Dynamic Strain Research Articles

A Method for Plotting Failure Envelopes of Unidirectional Polymer Composite Materials under Different Strain Rates

This article emphasizes the significance of investigating the nonlinear behavior and strength characteristics of polymer composite materials under various strain rates. The study utilizes test results of a unidirectional (UD) composite material subjected to compression at different angles relative to the reinforcement direction, using quasi-static, static, and dynamic strain rates. The analysis focused on a UD layer experiencing compressive stresses perpendicular to the fiber reinforcement and in-plane shear stresses. A novel model is presented, enabling the calculation and prediction of the strength of a UD composite under uniaxial loading at different angles to the fiber direction, considering various strain rates. The developed model facilitates the derivation of equations for the failure envelopes of UD Carbon Fiber-Reinforced Polymers (CFRPs) under quasi-static, static, and dynamic loading conditions. To construct the failure envelopes of CFRPs, it is necessary to acquire experimentally determined values of tensile and compressive strength in the direction perpendicular to the reinforcement, as well as the ultimate strength in uniaxial compression of a specimen with reinforcement at a 45° angle to the loading axis. The failure envelopes generated using the proposed model exhibit excellent agreement with experimental data, with coefficients of determination ranging from 0.864 to 0.957, depending on the deformation rate. Consequently, the developed model holds promise for predicting the strength of other UD polymer composite materials.

A Mass-In-Mass Metamaterial Design for Harvesting Energy at a Broadband Frequency Range

A novel deterministic method to harvest energy within a broadband frequency (0~25 kHz) from a mass-in-mass metamaterial is presented herein. Traditional metamaterials are composed of multiple materials (named as resonators and matrix) with different mechanical properties (e.g., stiffness, density). In this work, the stiffnesses of matrix materials are altered systematically to allow diversified property mismatches between the constituent components to introduce local resonance in the unit cell. While local resonance leverages wave energy passing through the acoustic metamaterials trapped within the relatively soft matrix as dynamic strain energy, a strategic and deterministic methodology is investigated to obtain a broadband local resonance frequency. The frequency band can then be utilized to harvest the trapped energy by embedding a smart material inside the matrix which is capable of electromechanical transduction (e.g., lead zirconate titanate). This concept has been proved numerically by harvesting energy at a broadband frequency with a power density of ~10 μW/in2. Finally, an experimental study is performed to prove the hypothesis proposed in this article.

Shock-induced transformation of nitinol shape memory alloy: Effect of stress state on transformation

Due to its numerous practical applications and intriguing phase transformation behavior, shape memory alloys (SMAs) have garnered significant research and development interests. In the past, most studies on the mechanical behavior of SMAs have been conducted under uniaxial stress loadings. Limited research on SMAs under shock loading has not provided conclusive results regarding their transformation behavior and transformation stress under such loading. Additionally, there is a lack of comprehensive understanding regarding the effects of different stress states on transformation behavior. The main objectives of this study are to address these issues. To achieve these objectives, a series of shock wave experiments were designed and conducted. Additionally, quasi-static and dynamic uniaxial stress experiments were carried out to establish a baseline for comparison. The results revealed that the transformation stress under dynamic uniaxial strain shock loading was approximately 1.92 GPa in contrast to 0.5 GPa (quasi-static) to 0.8 GPa (dynamic) observed in uniaxial stress loading. The transformation behavior exhibited noticeable rate sensitivity for both types of loading. There appeared to be a critical strain rate above which the austenite phase was driven to a metastable state. This estimated critical axial strain rate along the loading direction was approximately 2 × 103/s–4 × 103/s for uniaxial stress loading and approximately 2 × 106/s for uniaxial strain loading. The apparent high transformation stress for uniaxial strain loading can likely be attributed to a combination of high-pressure confinement and high strain rate. However, determining their relative contributions remains an open issue.

Annealing‐Induced Dynamic Strain Evolution in Cycled High‐Ni Layered Oxides Revealing Latent Lattice Imperfections

AbstractHigh‐Ni layered oxides undergo distinct chemomechanical evolution upon high‐voltage charging over 4.2 V, producing crystallographic defects and associated lattice distortions within the cathode particles. Due to the significant recovery of chemomechanical evolutions during discharging, lattice imperfections resulting from high‐voltage charging tend to remain hidden and pose challenges in their characterization at discharged states. Moreover, their impact on the structural stability and electrochemical performance of cathode materials remains elusive. In this study, synchrotron‐based X‐ray diffraction and Bragg coherent diffraction imaging (CDI) successfully detects subtle yet persistent lattice distortions in the discharged state after high‐voltage cycling. In situ Bragg CDI further reveals internal strain evolution within the particles upon mild heating, which can be correlated with hidden lattice imperfections and structural instability. Despite comparable strain distributions before heating, the particles cycled over 4.2 V show significant strain evolution and intraparticle domain deformation upon heating, whereas the particles cycled below 4.2 V release the internal strain and retain their shape. These results suggest that latent lattice imperfections formed during high‐voltage cycling can trigger detrimental microstructural degradation at high temperatures and critically deteriorate the structural stability of the high‐Ni layered oxide particles, thereby increasing the potential risk of degradation at elevated temperatures.

Sex Differences in Axonal Dynamic Responses Under Realistic Tension Using Finite Element Models.

Existing axonal finite element models do not consider sex morphological differences or the fidelity in dynamic input. To facilitate a systematic investigation into the micromechanics of diffuse axonal injury, we develop a parameterized modeling approach for automatic and efficient generation of sex-specific axonal models according to specified geometrical parameters. Baseline female and male axonal models in the corpus callosum with random microtubule (MT) gap configurations are generated for model calibration and evaluation. They are then used to simulate a realistic tensile loading consisting of both a loading and a recovery phase (to return to an initial undeformed state) generated from dynamic corpus callosum fiber strain in a real-world head impact simulation. We find that MT gaps and the dynamic recovery phase are both critical to successfully reproduce MT undulation as observed experimentally, which has not been reported before. This strengthens confidence in model dynamic responses. A statistical approach is further employed to aggregate axonal responses from a large sample of random MT gap configurations for both female and male axonal models (n = 10,000 each). We find that peak strains in MTs and the Ranvier node and associated neurofilament failures in female axons are substantially higher than those in male axons because there are fewer MTs in the former and also because of the random nature of MT gap locations. Despite limitations in various model assumptions as a result of limited experimental data currently available, these findings highlight the need to systematically characterize MT gap configurations and to ensure a realistic model input for axonal dynamic simulations. Finally, this study may offer fresh and improved insight into the biomechanical basis of sex differences in brain injury, and sets the stage for more systematic investigations at the microscale in the future, both numerically and experimentally.

Fibrous mats based skin sensor with ultra-sensitivity and anti-overshooting dynamic stability enhanced with artificial intelligence

Next generation epidermal and wearable strain sensors are rapidly emerged as promising candidates for personalized medicine, soft machines, and human–machine interfaces. However, overshooting issues of these flexible strain sensors are major concerns during their dynamic strain monitoring, which often cause signal distortion and non-monotonic sensing characteristics. In addition, achieving a high sensitivtiy of these strain sensors within a full-body motion strain range (0–200%) remains a critical challenge. Herein, a conductive electrospun fibrous mats which are consisted of graphene anchored into fibrous thermoplastic polyurethane is proposed to endow strain sensors with anti-overshooting performance (or a good dynamic stability) and high sensitivity within full-body motion monitoring range. An overshooting-to-stable transition for the sensor’s electrical performance is observed by controlling the contents of conductive agents and substrate, which is elucidated by the kinetic changing behaviors of conductive pathways along the longitudinal and transverse strain directions. By strengthening the interaction forces between fillers and matrix, the conduction pathways are capable of rapidly switching to disconnection in response to external strains, thus achieving an ultrahigh sensitivity. The developed skin sensing platform is capable of detecting full range physiological signals and achieving healthcare Internet of Things in achilles tendon rehabilitation. Furthermore, a wearable Morse code-to-speech translation system powered with deep learning algorithm was demonstrated, with high recognition accuracy (>98.5%) and fast response time (∼16 ms).

High hemodynamic stresses induce aneurysms at internal carotid artery bends

To investigate the role of hemodynamic stresses in initiating cerebral aneurysms at bends of internal carotid artery (ICA). Sixty-one patients with 68 aneurysms at ICA bends were retrospectively enrolled as the experiment group. Among the 61 patients, 30 normal ICAs without aneurysms were chosen as the control. All patients had 3-dimensional angiography and CFD analysis. The bending angle was significantly (P < .0001) smaller in the experiment than control group (131.2º ± 14.9º vs 150.3º ± 9.5º). The dynamic pressure, shear stress, vorticity magnitude and strain rate were the least at direct flow impinging center where the total pressure was very high. The dynamic stress, shear stress, strain rate and gradients of total pressure except for gradient 1 were significantly (P < .05) greater at the aneurysm site than at all the other sites. The total pressure at the aneurysm site was greater (P < .05) than at 1 lateral location and at the distal area but smaller (P < .05) than at the proximal area. The dynamic pressure, shear stress, strain rate and gradient of total pressure at the aneurysm site were significantly (P < .001) greater than on the aneurysm dome. The hemodynamic stresses were all significantly (P < .01) greater at the aneurysm site in the experiment group than at the site corresponding to the aneurysm in the control group. Aneurysms at the ICA bends are caused by direct flow impingement and increased hemodynamic stresses, and smaller arterial bending angles result in abnormally enhanced hemodynamic stresses to initiate an aneurysm near the flow impingement area.

Dynamic lung aeration and strain with positive end-expiratory pressure individualized to maximal compliance versus ARDSNet low-stretch strategy: a study in a surfactant depletion model of lung injury

BackgroundPositive end-expiratory pressure (PEEP) individualized to a maximal respiratory system compliance directly implies minimal driving pressures with potential outcome benefits, yet, raises concerns on static and dynamic overinflation, strain and cyclic recruitment. Detailed accurate assessment and understanding of these has been hampered by methodological limitations. We aimed to investigate the effects of a maximal compliance-guided PEEP strategy on dynamic lung aeration, strain and tidal recruitment using current four-dimensional computed tomography (CT) techniques and analytical methods of tissue deformation in a surfactant depletion experimental model of acute respiratory distress syndrome (ARDS).MethodsARDS was induced by saline lung lavage in anesthetized and mechanically ventilated healthy sheep (n = 6). Animals were ventilated in a random sequence with: (1) ARDSNet low-stretch protocol; (2) maximal compliance PEEP strategy. Lung aeration, strain and tidal recruitment were acquired with whole-lung respiratory-gated high-resolution CT and quantified using registration-based techniques.ResultsRelative to the ARDSNet low-stretch protocol, the maximal compliance PEEP strategy resulted in: (1) improved dynamic whole-lung aeration at end-expiration (0.456 ± 0.064 vs. 0.377 ± 0.101, P = 0.019) and end-inspiration (0.514 ± 0.079 vs. 0.446 ± 0.083, P = 0.012) with reduced non-aerated and increased normally-aerated lung mass without associated hyperinflation; (2) decreased aeration heterogeneity at end-expiration (coefficient of variation: 0.498 ± 0.078 vs. 0.711 ± 0.207, P = 0.025) and end-inspiration (0.419 ± 0.135 vs. 0.580 ± 0.108, P = 0.014) with higher aeration in dorsal regions; (3) tidal aeration with larger inspiratory increases in normally-aerated and decreases in poorly-aerated areas, and negligible in hyperinflated lung (Aeration × Strategy: P = 0.026); (4) reduced tidal strains in lung regions with normal-aeration (Aeration × Strategy: P = 0.047) and improved regional distributions with lower tidal strains in middle and ventral lung (Region-of-interest [ROI] × Strategy: P < 0.001); and (5) less tidal recruitment in middle and dorsal lung (ROI × Strategy: P = 0.044) directly related to whole-lung tidal strain (r = 0.751, P = 0.007).ConclusionsIn well-recruitable ARDS models, a maximal compliance PEEP strategy improved end-expiratory/inspiratory whole-lung aeration and its homogeneity without overinflation. It further reduced dynamic strain in middle-ventral regions and tidal recruitment in middle-dorsal areas. These findings suggest the maximal compliance strategy minimizing whole-lung dynamically quantified mechanisms of ventilator-induced lung injury with less cyclic recruitment and no additional overinflation in large heterogeneously expanded and recruitable lungs.

A Comparative Study on the Dynamic Tensile Strength Evaluation Method of Rock Materials

The representative calculation methods of dynamic tensile strength applied to the spalling test are comparatively reviewed in the same experimental cases. The results are compared with those of the ISRM suggested dynamic BD method. Through comparative verification results and analysis of methodological characteristics of each determination method in the spalling test, the most reasonable method for calculating dynamic tensile strength in the high strain rate condition is derived. The local strain rate and apparent strain rate are calculated for the same experimental cases, and the difference in the result values according to the strain rate calculation technique is analyzed through comparative verification of the calculated results. Consequently, the characteristics of each dynamic tensile strength determination method and strain rate calculation method in the spalling test are presented, and the results of the review on the most suitable method for calculating the dynamic tensile strength of rock materials are presented.

Analysis of dynamic strain aging in titanium alloys using CPFEM

Titanium alloys have been reported to exhibit Dynamic Strain Aging (DSA) at intermediate temperatures that strongly influence their workability and performance under various loading conditions. It has been experimentally well established that DSA in these alloys is due to the dislocation pinning and unpinning by the Cottrell atmosphere. In the present work, a model for DSA is developed which is an extension of Kubin–Estrin–McCormick (KEMC) model. The model takes into account the reduction in material strength due to thermal softening along with its implications on DSA. The one-dimensional DSA model developed in this work is further extended to the CPFEM framework. The results from this model show good agreement with the experimental findings for a wide range of temperatures.

Verification of Optical Fiber Multiparameter Sensing Technology for High Temperature Environment

Aiming at the measurement problems such as strain in high temperature environment, this paper builds an optical fiber sensor that is suitable for high temperature environment. A test system platform that can provide a high temperature environment of 1000 °C both dynamic and static strain loading is designed. The platform includes a high-temperature furnace, constant-strength beams and excitation devices. Based on the test system platform, the thermal strain and loading strain tests of the high temperature fiber optic sensor are completed.

Mechanical properties of refractory HEA WNbTaV and its penetration behavior to aluminum alloy plate

Quasi-static and dynamic compression experiments were conducted on WNbTaV to investigate its mechanical characteristics and its penetration behavior into an aluminum alloy target plate. Additionally, ballistic experiments with WNbTaV projectiles against 2A12 aluminum alloy thin targets were performed. The results indicate that HEA WNbTaV at a strain rate of 10−3 s−1 has a fracture strength of 1340 MPa, a yield strength of around 980 MPa, and a fracture strain of less than 7%. However, its dynamic yield strength is almost twice its quasi-static yield strength, and its dynamic fracture strain is more than twice the quasi-static compression fracture strain.When striking a 2 mm thick 2A12 aluminum alloy target plate with a velocity less than 348.5 m/s, the HEA WNbTaV projectile remains stiff and undeformed. Its maximum velocity before entering the target plate is roughly 273 m/s. Furthermore, within a certain impact velocity range, the residual velocity, initial impact velocity, and ultimate penetration velocity of the HEA WNbTaV projectile penetrating the 2 mm thick 2A12 aluminum alloy target plate meet the following relationships. vr=v02−2.13vb2.

Recruitment-to-inflation ratio assessed through sequential end-expiratory lung volume measurement in acute respiratory distress syndrome.

Positive end-expiratory pressure (PEEP) benefits in acute respiratory distress syndrome (ARDS) are driven by lung dynamic strain reduction: this depends on the variable extent of alveolar recruitment. The recruitment-to-inflation (R/I) ratio estimates recruitability across a 10-cmH2O PEEP range through a simplified maneuver. Whether recruitability is uniform or not across this range is unknown. The hypotheses of this study are that R/I represents an accurate estimate of PEEP-induced changes in dynamic strain, but may show a non-uniform behaviour across the conventionally tested PEEP range (15-5 cmH2O). Twenty patients with moderate-to-severe COVID-19 ARDS underwent a decremental PEEP trial (PEEP 15-13-10-8-5 cmH2O). Respiratory mechanics and end-expiratory lung volume by nitrogen dilution were measured the end of each step. Gas exchange, recruited volume, R/I, changes in dynamic, static and total strain were computed between 15 and 5 cmH2O (global R/I) and within narrower PEEP ranges (granular R/I). Between 15 and 5 cmH2O, median [Interquartile range] global R/I was 1.27 [0.40-1.69] and displayed a linear correlation with PEEP-induced dynamic strain reduction (r=-0.94, p<0.001). Intra-individual R/I variability within the narrower ranges was high (85% [70-109]). The relationship between granular R/I and PEEP was mathematically described by a non-linear, quadratic equation (r 2=0.96). Granular R/I across the narrower PEEP ranges had itself a linear correlation with PEEP-induced reduction in dynamic strain (r=-0.89, p<0.001). Both global and granular R/I well estimate PEEP-induced changes in lung dynamic strain. However, the effect of 10-cmH2O of PEEP on lung strain may be non-uniform. Granular R/I assessment within narrower PEEP ranges guided by end-expiratory lung volume measurement may aid more precise PEEP selection, especially when R/I obtained with the simplified maneuver between PEEP 15 and 5 cmH2O yields intermediate values, that are difficult to interpret for a proper choice between a high vs. low PEEP strategy.

Inverse PLC behavior of type A serration in Fe–18Mn-0.55C steel

In the present study, the behavior of type A serrations according to strain rate was investigated using the room-temperature tensile flow curves of Fe-18Mn-0.55C (wt%) steel specimens. In the strain rate range from 1 × 10−1 /s to 5 × 10−5 /s, a critical strain (ecA) of type A serrations was reduced with decreasing strain rate, indicating a normal Portevin-Le Chatelier (PLC) behavior. However, at the slow strain rates ranging from 5 × 10−5 /s to 1 × 10−6 /s, ecA was increased again with decreasing strain rate, although dynamic strain aging occurred just after yielding. This inverse PLC behavior of type A serrations was explained by applying the concept of the drag force (Fd) by the Cottrell atmosphere on aged dislocations to the existing mechanism of negative strain rate sensitivity. Fd was reduced with decreasing strain rate from 5 × 10−5 /s to 1 × 10−6 /s, suppressing the formation of the PLC band for type A serration.

Defect-induced inhomogeneous atomic environments in complex concentrated alloys

The multiple elements in equal ratios in complex concentrated alloys (CCAs) favor the formation of local atomic environments like segregation or chemical ordering observed in recent experiments. Such special local atomic environments may pin dislocations on the slip plane, resulting in a higher flow stress for the escape of dislocations and hence a dynamic strain aging (DSA) effect in the form of stress drop. Here, Monte Carlo molecular dynamics (MC/MD) simulations are used to elucidate the atomic atmospheres around dislocations and stacking faults in the NiCoCr alloy system and quantitatively determine the stress drop effect. Increased chemical ordering and segregation around stacking faults and dislocation cores are observed, but detailed analysis shows that atomic segregation around stacking faults (Suzuki atmospheres) contributes the most to stress drop, compared with segregation around dislocation cores (Cottrell atmospheres) and enhanced ordering (Fisher) effects. The MD simulated stress drops are in good agreement with theoretically predicted and experimental values. This work fills an important gap in the understanding of the DSA effect in H/MEAs.

Dynamic Strain Measurement of Rotor Blades in Helicopter Flight Using Fiber Bragg Grating Sensor.

Fiber Bragg grating (FBG) sensor has a lot of advantages over the resistance strain gauge and has been used in many applications. However, there are few applications of rotor blade dynamic measurement in helicopter flight. In this paper, a method for blade dynamic strain measurement using an FBG sensor in a helicopter's real flight is presented. The corresponding measurement system is established and can eliminate the effects of the helicopter's electromagnetic environment on the electrical sensing components in the measurement system with the orthogonal frequency-division multiplexing modulation. The measured dynamic strains on the rotor blades of the helicopter in real flight contain six harmonic frequencies with the vibration characteristics of rotor blades, indicating that the established FBG measurement method and system have practical engineering applications.

On the normal and inverse Portevin–Le Chatelier behavior in hot rolled Inconel 617 superalloy

In the present study the effect of hot rolling process on the normal and inverse Portevin-Le Chatelier behavior was investigated. The hot rolling process was carried out at 950 °C, 1050 °C, and 1150 °C to capture the effect of thermomechanical process on elimination or postponing of dynamic strain aging phenomenon in Inconel 617 during subsequent deformation process. The tensile test was performed within the temperature range between 350 °C and 750 °C at a constant strain rate. The microstructure evaluations were carried out by optical microscope and scanning electron microscope. The serrated flow was observed in the stress-strain curves at specific temperatures. The type of serrations changed from type B to type C at the strain rate of 5 × 10−4 s−1 as the tensile test temperature was enhanced. The change of normal PLC effect to the inverse PLC effect was intensified when the hot rolling temperature was increased; Hence, the inverse PLC effect was observed at 750 °C in the sample which had rolled at 1150 °C. Whilst the serrated flow was not seen at 750 °C in the samples which had rolled at 950 °C and 1050 °C. The critical strain, for the initiation of the serrated flow was found to reduce with the increasing temperature of hot rolling from 950 °C to 1150 °C. After tensile test, the microstructural evaluations revealed the proven substantial role of precipitation of γ′ and the Cr-rich M23C6 carbides in pinning of the mobile dislocations, which led to the inverse PLC effect.

System identification of excited beam immersed in granular materials: A multifrequency data-based method in a variational framework

Granules and immersed structures coupling vibration systems are common in civil, pharmaceutical, mining, and metallurgical fields. These systems present frequency-dependent physical parameters and nonlinear dynamic characteristics owing to the multiphase, cross-scaled, and highly nonlinear discrete media. The research on such coupling vibration systems has just started in recent years, mainly focusing on simulations and experiments, and the theoretical model has not been publicly reported. In order to obtain the general form of the dynamic equation of the granules and immersed beam coupling vibration systems, in this paper, the integral variational equation of the granules-beam system was first constructed based on the variational principle. A deflection curve reconstruction method was introduced to obtain the flexural function of the beam through data captured by a few strain measuring points. Furthermore, the coupling mechanism between the mass and stiffness data of the system with single-frequency responses was explained under an integral variational framework, and a multifrequency data-based method was proposed to identify the granules and immersed beam coupling vibration system. Numerical studies were conducted on the effectiveness and robustness of the proposed method, including the measurement noise and number of strain measuring points. Experimental studies on the granules and immersed beam coupling vibration system were based on dynamic strain testing techniques. The identification results further verified the feasibility of the proposed method, and the general form of the dynamic equation of the system and variations in the system parameters with excitation frequencies were obtained. The frequency-dependent characteristics generated new peak and jump phenomena, respectively, below and slightly above the first-order natural frequency of the beam.

Static pressure and dynamic impact characteristics of filled jointed rock after frozen-thaw cycle damage

In the construction project, rock mass is often destroyed from the joint plane, and the jointed rock mass is easy to be eroded by freeze-thaw environment. Therefore, the damage mechanical properties of filled jointed rock mass under freeze-thaw action are very important for construction disaster prevention, engineering safety evaluation and reinforcement. In order to research the effect of the freeze-thaw cycle on the mechanical deterioration properties and damage characteristics of filled jointed rocks, prefabricated filled jointed rock samples are tested with different numbers of freeze-thaw cycles under the temperature range of -20°C~20°C. Then the wave velocity test, static compression test and SHPB impact test are conducted on the rock samples after freeze-thaw. Based on the test results, the change regularity of wave velocity degradation, static compression mechanical properties and dynamic compression mechanical properties of filled jointed rocks under the effect of freeze-thaw cycles were analyzed. The results show that the wave velocity, static compressive strength and dynamic compressive strength of the filled jointed rocks all show a downtrend with the increase of the number of freeze-thaw cycles, and each parameter is positively correlated with the strength of the filling materials. Among them, the decrease in the wave velocity of the rock sample after 30 freeze-thaw cycles is greater than 30%, and the strength loss of the static peak compressive strength exceeds half of its initial strength. The static peak strain rises exponentially with the increase of the number of freeze-thaw cycles while the dynamic peak strain does not show a clear trend. The dynamic peak strain is about 1/10 to 1/5 of the static peak strain. Under the same freeze-thaw action, the lower the strength of filling material, the more serious the damage.

Dynamic mechanical properties of veined rocks under biaxial confinement

As the global demand for minerals continues to rise, mining operations deepen, and major risks arise from extreme geomechanical conditions. One risk of major concern is strainburst, a complex event characterized by the spontaneous release of energy at the limits of excavations triggered by dynamic disturbances such as blasting and induced seismicity. To study this phenomenon, we ran coupled static-dynamic tests performed under uniaxial and biaxial confinement in a Triaxial Hopkinson bar system. We used veined-rock samples from one of the largest underground mines in the world: El Teniente (Chile). Additionally, a high-speed camera was employed to study the role of dynamic loads and high strain rates (10-102 s−1) on the fracture pattern propagation. Our results show an increase in elastic modulus after increasing σ2 pre-stress. Two types of post-peak curves: I and II, were identified. While type I is related to fractures for which the sample does not lose the load capacity in a biaxial confinement state, type II is associated with the fragmentation and expulsion of fragments from the free faces of the tested samples. In addition, we observed that fracture propagation is controlled by veinlets that exhibit a favorable orientation in relation to the direction of the dynamic load. Moreover, two rockburst-related phenomena are observed: slab buckling, and rapid fragment ejection. Our findings suggest that fracture propagation occurs through the rock matrix when the mechanical properties exhibit a strong dependence on the strain rate. When this dependence is less evident, they are restricted to the veinlets. If a dynamic pulse generates deformation rates between 10 to 102 s−1, stiffness increases, and therefore energy dissipation increases as well. When combined with the predisposition of veined rocks to form blocks, these conditions create favorable environments for strainburst occurrences and may exacerbate the severity of this phenomenon in underground excavations.