Microcrack Density Research Articles

Statistical analysis of thermally induced pre-existing microcracks and their influence on fracture behaviours of granite rock

Rocks containing varying degrees of microcracks have a significant influence on their mechanical behavior. Understanding the effect of pre-existing microcracks (PEMs) on rock fracture mechanisms has scientific and practical value in areas such as geothermal energy, nuclear waste disposal and deep mining. We employed a thermally induced approach to create PEMs in granite rock, and quantified characteristic parameters of PEMs by visualization methods, focusing on the quantitative relationships between the PEMs and the mechanical strength and acoustic emission (AE) properties of the rock. We find that the distribution characteristics of thermally induced PEMs obey a lognormal distribution, and the length of individual thermally induced PEMs is almost independent of temperature. The density and orientation of PEMs together determine the variation of the longitudinal wave velocity and rock strength, with the effect of microcrack density dominating. The AE signal suggests that PEMs can affect the fracture behavior and fracture mechanism, depending on the relative dominance of pre-existing and stress-induced microcracks. The AF-RA values show that PEMs lead to an important shift in the fracture mechanism of the rock. When the microcrack density is low, tensile mode dominates the rock failure. Conversely, the shear mechanism dominates the rock fracture.

A novel mixed mode fracture criterion for functionally graded materials considering fracture process zone

A new mixed mode I/II fracture criterion based on strain energy release rate theory is proposed for investigating fracture behavior in cracked functionally graded materials. In this study, the crack is assumed to be located along the material gradation and within the brittle side of the material. For the first time in this type of material, the fracture process zone and the energy dissipated in this region are considered to enhance the prediction accuracy of the proposed criterion. The mechanical and fracture properties of the damage zone are characterized using the microcrack density parameter. A novel method for manufacturing functionally graded materials is introduced, offering numerous advantages by controlling the gel time of the resin. The critical mixed mode and pure mode II fracture toughness of the fabricated specimens are determined through three-point and four-point bending tests. A comparison of the experimental data with the fracture limit curve demonstrates the effectiveness of the newly proposed criterion for investigating mixed mode fracture in functionally graded materials

Mechanical properties and cracking strength estimation of high-strength engineered cementitious composites considering the fracture process zone

In the present study, the effect of flaws on the mechanical properties of high-strength engineered cementitious composites (HS-ECC) was investigated. Compressive tests, tensile tests, and electron microscope scanning microscopic tests were designed to explore the influence mechanism of flaws on mechanical properties. The results show that the compressive failure of HS-ECC was primarily characterized by a high density of vertical micro-cracks, and the specimen maintained exceptional structural integrity. All tested mix ratios demonstrated tensile strain hardening. Notably, the test groups with an 18 mm fiber length exhibited superior crack width control, with an average crack width of less than 30 μm. A new fiber bridging model was proposed, informed by microstructural analysis and crack opening displacement observations. A theoretical formula for the cracking strength of HS-ECC was developed based on the fracture process zone concept. The calculated initial crack strength closely matches the experimental values, with a discrepancy range of [0, 17 %]. This close agreement provides robust validation for the accuracy and reliability of the enhanced cracking strength calculation theory, thereby supporting its application in the design of ECC.

Effect of artificially induced microcracks near the rock surface on granite fragmentation performance under heating treatment

Various novel assisted drilling technologies enhance rock fragmentation performance by introducing microcracks on the rock surface to weaken rock strength. However, the quantitative relationship between artificially induced microcracks and rock fragmentation characteristics is not clear. In this study, we induced artificial microcracks of varying degrees on the rock surface through one-dimensional heat conduction. With the aid of the fluorescent resin, we visualized the microcrack patterns and quantitatively assessed the artificially induced microcracks. Subsequently, we performed quasi-static indentation tests on granite samples containing microcracks to establish the quantitative relationship between microcracks and rock fragmentation performance. The results indicate that the release of crystal water within the temperature range of 200 °C–300 °C is the primary factor leading to a significant increase in microcracks. Load drop signals correlate with the propagation of microcracks, including the competitive interactions between mechanically induced microcracks and artificially induced microcracks. Artificially induced microcracks require a certain initial length to continue propagating under mechanical stress, and excessively short microcracks are detrimental to subsequent propagation. A higher density of microcracks implies a more complex microcrack network, facilitating the merging of cracks to form rock chips under smaller mechanical loads. The consistency between the length density and number density of microcracks in influencing the crater parameters reflects their equal importance in affecting rock fragmentation performance. These findings could help determine the extent of rock weakening by artificially induced microcracks and reveal the mechanisms of rock fracture behavior influenced by microcrack, holding significant implications for the optimization of the process parameters of various assisted rock drilling techniques.

A simple extension of Timoshenko beam model to describe dissipation in cementitious elements

In this paper, an extension of the Timoshenko model for plane beams is outlined, with the aim of describing, under the assumption of small displacements and strains, a class of dissipative mechanisms observed in cementitious materials. In the spirit of micromorphic continua, the modified beam model includes a novel kinematic descriptor, conceived as an average sliding relevant to a density of micro-cracks not varying along time. For the pairs of rough surfaces, in which such a distribution of micro-cracks is articulated, both an elastic deformation and a frictional dissipation are considered, similarly to what occurs for the fingers of the joints having a tooth saw profile. The system of governing differential equations, of the second order, is provided by a variational approach, endowed by standard boundary conditions. To this purpose, a generalized version of the principle of virtual work is used, in the spirit of Hamilton–Rayleigh approach, including as contributions: (i) the variation of the inner elastic energy, generated by the linear elasticity of the sound material and, in a nonlinear way, by the mutual, reversible deformation of the asperities inside the micro-cracks; (ii) the virtual work of the external actions consistent with the beam model, i.e., the distributed transversal forces and the moments per unit lengths; besides these two contributions, constituting the conservative part of the system, (iii) the dissipation due to friction specified through a smooth Rayleigh potential, entering a nonlinear dependence of viscous and Coulomb type on the sliding rate. Through a COMSOL Multiphysics implementation, 1D finite element analyses are carried out to simulate structural elements subjected to three- and four-point bending tests with alternating loading cycles. The dissipation of energy is investigated at varying the model parameters, and the predictions turn out to be in agreement with preliminary data from an experimental campaign. The present approach is expected to provide a valuable tool for the quantitative and comparative assessment of the hysteresis cycles, favoring the robust design of cementitious materials.

Quantification of artificially induced microcracks and their effects on hard rock fragmentation performance and mechanical response characteristics

Microcracks have a significant effect on the physical and mechanical properties of rocks. Inducing artificial microcracks in rocks can reduce rock strength and decrease the energy required for rock fragmentation. Nevertheless, few attempts have been made to investigate the effect of microcracks on rock fragmentation performance and mechanical behavior, especially from the perspective of microcrack quantification. For this end, we heated granite samples to induce different degrees of microcracks. However, the parameters of microcracks are difficult to control. For the purpose of accurately characterizing the distribution of microcracks, we measured the microcrack parameters in detail. We visualized microcracks using the fluorescent epoxy method and quantified the microcrack parameters by image processing. Such a method suffered at the expense of losing some of the extremely small microcracks. But, on the other hand, a much larger field of view area is assured, allowing the data to be more representative. After the quantification of microcracks, we performed indentation tests on samples containing microcracks to analyze the mechanical response of tool-rock interaction and crater parameters. The results show that the lengths of individual thermally induced microcracks are distributed between 0.2 and 1.1 mm. At higher temperatures, thermal microcracks are dominated by intragranular microcracks leading to a more uniform distribution. The presence of microcracks can affect the fracture characteristics of rocks and a threshold exists. Compared with the unheated sample, a fivefold increase in the density and total length of microcracks reduces the peak force by 88% and 54%, and the absorbed energy by about 90% and 68%, respectively. Additionally, the comprehensive parameter (i.e., fractal dimension) is not an effective parameter in analyzing microcracks, and a single absolute metric (e.g., crack density, length, number, etc.) is recommended. This study is expected to provide a new perspective to understanding the relationship between microcrack parameters and rock fragmentation, and to provide a reference for applied research on new drilling techniques.Our study enhances the efficiency of drilling in hard rocks for geothermal resources by elucidating the role of microcracks in rock fragmentation. This research aligns with the goals of sustainable and cost-effective subsurface engineering, contributing to a net-zero energy future.

Dynamic fracture mechanism from a pre-existing flaw in granite: Insights from grain-based modelling

Both heterogeneity and pre-existing flaws are closely associated with the mechanical response of crystalline granite. To uncover the underlying mechanism, grain-based model (GBM) based on particle flow code (PFC), i.e., PFC-GBM, with different contacts between any two grains, was employed to carry out numerical calculations to investigate the effect of a single flaw with various inclination angles on the dynamic behavior of LdB granite. The failure pattern is identified through density and spatial distributions of microcracks, and the primary fracture directions are obtained by microcrack orientations. Microcracks are divided into inter-Grain and intra-Grain types, and these two types are further classified into more subtypes according to mineral composition. IG cracks typically form during the pre-peak stage and tend to emerge earlier than TG cracks. Conversely, TG cracks are predominantly created during the post-peak stage but constitute a significant proportion irrespective of flaw inclination angle. A novel method is also proposed to acquire high-stress particles, which promote the identification of dominant macrocrack paths. Finally, the effect of particle size is also systemically analyzed.

Influence of Interaction between Microcracks and Macrocracks on Crack Propagation of Asphalt Concrete.

This paper aims to reveal the interaction relationship between microcracks and macrocracks and the influence of the interaction on the crack propagation behavior. A theoretical model of asphalt concrete was established for the interaction between microcracks with different crack densities and a macrocrack. And a meso-structure model of AC-13 dense-graded asphalt concrete was established by combining the Talyor medium method and the DEM (discrete element method). Macro and micro parameters, such as the stress-strain characteristics, crack evolution parameters, and crack tip stress field, were obtained through a semi-circular bend virtual test and used to study the characteristics of crack propagation under the interaction between microcracks and the macrocrack. The results indicate that the interaction has an effect throughout the process of asphalt concrete damage, and shows shielding and acceleration effects as the microcrack density changes. When the microcrack density is low (f3 ≤ 0.8), the crack propagation process, which is affected by the interaction effect, exhibits significant differences, and the interaction effect shows the shielding effect. When the microcrack density is high (f3 > 0.8), the fracture stage is mainly affected by the interaction effect, which shows the acceleration effect. The results provide a predictive theoretical and numerical model for low-temperature cracking of asphalt pavement, and theoretical support for the design, maintenance, and upkeep of long-life pavement.

Failure envelope prediction of 2D SiCf/SiC composites based on XGBoost model

In this paper, a multiple failure mechanisms-based progressive damage model is developed to capture the mechanical response and defect-induced nonlinear behavior of 2D SiCf/SiC composites. This model is then adopted to simulate the stress–strain response of a representative volume element model under uniaxial loading, showing excellent agreement with experimental results. The effects of the volume fraction of SiC fibers, as well as those of the porosity and microcrack density of SiC matrix, on the deformation and damage behaviors of SiCf/SiC composites are predicted. Based on this, the failure envelopes related to micro-mesoscopic characteristics under combined loadings are generated as the database for the eXtreme Gradient Boosting (XGBoost) model training. Finally, a data-driven failure model is established for 2D SiCf/SiC composites, whose prediction is compared with the formal failure criteria. The results demonstrate that the data-driven 2D SiCf/SiC composite failure model is reliable in constructing the failure criteria related to micro-mesoscopic features.

Effect of Mineral Composition and Particle Size on the Failure Characteristics and Mechanisms of Marble in the China Jinping Underground Laboratory.

In deep underground engineering, the deformation, failure characteristics, and mechanism of surrounding rock under the influence of grain sizes and mineral compositions are not clear. Based on CJPL-II variously colored marbles, the differences in grain size and mineral composition of the marble were analyzed by thin-section analysis and XRD tests, and the effect of intermediate principal stress on the mechanical properties of marble was investigated. Both SEM and microfracture analysis were coupled to reveal the failure mechanisms. The results highlight that the crack initiation strength, damage strength, peak strength, and elasticity modulus of Jinping marble exhibit an increasing trend with an increase in intermediate principal stress, while the peak strain initially increases and subsequently decreases. Moreover, this study established negative correlations between marble strength, brittleness characteristics, and fracture angle with grain size, whereas positive correlations were identified with the content of quartz, sodium feldspar, and the magnitude of the intermediate principal stress. The microcrack density in marble was found to increase with larger grain sizes and decrease with elevated quartz and sodium feldspar content, as well as with increasing intermediate principal stress. Notably, as the intermediate principal stress intensifies and grain size diminishes, the transgranular tensile failure of marble becomes more conspicuous. These research findings contribute to the effective implementation of disaster prevention and control strategies.

Experimental Study on the Comparison between Network Microstructure Titanium Matrix Composites and Ti6Al4V on EDM Milling.

Network microstructure titanium matrix composites (NMTMCs), featuring Ti6Al4V as the matrix and network-distributed TiB whiskers (TiBw) as reinforcement, exhibit remarkable potential for diverse applications due to their superior physical properties. Due to the difficulty in machining titanium matrix composites, electrical discharge machining (EDM) stands as one of the preferred machining techniques for NMTMCs. Nevertheless, the compromised surface quality and the recast layer significantly impact the performance of the workpiece machined by EDM. Therefore, for the purpose of enhancing the surface quality and restraining the defects of NMTMCs, this study conducted comparative EDM milling experiments between NMTMCs and Ti6Al4V to analyze the effects of discharge capacitance, charging current, and pulse interval on the surface roughness, recast layer thickness, recast layer uniformity, and surface microcrack density of both materials. The results indicated that machining energy significantly influences workpiece surface quality. Furthermore, comparative experiments exploring the influence of network reinforcement on EDM milling revealed that NMTMCs have a higher melting point, leading to an accumulation phenomenon in low-energy machining where the reinforcement could not be completely removed. The residual reinforcement in the recasting layer had an adsorption effect on molten metal affecting the thermal conductivity and uniformity within the recasting layer. Finally, specific guidelines are put forward for optimizing the material's surface roughness, recast layer thickness, and uniformity, along with minimizing microcrack density, which attain a processing effect that features a roughness of Ra 0.9 μm, an average recast layer thickness of 6 μm with a range of 8 μm, and a surface microcrack density of 0.08 μm-1.

Mode-I failure and mechanical behavior of sandstone under cyclic loading: Laboratory testing and DEM simulation

To study the mode-I failure and mechanical behavior of rock under cyclic loading, the cracked chevron notched Brazilian disc (CCNBD) of sandstone was employed in this paper, and thus three different upper-limit loads cyclic tests were carried out, including 95 %SUL(static ultimate load) ∼ 35 %SUL, 85 %SUL ∼ 25 %SUL, 75 %SUL ∼ 15 %SUL. The 3D discrete element model of CCNBD specimen was built to study mechanical properties and cracking behavior at a meso-scale. Meanwhile, the effect of cyclic loading on microstructure characteristics and fracture process zone (FPZ) was discussed. The results show that cyclic loading has a weakening effect on fracture toughness, and a modified fracture toughness calculation method was proposed considering the effect of irreversible plastic deformation under cyclic loading. There are obvious stages of microcracking behavior under cyclic loading, specific for the condition of 85 %SUL ∼ 25 %SUL, and the microcrack density is positively correlated with the number of cycles. Meanwhile, the effect of cyclic load on sandstone microstructure contains weak-structure fracture effect and compaction effect, and they exist simultaneously and work together. In addition, cyclic loading has a great influence on the length of FPZ, and the length of FPZ under cyclic loading is greater than that under monotonic loading.

The influence of alien dislocations on the plasticity of [formula omitted]-axis Mg single crystals under tension and compression

Uniaxial tension and compression tests were conducted on as-grown [0001] Mg single crystals and on [0001] single crystals containing an alien distribution of basal dislocations to elucidate their effect on the deformation mechanisms and strain hardening. During tensile deformation, the basal dislocations induce elasto-plastic transition and micro-yielding that precede the gross deformation by twinning. They decrease the stress for twin nucleation, the tensile strength, and the failure strain compared to the virgin single crystals. The weakening of the microstructure and early failure are attributed to the higher density of micro cracks formed in the crystals with alien basal dislocations. The extraneous basal dislocations alter entirely the deformation mechanisms and strain hardening characteristic of [0001] single crystals under compression. They suppress the pyramidal slip as a dominant deformation mode and promote the gross deformation by cooperative basal slip and twinning during extended deformation plateau. The deformation twinning is of anomalous type, nucleating and propagating with the assistance of extraneous basal dislocations at the negative Schmid Factor and against the imposed compressive strain. τtw≈2.1±0.2MPa is found as the basal slip-assisted twinning stress in Mg.

Effect of Wet-Dry Cycling on the Microstructure of Various Weathering Grade Sandstone

This study investigated the effect of rock-water interaction on microstructural properties of various weathering grade sandstone. Sandstone samples were acquired from the Sor-Range coal mine area, Pakistan, and were investigated using a tabletop scanning electron microscope (SEM). The characteristics of microstructures from micrographs were obtained using ImageJ software. According to the findings an increase in wet and dry cycles significantly affects the microstructures (pore spaces and microcracks). The porosity and microcracks density of sandstone increases with the number of wet and dry cycles. Furthermore, the length of microcracks increases as the weathering grade increases. As variation in rock macroscopic mechanical characteristics is directly associated with the deterioration of microstructures. Therefore, analyzing the effect of water-rock interaction in various weathering grades of rock can offer a more accurate reference index for assessing the stability of geotechnical structures.

Development of a Laboratory Test Apparatus for Simulating Core Drilling under High In Situ Stress

Abstract Rock cores drilled under high in situ stress environments are inevitably permanently damaged due to the stress relief, which significantly affects the evaluation of the physical and mechanical properties of deep rocks. Quantitatively correlating this sampling damage with in situ stress distribution is challenging because of the complexity of the geological environment and the diversity of rock materials. To address this challenge, a laboratory test apparatus has been developed that can apply specific pressure to shallow rock materials to simulate high in situ stress environments and drilling–coring to simulate the sampling process of deep rock masses. The results of verification tests demonstrate that the integrity of cores gradually deteriorated as the sampling confining pressure increased. Moreover, simultaneous increases in the density and size of microcracks were observed within the cores, where these microcracks propagate through grain boundaries, generate intragrain and transgranular microcracks, extend outwardly to form macroscopic cracks, and enhance porosity. These findings confirm the applicability of the apparatus for conducting quantitative sampling damage studies. In the future, further investigations using the apparatus will be conducted to explore the mechanical attenuation patterns of rock cores, thereby providing a reference to evaluate rock mechanics parameters for engineering practices.

Research on the Influence Mechanism of Moisture Content on Macroscopic Mechanical Response and Microscopic Evolution Characteristic of Limestone

The uniaxial compression experiments and acoustic emission (AE) monitoring are conducted to investigate the macroscopic mechanical behavior and microscopic fracture characteristics of limestone samples with varying moisture contents. The findings revealed that as the moisture content increases from 0 to 6.6%, there is a decrease in peak stress and an increase in peak strain. A clear trend towards greater complexity in fracture characteristics is observed with increasing moisture content. In addition, AE activities demonstrate a heightened frequency, accompanied by an elevation in the corresponding multifractal parameter Δα as the moisture content rises. These variations are attributed to the increase in moisture content, which promotes the proliferation of small-scale microcracks and inhibits their evolution into large-scale microcracks. Consequently, the damage and failure process of the limestone samples transitions from being predominantly controlled by a few large-scale microcracks to being collectively influenced by a multitude of small-scale microcracks as the moisture content increases. In conjunction with the Criterion of Microcrack Density, the correctness of the analysis above is substantiated through mathematical derivation. Further, a quantitative model that links the microcrack system to moisture content is established based on the multifractal parameter Δα. Following this, a characterization model that depicts the macroscopic mechanical properties of limestone affected by moisture content is developed. This model effectively encapsulates the quantitative relationship between moisture content and the macroscopic characteristics of limestone and is validated through fitting experimental data. This research contributes to understanding the macroscopic mechanical response and microscopic fracture characteristics of limestone samples with different moisture contents, providing valuable insights and guidance for ensuring safety during engineering construction processes.

A review on gas permeability of polymer matrix composites for cryogenic applications

Fiber-reinforced polymer matrix composites are increasingly considered for lightweight cryogenic pressure vessels due to their excellent combination of tailorability, specific mechanical properties, and relatively low coefficients of thermal expansion. However, significant challenges must be overcome to fully utilize PMCs for cryogenic fuel tanks in terms of transverse microcracking and subsequent permeation of cryogenic fuel. Gas permeation and microcrack densities of cryogenically cycled composites are highly influenced by their layup, ply thickness, load case, and manufacturing defects like voids and resin rich zones. There has been a significant amount of research on measuring gas permeation of composites fatigued under pure thermal or uniaxial thermo-mechanical stresses. However, results demonstrate that the gas permeability should be measured under biaxial thermo-mechanical stresses to properly gauge the leakage characteristics of damaged composites. This paper summarizes the results from over a hundred papers on the key parameters that influence the gas permeability of composites, appropriate testing methods to cycle composites for permeability measurement, methods to limit the evolution of transverse microcracks, and materials traditionally used for the fabrication of all-composite cryogenic fuel tanks. Thin plies and nanofiller-toughening of the matrix have been shown to provide significant improvements in transverse microcrack suppression within cryogenically cycled composites.

A dissipation model for concrete based on an enhanced Timoshenko beam

<p>A novel Timoshenko beam model enriched to account for dissipation in cement-based materials was presented in this paper. The model introduced a new variable representing the relative sliding inside microcracks within the material. In the paper, the microcrack density was not supposed to increase, assuming a small deformation regime that implied no damage growth. The model utilized an expanded version of the principle of virtual work whose contributions came from external forces, internal elastic forces, and dissipation due to the microcrack's microstructure. The elastic energy included terms related to microcrack sliding and micro-macro interactions, accounting for nonlinearity in the material behavior. Numerical simulations, conducted using the finite element method, evaluated the mechanical properties of cement-based materials under three-point flexural tests and compression tests. These tests enabled the assessment of the material dissipative behavior under cyclic loading. Results showed dissipated energy cycles and mechanical responses influenced by the microcrack mechanics. Additionally, a parametric study, varying the friction force amplitude, revealed its impact on dissipated energy. The study highlighted a non-monotonic relationship between friction force amplitude and dissipated energy, with an optimal value maximizing dissipation. Overall, the model provided insights into the mechanics of cement-based materials, particularly regarding dissipation, which was essential for understanding their behavior in structural applications.</p>

Deterioration of equivalent thermal conductivity of granite subjected to heating-cooling treatment

Understanding the thermal conductivity of granite is critical for many geological and deep engineering applications. The heated granite was subjected to air-, water-, and liquid nitrogen (LN2-) coolings in this context. The transient hot-wire technique was used to determine the equivalent thermal conductivity (ETC) of the granite before and after treatment. The deterioration mechanism of ETC is analyzed from the meso-perspective. Finally, the numerical model is used to quantitatively study the impact of cooling rate on the microcrack propagation and heat conduction characteristics of granite. The results show that the ETC of granite is not only related to the heating temperature, but also affected by the cooling rate. The ETC of granite decreases nonlinearly with increasing heating temperature. A faster cooling rate causes a greater decrease in ETC at the same heating temperature. The higher the heating temperature, the stronger the influence of cooling rate on ETC. The main explanation for the decrease in ETC of granite is the increase in porosity and microcrack density produced by the formation and propagation of pore structure and microcracks during heating and cooling. Further analysis displays that the damage of granite at the heating stage is induced by the difference in thermal expansion and elastic properties of mineral particles. At the cooling stage, the faster cooling rate causes a higher temperature gradient, which in turn produces greater thermal stress. As a result, it not only causes new cracks in the granite, but also aggravates the damage at the heating stage, which induces a further decrease in the heat conduction performance of granite, and this scenario is more obvious at higher temperatures.

Ultra-stretchable, sensitive and breathable electronic skin based on TPU electrospinning fibrous membrane with microcrack structure for human motion monitoring and self-powered application

With the rapid development of wearable electronic, electronic skin with excellent performance for human motion detection have been widely investigated recently. In this work, a multifunctional electronic skin with three-dimensional conductive network skeleton was prepared based on synergistic conductive filler (carboxylated multi-walled carbon nanotubes (C-MWCNT) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS)) decorated breathable thermoplastic polyurethane (TPU) electrospinning fibrous membrane. Then, microcrack structure was constructed via pre-stretching and the strain sensitivity of the resultant C-MWCNT/PEDOT:PSS/TPU (CPT) conductive fibrous membrane could be effectively adjusted by changing the microcrack density. Due to the three-dimensional conductive network skeleton, microcrack structure and the bridging effect of C-MWCNT between the adjacent crack fragments, ethylene glycol treated CPT (mass ratio of C-MWCNT and PEDOT:PSS is 9/1) (e-CPT9/1) strain sensor exhibited high sensitivity (6008.3), wide response range (680 %), fast response/recovery time (200 ms/200 ms), low detection limit (0.5 %), excellent durability and repeatability (6000 cycles). The excellent strain sensing performances enables it to accurately monitor motion activities and physiological signals, and can also be used as a smart sensing glove to identify different letters gesture and numeric gestures. Furthermore, owing to the photothermal conversion ability and thermoelectric effect of C-MWCNT and PEDOT:PSS, the obtained e-CPT9/1 device also displayed efficient “light-thermal-electric” conversion ability and showed the great potential as self-powered strain sensor.