such the ICB network also results in sustainable PSCs and modules with superior stability even under various harsh conditions, e.g. suppressing lead leakage of PSCs with the rate of 83.6 %, maintaining the initial efficiency of 90 % after 1200 h of continuous heating at 85 °C, and 92.8 % of its pristine efficiency over 1200 h of continuous irradiation. We thus believe that present work demonstrates the potential of ionic molecules crosslinking at interfaces for high performance inverted PSCs.

The defects and compressive behavior of NiTi alloy fabricated by laser powder bed fusion under a wide process space

A wide process space with laser power (P) of 50 ～ 400 W and scanning speed (s) of 50 ～ 2400 mm/s with the energy density (ED) range of 93–556 J/mm3 has been employed to fabricate NiTi alloy using laser powder bed fusion (LPBF). The optimal process window for near-full dense materials free of geometrical and metallurgical defects was determined. The characteristics of microstructures and compressive behaviors were comprehensively investigated. The results have shown that the process combinations of “high P + low s” and “high P + high s” are prone to bulging and warping defects due to rapid heating and cooling, respectively. A combination of “low P + low s” produces a relatively shallow melt pool without keyhole formation even at ED as high as 556 J/mm3. The austenite-martensite phase transition temperature (TTs) variations of ～80℃ were obtained with the process window free of porosity. The pre-existing martensite lath probably formed by plastic distortion (bulging) was responsible for the lowest critical stress of induced martensite (σSIM). The texture and nano-sized NiTi2/Ni2Ti4Ox precipitates also contribute to the variation of σSIM and residual strain among the samples with the same level of TTs upon compressive loading.

Damage indicators in unidirectional natural fibre composites under fatigue loading

This paper investigates the occurrence of failure under fatigue loading of unidirectional flax fibre composites with different matrices. Various parameters, such as dissipated energy, residual strain, and stiffness, were measured to evaluate fatigue damage and the fatigue life of composites. The results indicate that absolute dissipated energy may not be the most suitable indicator for assessing damage in natural fibre composites when they are subjected to fatigue before reaching failure. The research proposes to rather consider the “loss factor”, defined as the ratio of dissipated energy to total energy stored in each cycle. This indicator appears to provide a more effective means of evaluating fatigue life of the studied composites, especially when compared to the dissipated energy observed during fatigue tests at low stress levels. Fatigue and acoustic emission results indicate that biocomposites with better fibre–matrix adhesion show a delayed damage initiation and propagation, as well as longer fatigue life.

Fatigue performance and damage of partially prestressed concrete beam with fiber reinforcement

Ordinary concrete exhibits low strength and a propensity for cracking. Carbon fibers and aramid fibers, as materials characterized by high strength, high toughness, and excellent fatigue resistance, can effectively limit the propagation of micro-cracks and enhance the strength of concrete. To explore the influence of different fiber types on the fatigue performance of prestressed concrete beams, this study initiates from the perspective of beam components. Employing a combination of experimental research and theoretical analysis, it conducts bending and constant-amplitude fatigue tests on 12 prestressed concrete beams with various fiber types. Based on the stiffness of the beam section and residual strain, the damage evolution patterns of the tested beams were described. The results indicated that the utilization of fiber-reinforced concrete significantly improves the fatigue life and residual bearing capacity of the beam components. Specifically, the residual bearing capacities of beams reinforced with carbon fibers, aramid fibers, and hybrid fibers increased by 58.6 %, 49.5 %, and 64.9 %, respectively. The analysis revealed that residual strain is a suitable indicator for describing fatigue damage in specimens and recommends prioritizing the concrete residual strain index. These findings provided a theoretical basis for the application of fiber-reinforced concrete in practical engineering projects and lifespan assessment.

StrainNet-LD: Large Displacement digital image correlation based on deep learning and displacement-field decomposition

First, a displacement-field decomposition strategy is proposed that effectively enhances the accuracy of digital image correlation (DIC) algorithms under large displacement or deformation conditions. The implementation methodologies of displacement-field decomposition under both Lagrangian and Eulerian descriptions are derived and presented. Second, displacement-field decomposition is applied to speckle image correlation algorithms based on deep learning, resolving the contradiction between registration capability of large displacement and the accuracy. A CUDA-accelerated and residual learning-based strain fitting algorithm is proposed for high-precision and real-time strain computation. This method is named “StrainNet for Large Displacement” (StrainNet-LD). StrainNet-LD achieves a calculation speed of 768 × 768 × 6 fps (768 × 768 × 3 fps with strain calculated simultaneously) on GPU with displacement MAE < 0.05 pixels and strain MAE < 0.002ε. Finally, rubber tensile tests, 3D motion measurement of composite shells, and morphology reconstruction experiments of speckle-free composite repair structures are conducted to validate the algorithm's robustness and efficiency. Some vital discussions of displacement-field decomposition are given in the Appendixes. The code and dataset are available at https://github.com/GW-Wang-thu/StrainNet-LD.

Residual Strain and Joint Pressurization Maintain Collagen Tension for On-Joint Lumbar Facet Capsular Ligaments.

Modeling the lumbar facet capsular ligament's (FCL) mechanical behavior under various physiological motions has often been a challenge due to limited knowledge about the on-joint in situ ligament state arising from attachment to the bone or other internal loads. Building on prior work, this study presents an enhanced computational model of the lumbar facet capsular ligament by incorporating residual strain and joint pressurization strain, factors neglected in prior models. Further, the model can predict strain and stress distribution across the ligament under various spinal motions, highlighting the influence of the ligament's attachment to the bone, internal synovial fluid pressurization, and distribution of collagen fiber alignment on the overall mechanical response of the ligament. Joint space inflation was found to influence the total observed stress and strain fields, both at rest and during motion. A significant portion of the ligament was found to be in tension, even in the absence of external load. Additionally, the model's ability to account for residual strain offers a more realistic portrayal of the collagen fibers and elastin matrix's role in ligament mechanics. We conclude that (1) computational models of the lumbar facet capsular ligament should not assume that the ligament is unloaded when the joint is in its neutral position, and (2) the ligament is nearly always in tension, which may be important in terms of its long-term growth and remodeling.

Mechanical properties and ductility improvement mechanisms of fiber-reinforced biomimetic mineralized composites using sea sand

Biomimetic mineralized composites (BMC) is an emerging green cementing material. However, the application of BMC is limited by brittle failure. This study proposes novel fiber-reinforced biomimetic mineralized composites (FRBMC) with excellent ductility based on the coupling method of fiber reinforcement and biomimetic chemically induced calcium carbonate precipitation (BCICP). Three typical fibers, including polymer fibers (polypropylene fiber, PF), mineral fibers (basalt fiber, BF), and plant fibers (coir fiber, CF), were used to explore the feasibility of application in FRBMC. Accordingly, mechanical properties, pore structures, and microscopic characteristics were assessed through unconfined compressive strength (UCS) test, mercury intrusion porosimetry (MIP) tests, and scanning electron microscopy (SEM). The results show that fiber induces a transition from brittle to ductile failure modes in BMC. PF exhibits the most notable enhancement in residual strength and peak strain, while BF leads to the highest compressive strength. CF can effectively enhance energy absorption after reaching peak stress. Moreover, FRBMC with CF contains a higher quantity of minute pores, while BF can reduce the porosity of FRBMC. The calcium carbonate crystals effectively cement fibers and sand particles, enhancing the ductility of FRBMC through forming various cementing structures. This study investigates the synergistic effect of BCICP and fiber reinforcement, providing valuable guidance for potential practical applications of FRBMC.

Sensor-Enhanced Thick Laminated Composite Beams: Manufacturing, Testing, and Numerical Analysis.

This study investigates the manufacturing, testing, and analysis of ultra-thick laminated polymer matrix composite (PMC) beams with the aim of developing high-performance PMC leaf springs for automotive applications. An innovative aspect of this study is the integration of Fiber Bragg Grating (FBG) sensors and thermocouples (TCs) to monitor residual strain and exothermic reactions in composite structures during curing and post-curing manufacturing cycles. Additionally, the Calibration Coefficients (CCs) are calculated using Strain Gauge measurement results under static three-point bending tests. A major part of the study focuses on developing a properly correlated Finite Element (FE) model with large deflection (LD) effects using geometrical nonlinear analysis (GNA) to understand the deformation behavior of ultra thick composite beam (ComBeam) samples, advancing the understanding of large deformation behavior and filling critical research gaps in composite materials. This model will help assess the internal strain distribution, which is verified by correlating data from FBG sensors, Strain Gauges (SGs), and FE analysis. In addition, this research focuses on the application of FBG sensors in structural health monitoring (SHM) in fatigue tests under three-point bending with the support of load-deflection sensors: a new approach for composites at this scale. This study revealed that the fatigue performance of ComBeam samples drastically decreased with increasing displacement ranges, even at the same maximum level, underscoring the potential of FBG sensors to enhance SHM capabilities linked to smart maintenance.