Static Fracture Research Articles

Static and dynamic fracture behavior of rock-concrete bi-material disc with different interface crack inclinations

The fracture behavior of rock-concrete bi-material structures with interface crack is of great significance to the stability of construction projects in rock engineering. Dynamic testing of cracked straight-through Brazilian disc (CSTBD) samples was performed using a split-Hopkinson pressure bar (SHPB) system. The fracture development of rock-concrete bi-material was monitored by the digital image correlation (DIC) technique. A static fracture test using the MTS322 hydraulic servo-controlled testing system was also carried out for comparison. The results show that three typical fracture patterns can be identified for CSTBD samples under both static and dynamic loading. At a smaller interface inclination angle, the disk samples fracture along the interface, while at a larger interface inclination angle, the samples suffer tensile fracture along the loading direction. The increase of strain rate leads to an increase in the number of secondary cracks. As the inclination of interface increases from 0° to 75°, the dissipated energy increases gradually. When the inclination exceeds 75°, the dissipated energy turns to weaken. The difference in peak dissipated energy between different inclination angles weakens as the strain rate increases. The dimensionless stress intensity factors (SIFs) at the two crack tips are different, and increasing the crack length-diameter ratio will enlarge the difference. The interface inclination angle has a significant effect on both the static and dynamic fracture toughness of CSTBD samples. As the inclination of the interface increases, the difference between mixed-mode static and dynamic fracture toughness also increases. The dependence of dynamic fracture toughness on inclination is significantly higher than that of static fracture toughness, and the ratio between dynamic and static fracture toughnesses increases with increasing loading rate.

Mixed mode fracture parameters and fracture characteristics of diorite using cracked straight through Brazilian disc specimen

In this study, the cracked straight through Brazilian disc (CSTBD) specimen was applied to study the I/II mixed mode static fracture of diorite. The fracture load and fracture toughness for different prefabricated crack angles β were determined. The fracture and morphological characteristics were analyzed using digital image correlation (DIC), scanning electron microscope (SEM) and 3D topography scanning techniques. In addition, the key fracture parameters such as fracture energy, crack mouth opening displacement (CMOD) and fracture process zone (FPZ) were characterized, and a fracture energy calculation method considering the primary crack growth was proposed. The results show that the fracture mechanical behavior and fracture trajectories are controlled by the crack angle. At the millimeter measurement scale, the fractal dimensions of fracture surfaces do not vary with crack angle. Further SEM observation shows that intergranular fracture and transgranular fracture are the dominate micro fracture modes of fracture surfaces under mode I and mode II loading, respectively. With the increase of crack angle, the fracture energy first increases and then decreases, while the allowable CMOD decreases monotonically and even appears negative when β ≥ 45°. Based on the displacement gradient method, the calculated width of FPZ for the mode I fracture specimen at peak load is 0.5–1.4 mm and the length is 2.66 mm. Finally, the stress-based and strain-based fracture criteria were modified. It is found that the proposed EEMTSN criterion has the best prediction effect on the mixed mode fracture toughness of diorite.

Fracture modeling by the eigenfracture approach for the implicit material point method framework

AbstractThe material point method (MPM) is efficiently applied for the simulation of structures undergoing large deformations where fracture and crack initiation are expected. The eigenfracture approach is introduced in the paper at hand for the implicit MPM to model crack development and propagation in static and dynamic fracture of brittle elastic materials. Eigenfracture is an energetic fracture formulation applied in the postprocessing step of the implicit MPM, making its implementation relatively straightforward. Furthermore, the driving energy used to check crack propagation is evaluated using the representative crack elements (RCE), by which the crack is modeled as a discrete phenomenon. The RCE approach shows more realistic results compared to other split models. Additionally, the fracture description of reinforced materials within the MPM is also presented in this article by coupling truss finite elements to the MPM, considering the bond stress‐slip constitutive model. Two‐ and three‐dimensional problems in static and dynamic applications are presented to assess the efficacy of the approach.

A dynamic fracture model combining with Laplace transform and synchronous iteration method for transient behavior analysis of a four-zone system

A robust and generic semi-analytical model with the capture of dynamic fracture behaviors under long-term pumping rate condition is developed for transient flow analysis in this four-zone system. To characterize the variations of fracture length, the improved pressure-dependent dynamic fracture factor is introduced and incorporated into this model. The Laplace domain with predetermined time discretization and synchronous iteration technique are deployed to obtain the solutions of pressure and pumping rate with the least computational burden. Meanwhile, the stability and convergence of this semi-analytical model can be met within the discrete time. Furthermore, the pressure and pumping rate solutions of this model under the static fracture condition are in good agreement with those of the constant length fracture, which verifies the reliability of this model.The dynamic fracture model with the four -zone system develops five flow stages on the dimensionless pressure and its derivative curves: fracture bilinear flow, dynamic fracture flow, inner area linear flow, transitional flow and boundary-dominated flow. The dynamic fracture behavior is mainly reflected in the obviously positive upwards and pressure derivative curve presents a higher than unit slope. Moreover, the significant decrease of flow rate indicates that fracture closure could result in a rapid decline in pumping rate, which might be the reason why the pumping rate decrease quickly during the long-term pumping period. As the shrinkage coefficient increases, fractures are closed from abruptly to gradually, and typical signatures of fracture closure may be hidden if the shrinkage factor is too small, which may be caused by the instantaneous pressure depletion in the fractures. With the decrease of retained fracture coefficient, there is greater in the positive upward of transient pressure behavior and a lower in pumping rate. As a result, the flow rate will be seriously overestimated if the fracture closure is not considered especially for the tight formation.

A two-level nesting smoothed extended meshfree method for static and dynamic fracture mechanics analysis of orthotropic materials

This paper presents a two-level nesting smoothed extended mesh-free method (S-XMM-N) for the static and dynamic fracture mechanics analysis in orthotropic materials. To capture the jump of displacement fields across the crack surface, as well as singularities of stress fields in the vicinity of the crack tip, both Heaviside function and asymptotic solutions from the orthotropic fracture modeling are incorporated into the radial point interpolation shape functions associated with the partition of unity approach. To improve the accuracy and accelerate the computation of the extended mesh-free method, the two-level nesting smoothing integration scheme based on the first and second-level triangular smoothing sub-domains is developed to perform the stiffness integration. Compared to the extended mesh-free method using the conventional Gaussian quadrature, the presented S-XMM-N uses even less integration sampling points. At the same time, the complex and time-consuming derivative calculation of extended shape functions is completely avoided. This leads to the dramatically improvement of efficiency. Moreover, the presented method gives very exactly numerical solutions by optimally combining the contributions from the two-level nesting smoothing sub-domains based on the Richardson extrapolation method. We use the interaction integral method in conjunction with the asymptotic near crack tip fields of orthotropic materials to extract the static and dynamic stress intensity factors. The numerical solutions obtained from the S-XMM-N are further compared with reference solutions from the literature to verify the accuracy of the proposed method.

Evaluation of the effect of temperature and pressure on the process of combating loss of circulation using fibrous and granular materials

This study aimed to evaluate the influence of pressure and temperature in combating the loss of circulation, using granular and fibrous materials in different techniques of mitigation. Experimental studies were performed using water-based fluids containing polymers as viscosifiers and lost-circulation materials (LCM). Two kinds of tests were done in static and dynamic conditions. In the static approach, the filtration and fracture sealing tests were performed in a 2 mm slot fracture in High-Temperature/High-Pressure (HTHP) filtration cell. For the dynamic approach, two Fracture Flow Simulators (FFS) were used. A FFS 1.0 operated under low pressure and ambient temperature which allowed the visualization of the fluid flow and the structure of the forming seal. In the FFS 2.0, the tests were applied in cases of high pressure and high temperature. Based on the test results, it was possible to identify the sealing mechanisms in dynamic and static approaches where the studied suspensions and kinds of LCM proved to be efficient in sealing fractures dynamically. The data obtained from the simulators were used to analyze the behavior and allow to phenomenologically evaluate the different mechanisms of action of LCM and even the most efficient blends of materials. The studies of the effect of temperature, pressure, and composition of granular and fibrous materials and a blend of them in the combat of loss of circulation showed that the temperature had a more significant effect on the volume of fluid lost. It was found that the optimized blend composition was made of 75% granular and 25% fibrous materials allowing those materials to be applied more efficiently in combating loss of circulation.

Joints properties in rotary friction welding of AA5083-H112 aluminium alloy

Rotary friction welded joints of AA5083-H112 aluminium alloy rods with diameter of 15 mm and length of 50 mm were produced at various rotational speeds. The current research is aimed to understand the static and fatigue properties of welding joints. Several experiments were carried out including macrostructure and microstructure observations, hardness measurements, tensile testing, residual stress measurements by neutron diffraction, rotary bending fatigue tests and fractography. The results showed that the static fracture occurred at the base metal away from the weld metal region for all weld joints under study with the average ultimate tensile strength of 272.7 MPa. In this condition, the joint efficiency was higher than 100%. It was found that the high strength of the weld joints was associated with fine-grained microstructure. On the other hand, fatigue property of the weld was influenced by both welding microstructure and residual stress. This argument was supported by the facts that the initial crack occurred at HAZ at which the residual stress was tensile and then followed by fatigue crack growth from HAZ towards TMAZ.

Damage accumulation and limit states under the low-cycle loading of structural softening steel

Determination and study of patterns of deformation and fracture of structural materials under cyclic loading is an important fundamental scientific problem. The kinetics of damage accumulation in softening TC (12Kh2MFA) structural steel under low-cycle loading is investigated in the paper based on the unified strain-kinetic criterion of fatigue fracture developed by the author. The damaging role of plastic and elastic strain depending on the loading (durability) is shown. Limit states and peculiarities of their occurrence during static, quasi-static, and fatigue failure are described. The force and deformation parameters determining the load-bearing capacity of the material and the nature of its exhaustion under static and cyclic loading have been established. The critical values of deformation and strength characteristics of steel under soft and hard loading are obtained. It is noted that it is reasonable to use these characteristics when modeling the stress–strain states. A method for determining the cyclic behavior of the material (hardening, softening, stabilization) by static fracture curves is proposed. The possibility of describing the kinetics of damage accumulation and limit states of softening materials by the strain-kinetic criterion of fatigue fracture is confirmed.

Effect of initial damage state on static and dynamic fracture of concrete with different sizes: An experimental study

This paper presents a systematic experimental investigation to evaluate the effect of the initial damage degree on static and dynamic compressive/splitting-tensile failure behaviors of concrete cubes with various structural sizes. The experimental parameters involve three initial compressive damage degrees (0%Pmax,s, 40%Pmax,s, and 80%Pmax,s), two loading strain rates (ε̇ = 10−5/s and 10−2/s), and five geometric dimensions (side length 75, 100, 150, 200, and 300 mm). Test results indicate that as the initial damage degree increases, both static and dynamic nominal strength are reduced. The influence of initial damage degree on dynamic failure strength is more significant than that on static strength. Compared to dynamic compressive strength, the initial damage degree has a more significant influence on dynamic splitting tensile strength. The influence of geometric dimension on nominal strength is weakened with the increasing loading strain rate. The increasing initial damage can enhance the influence of geometric dimension on nominal strength, resulting in a more obvious size-effect.

Fracture Resistance and Microleakage around Direct Restorations in High C-Factor Cavities.

The aim of this research was to evaluate the mechanical impact of different direct restorations in terms of fracture resistance, and subsequent fracture pattern, in occlusal high C-factor cavities. Furthermore, the adaptation of different direct restorations in the form of gap formation was also evaluated. Seventy-two intact mandibular molars were collected and randomly distributed into three groups (n = 24). Class I occlusal cavities with standardized dimensions were prepared in all specimens. After adhesive treatment, the cavities were restored with direct restorations utilizing three different materials. Group 1: layered conventional packable resin composite (Filtek Ultimate), Group 2: bulk-fill resin composite (SDR), Group 3: bulk-fill short fibre-reinforced composite (SFRC; everX Posterior) covered with packable composite occlusally. Half of the restored specimens underwent static load-to fracture testing (n = 12/group), while the rest underwent sectioning and staining for microleakage evaluation and gap formation analysis. Fracture patterns were evaluated visually among the mechanically tested specimens. The layered composite restoration (Group 1) showed significantly lower fracture resistance compared to the bulk fill groups (Group 2, p = 0.005, Group 3, p = 0.008), while there was no difference in fracture resistance between the other groups. In terms of gap formation values, the layered composite restoration (Group 1) produced significantly higher gap formation compared to the bulk-fill groups (Group 2, p = 0.000, Group 3, p = 0.000). Regarding the fracture pattern, SFRC (Group 3) produced the highest number, while SDR (Group 2) produced the lowest number of repairable fractures. The use of bulk-fill resin composite (fibre or non-fibre-reinforced) for occlusal direct restorations in high C-factor cavities showed promising achievements regarding both fracture resistance and microleakage. Furthermore, the use of short fibre-reinforced bulk-fill composite can also improve the fracture pattern of the restoration-tooth unit. Bulk-fill materials provide a simple and effective solution for restoring and reinforcing high C-factor occlusal cavities.

Fatigue crack propagation and fracture toughness of cortical bone are radiation dose-dependent.

Cortical bone allograft sterilized with a standard γ-radiation dose of 25-35kGy has demonstrated reduced static and cyclic fracture resistance compared with unirradiated bone. To mitigate radiation damage, we recently observed a dose-dependent response of high-cycle fatigue behavior of human cortical bone from 0 to 25 kGy, with lower doses exhibiting logarithmically longer fatigue lives. The objectives of this study were as follows: (1) to determine whether fracture toughness, work-to-fracture, and fatigue crack propagation resistance of human cortical bone are also radiation dose-dependent, and (2) to determine the associations of radiation dose and a Raman biomarker for collagen disorder with fracture properties. Compact tension specimens were machined from two donor femoral pairs and allocated to four treatment groups: 0 (unirradiated control), 10, 17.5, and 25 kGy. Fracture toughness specimens were monotonically loaded to failure and the critical stress intensity factor (KC ) was determined. Work-to-fracture was calculated from the load versus displacement integral up to fracture. Fatigue crack propagation specimens were cyclically loaded under constant room-temperature irrigation and fatigue crack growth rate (da/dN) and cyclic stress intensity (∆K) were calculated. Fracture toughness, work-to-fracture, and fatigue crack propagation resistance decreased 18%, 33%, and 15-fold from 0 to 25 kGy, respectively (p < 0.05). Radiation dose was more predictive of fracture properties than collagen disorder. These findings support that quasi-static and fatigue fracture properties of cortical bone are radiation dose-dependent within this dose range. The structural alterations arising from irradiation that cause these losses in fracture resistance remain to be elucidated.

Experimental and numerical investigations of the fracture in 3D-printed open-hole plates

In the current study, we investigated mechanical strength and fracture behavior of 3D-printed open-hole plates. To this aim, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) are used for fabrication of specimens based on FDM technique. Since ratio of the specimen width to the hole diameter (W/D) has influence on the structural integrity of the part, we have printed specimens with two hole diameters. Particularly, specimens with W/D of 3 and 6 were designed and fabricated. Based on a series of tensile tests under static loading conditions, fracture load and stress–strain relationship of the plates are determined. Parallel to the experimental practice, a finite element model a series of finite element analyses were conducted to simulate cracking behavior of the aforementioned specimen. The model is based on phase-field fracture. The model parameters is calibrated based on the data from experiment or reported properties in the literature. Finally, results of the numerical calculations are reported which shows a very well agreement to those from experimental measurement. The outcome of this study can be utilized for future design, development, optimization, and next computational modeling of 3D-printed open-hole plates.

Effects of the embedding of cohesive zone model on the mesoscopic fracture behavior of Concrete: A case study of uniaxial tension and compression tests

The application of the Cohesive Zone Model (CZM) in concrete meso-mechanics solves the nonlinear problem of material crack tip well. At present, the application methods of CZM in concrete mesoscopic models include the bond mechanics characterization of the aggregate-mortar interface transition zone (ITZ) and the characterization of fracture characteristics between material micro-elements. From this, two different numerical models were derived—the combined Finite Discrete Element (FDEM) model and the Cohesive Finite Element (CFEM) model. To evaluate the difference between the two numerical models and the traditional Finite Element (FEM) model in simulating concrete mechanical behavior and crack propagation, a 3D concrete mesostructure modeling algorithm was developed in this study, including innovations in gravitational self-compacting of polyhedral aggregates. After that, the FDEM model and the CFEM model were successfully constructed based on the FEM model. Through uniaxial compression and tensile numerical simulations, it was found that the CFEM model is more in line with the theoretical and experimental mechanisms in the characterization of the static mechanical behavior and fracture process of concrete. The fracture failure angle variable defined by the CFEM model revealed that the compressed concrete material exhibited better strength and toughness due to a higher damage degree and more energy-consuming cracking mechanism. The above findings to a certain extent promote the future development of CZM in the field of concrete meso-mechanics.

Influence of Microstructure on Static and Cyclic Fracture Toughness of EN-GJS-600-3 Nodular Cast Iron

In this paper, the effect of microstructure of a thick-walled rotor shaft for wind turbines on fracture toughness properties has been investigated. The relevant nodular cast iron grade EN-GJS-600-3 was processed using chill casting technology. Due to different solidification conditions over the wall thickness, heterogeneous microstructures were formed. To illustrate the influence of the microstructure gradient caused by chill casting technology, specimens were taken from different sample positions in the cross section of the casting component. A detailed metallographic analysis revealed essential differences in microstructure. The crack growth resistance under quasi-static loading conditions and the fatigue crack propagation under cyclic loading conditions were measured. The results of the static fracture mechanics investigations revealed that fracture toughness is strongly influenced by the microstructure of this pearlitic ductile iron grade. On the other hand, cyclic fracture mechanics analysis showed that the complex formation of the microstructure has only a minor effect on the fatigue threshold value, but microstructure has a significant effect on the stable crack growth. For the assumed load cases, it was shown that microstructure can be a dominant factor on the mechanical and fracture toughness properties.

Decompaction wave propagation in a vibrated fine-powder bed.

We experimentally study the crack formation and decompaction-wave propagating in a vibrated powder bed consisting of glass beads of 5 μm in diameter. The vibrated powder bed exhibits three distinct phases depending on the vibration conditions: consolidation (CS), static fracture (SF), and dynamic fracture (DF). Particularly, we found an upward wave propagation in the DF regime when the powder bed is strongly vibrated. As a remarkable feature, we found that in fine cohesive powders, the decompaction-wave propagation speed normalized to gravitational speed is independent of the shaking strength. This result implies that the wave propagation speed is governed by the balance between gravity and cohesion effect rather than vibration strength. We also explore the universality of wave propagation phenomenon in coarser and low-density granular powders.

Finite element and in vitro study on biomechanical behavior of endodontically treated premolars restored with direct or indirect composite restorations

Objectives of the study were to investigate biomechanical properties of severely compromised premolars restored with composite restorations using finite element analysis (FEA), and in vitro fracture resistance test. A 3-D model of an endodontically treated premolar was created in Solidworks. Different composite restorations were modelled (direct restoration-DR; endo-crown-EC; post, core, and crown-C) with two different supporting tissues: periodontal ligament/alveolar bone (B), and polymethyl methacrylate (PMMA). Models were two-point axially loaded occlusally (850 N). Von Mises stresses and strains were calculated. The same groups were further tested for static fracture resistance in vitro (n = 5, 6.0 mm-diameter ball indenter, vertical load). Fracture resistance data were statistically analyzed (p < 0.050). The highest stresses and strains in all FEA models were observed on occlusal and vestibular cervical surfaces, corresponding to fracture propagation demonstrated in vitro. C showed the lowest stress in dentin, while EC showed lower stresses and strains in crown cement. B models demonstrated larger high stress areas in the root than PMMA models. No significant differences in fracture resistance (N) were observed between groups (DR: 747.7 ± 164.0, EC: 867.3 ± 108.1, C: 866.9 ± 126.3; p = 0.307). More conservative restorations seem a feasible alternative for endodontically treated premolars to conventional post-core-crown.

A coupled phase field formulation for modelling fatigue cracking in lithium-ion battery electrode particles

Electrode particle cracking is one of the main phenomena driving battery capacity degradation. Recent phase field fracture studies have investigated particle cracking behaviour. However, only the beginning of life has been considered and effects such as damage accumulation have been neglected. Here, a multi-physics phase field fatigue model has been developed to study crack propagation in battery electrode particles undergoing hundreds of cycles. In addition, we couple our electrochemo-mechanical formulation with X-ray CT imaging to simulate fatigue cracking of realistic particle microstructures. Using this modelling framework, non-linear crack propagation behaviour is predicted, leading to the observation of an exponential increase in cracked area with cycle number. Three stages of crack growth (slow, accelerating and unstable) are observed, with phenomena such as crack initialisation at concave regions and crack coalescence having a significant contribution to the resulting fatigue crack growth rates. The critical values of C-rate, particle size and initial crack length are determined, and found to be lower than those reported in the literature using static fracture models. Therefore, this work demonstrates the importance of considering fatigue damage in battery degradation models and provides insights on the control of fatigue crack propagation to alleviate battery capacity degradation.

Design, 3D printing, and evaluation of full-contact dental models for denture tests.

The full-contact model has been widely used in tooth preparation and prosthesis fabrication. However, it is rarely used in denture tests. The purpose of the present study was to design a suitable full-contact dental model for denture tests. A standard dental model with the complete tooth morphology was raster scanned and 3D reconstructed. Then, the positioning and fixing surfaces of the dental model were reshaped. The dental model was digitally trimmed into two parts: a fundamental part and a replaceable part. The modular design was presented according to dentition defects around the first molar. The prepared tooth replicas were designed through preparation/scanning/registration/separation sequences. The dental model was fabricated by stereolithography (SLA) 3D-printing rapid prototype technology. The static fracture force of the dental model was predicted using the finite element method. The effects of the four design methods on the suitability of the five testing operations (abutment fabrication, prosthesis fabrication, assembling, loading, and observation) were quantitatively analyzed. The static tests of three fixed partial dentures (FPDs), including tooth-supported, implant-supported, and tooth-tooth-supported prostheses, were conducted to investigate the fracture feature. The dynamic test of a removable partial denture (RPD) was undertaken to study the wear characteristic. The dental model could bear the maximum fracture strength of 4268.3 N. Seven positive and two negative effects of the design methods were produced. The maximum fracture strength of the FPDs were 1331.2 N, 1356.7 N, and 1987.7 N. The wear facets of the RPD in the dynamic denture test were distributed in three regions. The force capacity of the full-contact dental model allows the application of static denture tests. The dental model provides improvements in fixture design, removable design, and replica design for the testing operations. The dental model is recommended more in the dynamic test than in the static test.

Fracture toughness weakening effect of high static pre-loaded CSTBD granite subjected to low frequency dynamic disturbance during the rock fracture

Highly static pre-loaded rock with cracks will be generated during the deep rock engineering excavation, is subjected to low-frequency dynamic disturbance (Fd) to induce fracture failure. To investigate the fracture mechanisms of the high static pre-loaded rock with cracks, subjected to low-frequency dynamic disturbances, several tests were conducted on cracked straight through Brazilian disc (CSTBD) granite specimens using the MTS system. Based on the average static peak fracture load (Fmax) of the CSTBD specimens, three high static pre-load levels, Fp (70%, 80%, and 90% of Fmax), and the corresponding disturbance amplitude, Fa (30%, 20%, and 10% of Fmax), and low-frequency disturbance frequency, f (1, 5, 10, 30, and 50 Hz), were determined. The results revealed that the fracture toughness of the static pre-loaded CSTBD specimens subjected to low-frequency dynamic disturbance was lower than that under static load. The higher the Fp, the more significant is the decrease in fracture toughness with f. Comprehensive analysis indicates that the degree of fracture toughness weakening is highly dependent on the Fp, Fd induces strength weakening, and f affects the weakening degree.

Experimental Study of Fatigue and Fracture Behavior of Carbon Fiber-Reinforced Polymer (CFRP) Straps.

The hanger is one of the important components for through and half-through arch bridges. Conventional steel hangers are vulnerable to corrosion due to corrosive environments. Therefore, a new type of bridge hangers consisting of Carbon Fiber-Reinforced Polymer (CFRP) straps was developed recently. The CFRP straps are self-anchored, which is formed by layers-winding, and they have great advantages in corrosive environments such as high resistance to corrosion. In this study, the fatigue and fracture behavior of CFRP straps has been experimentally investigated. Firstly, the tensile testing of four CFRP strap specimens was conducted to investigate the static fracture behavior of CFRP straps, and three stages were observed, including delamination, cracking, and brittle rupture. Then, a fatigue test of thirty-nine specimens (four groups) was carried out to study the fatigue behavior of CFRP straps, where two types of pins, titanium alloy pin and CFRP pin, and two loading frequencies, 10 Hz and 15 Hz, were used. The number of cycles to failure, displacement, fatigue failure strain, outside surface temperature at the vertex of specimen, and scanning electron microscope (SEM) photographs were recorded and analyzed to investigate the fatigue behavior of CFRP straps. The experiment results show that the temperature development at the vertex of the CFRP strap varies obviously if different pins are used due to the different friction coefficients. In addition, the fatigue life of CFRP straps decreases significantly with the increase in loading rate for the titanium pin, while it only reduces slightly with the increase in loading rate for the CFRP pin.