Effect Of Dynamic Loading Research Articles

Studying the Effects of Mechanical Loads and Environmental Conditions on the Drive-Axle Performance

The paper discusses the problem of achieving the required output parameters of a truck drive under various operating conditions. The authors enumerate the final-drive and differential mechanical efficiency, the pre-load torque in the final-drive bearing assembly, the friction coefficient, and the differential locking factor as the most significant technical parameters of the drive axle and its components. The main factors that affect these parameters during operation are: (i) mechanical loads that transmission is exposed to when transmitting the torque from the engine to the drive wheels; (ii) the effects of external thermal and dynamic loads when driving on an uneven surface or in cold / hot climates. The paper describes the main dependences between the final-drive processes and the inter-wheel differential processes; it also demonstrates how the aforementioned factors affect the output parameters of the component. The assumptions hereof are based on the results of bench and field truck tests, including adverse-climate tests. We herein propose a method for estimating the drive-axle load, which is based on the weighted values of the aforementioned factors. We prove it feasible to use auto-adjusted heating of the drive-axle components. The degree of thermal exposure shall be determined with due account of environmental conditions, surface conditions, engine and transmission parameters. The control algorithm is supposed to automatically take into account any change in one or more factors. This approach to controlling the output parameters helps improve the efficiency and the longevity of the drive axle and truck as a whole.

Pressure of Soil on Cellular Structures of Hydraulic Constructions Produced by Dynamic Impacts

The basic types of soil pressures on the walls of cellular hydraulic structures under the effect of dynamic loads obtained in experiments are considered. It is shown that the greatest of these pressures (up to 1.7 times the static pressure) may arise from redistribution of loads from the aggregate between the walls and the foundation. A formula for determining this pressure is proposed.

Analytical and numerical investigations of dynamic crack propagation in brittle rocks under mixed mode loading

Determination of dynamic fracture parameters of brittle rocks is of particular importance in assessing rock structure stability, rock strength and rock behavior under the effect of dynamic loading. Major dynamic fracture parameters including initial crack extension angle, stress intensity factors, fracture toughness and crack propagation path are directly affected by crack propagation speed (CPS). In this study, the dynamic form of the maximum tangential stress criterion (DMTS-Criterion) was used to determine the fracture parameters as a function of CPS under three loading conditions: 1) pure mode I, 2) pure mode II, and 3) mixed mode I-II. In addition, a dynamic two-dimensional crack propagation code (DTDCPC) was developed using the DDM to predict the crack trajectory in cracked semi-circular bend (SCB) specimens for different CPS values. CPS ranged from zero (the fully static case) to the Rayleigh wave speed (the fully dynamic case). The results showed that all fracture parameters increased by increasing CPS. In addition, under pure mode I, cracks only grew at acute angles (forward branching) and bifurcated when the CPS exceeded a critical value. Under mixed mode loading I-II and pure mode II, cracks grew at acute (forward branching) and obtuse (backward branching) angles. The backward branching of faults under pure mode II occurred in most rock types when crack propagation speed was greater than 0.81 of the Rayleigh wave speed. In addition, it was found that fracture toughness of pure mode II (KIIC), compared to that of pure mode I (KIC), decreased by increasing CPS to 0.76 of the Rayleigh wave speed, and cracks tended to grow under pure mode II. For high CPS, KIC was greater than KIIC, and cracks tended to grow under pure mode I. DTDCPC showed that the crack propagation path predicted in SCB-specimens deviated away from its original plane as CPS was increased, and the deviation of the crack propagation path decreased as the crack inclination angle increased.

Analysis of combined action of seismic loads and alkali-silica reaction in concrete dams considering the key chemical-physical-mechanical factors and fluid-structure interaction

This paper presents the results of the numerical analysis of concrete dam structures which are affected by Alkali Silica Reaction (ASR) and subjected to seismic load. In this research a Chemo-Thermo-Mechanical ASR Finite Element numerical code is developed to model and analyse this phenomenon in concrete dams. It considers the effects of variables such as temperature, non-uniform time-dependent material degradation and 3D stress confinement on ASR evolution. The model is validated by modelling the mechanical response of the Fontana gravity dam and comparing the results with the actual data on macro crack appearance and crest displacement. While the structural behaviour of ASR affected structures under monotonic and quasi-static loading has been extensively investigated over the last decades, limited research has addressed the effect of dynamic loads on structures affected by ASR. The combined effect of old and new cracks under dynamic excitation may cause dam failure. The numerical simulations are used to assess and predict the dynamic stability of the Koyna dam considering fluid-structure interaction and are also used to investigate the evolution of damage associated with inception and development of macro cracks in the dam structure due to the combined effect of the synthetic ASR and realistic seismic loading on the dam. The results show that this combined action can significantly change the dynamic behaviour of typical concrete dams due to concrete material degradation and crack development.

Fault Diagnosis of Dynamically Loaded Bearing with Localized Defect Based on Defect-Induced Excitation

The defect-induced excitations causing the bearing to vibrate have significant contribution in vibration generated from rolling element bearings. Therefore, in this work an investigation has been made to estimate the excitations caused by localized defects on different elements of a bearing, viz., inner race, rolling element and outer race, subjected to load. The applied load on a radially loaded bearing is often not of pure static nature but has a dynamic component associated with it. The dynamic load on bearing has been considered to be composed of a static and a dynamic component. The dynamic component has been considered to be either harmonic or random in nature. The spectra of excitations have been obtained to correlate with the significant spectral components of respective response. The amplitudes of harmonic and variance of random loading have been varied to investigate the effects of dynamic loading on excitation spectra. Numerical results have been obtained for NJ305 bearing with normal clearance. For harmonic load, a new spectral component has been noticed in frequency spectrum of excitation for the defects on outer race and rolling element, whereas there is no new component for inner race defect. In the case of random loading, noise in the spectrum has been noticed. The rise in noise level and coefficients of spectral components also perceived with the increase in variance of random load. The rise in noise level with increment in dispersion of random loading is significant so that few spectral components have been masked under the noise for non-stationary defect, whereas for stationary defect the spectral components are clearly detected in spite of rise in noise level. The numerical procedure explained can be extended for different kinds of loading which may be due to the defects in mating components supported by shaft and bearing system.

A Mathematical Model to Evaluate the Impact of the Maintenance Strategy on the Service Life of Flexible Pavements

The structural failure of a flexible pavement occurs when the accumulated fatigue damage produced by all the vehicles that have passed over each section exceeds a certain threshold. For this reason, the service life of pavement can be predicted in terms of the damage caused by the passage of a single standard axle and the expected evolution of traffic intensity (measured in equivalent standard axles) over time. In turn, the damage caused by the passage of an axle depends on the vertical load exerted by the wheels on the pavement surface, as given by the technical standard in application, and the depths and mechanical characteristics of the layers that compose the pavement section. In all standards currently in application, the unevenness of the road surface is disregarded. Therefore, no dynamic effects are taken into consideration and the vertical load is simply given in terms of the static weight carried by the standard axle. However, it is obvious that the road profile deteriorates over time, and it has been shown that the increase in the pavement roughness, when considered, gives rise to important dynamic effects that may lead to a dramatic fall in the expected structural service life. In this paper, we present a mathematical formulation for the fatigue analysis of flexible pavements that includes the effects of dynamic axle loading. A pavement deterioration model simulates the sustained growth of the IRI (International Roughness Index) over time. Time is discretized in successive time steps. For each time step, a road surface generation model provides a profile that renders the adequate value of the IRI. A QHV (Quarter Heavy Vehicle) model provides the dynamic amplification function for the loads exerted on the road surface along a virtual ride. This function is conveniently averaged, what gives the value of the so-called effective dynamic load amplification factor (DLA); this is the ratio between the effective dynamic loading and the static loading at each time step. Finally, the damage caused by the passage of the standard axle can be evaluated in terms of the dynamic loading. The product of this damage times the number of equivalent standard axles gives the total fatigue damage produced in the time step. The accumulated fatigue damage at each moment is easily computed by just adding up the damage produced in all the previous time steps. The formulation has been implemented in the software DMSA (Dynamic & Maintenance Simulation App). This tool has been specifically developed for the evaluation of projects in applications for financing submitted to the European Investment Bank (EIB). DMSA allows for quantifying the expected structural service life of the pavement taking into account both the rise of the dynamic axle loads exerted by the traffic as the road profile deteriorates over time and the different preventive maintenance strategies to be taken into consideration.

Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration

Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

Experimental Study on Behavior of Bench-Scale Steel Structure Retrofitted with CFRP Composites under Ambient Vibration

Usage of FRP composites for the retrofitting purpose of the structures against the harmful effect of dynamic loads are gaining popularity, it is used in a wide variety of disciplines including civil engineering. Thus, there is a great need to study the behavior of FRP composites for strengthening purposes of structures using empirical methods. In this study, a bench-scale steel structure model was strengthened with CFRP composite and tested using operational modal analysis. To conduct operational modal analysis a bench-scale earthquake simulator and ambient vibration emulator were used. Same steel structure model was tested without strengthening procedure. Obtained dynamic responses (maximum-minimum displacements and accelerations before and after application of CFRP) of steel structure model have compared to each other. This study shows that floor displacements of the model have been decreased along the height of the structure up to 41.43 %. Therefore, the results of the experiment confirm the effectiveness CFRP composites for the strengthening of steel structures.

The effects of dynamic compressive loading on human mesenchymal stem cell osteogenesis in the stiff layer of a bilayer hydrogel.

Bilayer hydrogels with a soft cartilage-like layer and a stiff bone-like layer embedded with human mesenchymal stem cells (hMSCs) are promising for osteochondral tissue engineering. The goals of this work were to evaluate the effects of dynamic compressive loading (2.5% applied strain, 1Hz) on osteogenesis in the stiff layer and spatially map local mechanical responses (strain, stress, hydrostatic pressure, and fluid velocity). A bilayer hydrogel was fabricated from soft (24kPa) and stiff (124kPa) poly (ethylene glycol) hydrogels. With hMSCs embedded in the stiff layer, osteogenesis was delayed under loading evident by lower OSX and OPN expressions, alkaline phosphatase activity, and collagen content. At Day 28, mineral deposits were present throughout the stiff layer without loading but localized centrally and near the interface under loading. Local strains mapped by particle tracking showed substantial equivalent strain (~1.5%) transferring to the stiff layer. When hMSCs were cultured in stiff single-layer hydrogels subjected to similar strains, mineralization was inhibited. Finite element analysis revealed that hydrostatic pressures ≥~600Pa correlated to regions lacking mineralization in both hydrogels. Fluid velocities were low (~1-10nm/s) in the hydrogels with no apparent correlation to mineralization. Mineralization was recovered by inhibiting ERK1/2, indicating cell-mediated inhibition. These findings suggest that high strains (~1.5%) combined with higher hydrostatic pressures negatively impact osteogenesis, but in a manner that depends on the magnitude of each mechanical response. This work highlights the importance of local mechanical responses in mediating osteogenesis of hMSCs in bilayer hydrogels being studied for osteochondral tissue engineering.

INVESTIGATION OF FEATURES OF DUAL WEAR OF PADS IN BRAKE SYSTEM OF FREIGHT CARS

Purpose. This research is aimed at revealing features of dual wear of pads in the brake system of freight cars. Methodology. The complex of theoretical and operational research concerning the causes and consequences of dual wear of pads, as the most widespread one in the freight cars, was conducted. Using the theory of planning the experiment based on the collected statistical material an adapted mathematical modeling of the dual wear process was performed and negative factors were determined. The Mathcad software and STATISTIKA software application were used. Findings. A comparative analysis of various devices for the uniform wear of brake pads showed insufficient efficiency. It has been established that typical devices of uniform wear of brake shoes (up to 95%) are in damaged condition due to the effect of significant dynamic loads. Therefore, the shoes are bent, pressed with their upper edges to the wheel threads and when driving in trains without braking do harmful friction with the formation of double frictional wear of the working body of the shoes. It has been theoretically proved that in a hinged connection of a vertical lever with a brake beam king post a harmfully acting torque from the gravitational forces is formed, which becomes the main cause of the dual wear of the brake shoes. Kinetostatic analysis, taking into account the dynamic forces in the unsprung parts of the bogie, has allowed establishing the cause of dual wear and determining the possibility of eliminating the specified torque in the existing brake system. According to the R & D and the Ukrzaliznytsia`s order the operational tests on 10 gondola cars constructed by Kriukiv Railway Car Building Works were performed. They confirmed the results of the theoretical studies. Originality. For the first time, it was discovered, the research was initiated and the definition – the dual deterioration of brake pads was proposed. A mathematical regression model was developed for determining the main cause of dual wear of pads in a typical mechanical braking system of three-element bogies. It was adapted the mathematical approach to the planning of experiments with the construction of the corresponding schemes-models, which revealed the malignant moment of forces, bending the break beam on the pendulum suspensions until the upper edges of the brake pads will be pressed to the wheel thread. Practical value. The results of the research can be used in the design, modernization and operation of brake systems for both the operational fleet, as well as a new generation of three-element bogies.

Numerical Simulation of Dynamic Analysis of Glacier Under Seismic Loading Based on Combined Finite-Discrete Method

The dynamic analysis of the Laohugou No.12 Glacier of Qilian Mountain under given seismic loading effect is analyzed by using combined finite-discrete element method (FDEM). The necessary ice parameters for FDEM simulation are calibrated by using numerical experiments of biaxial compression corresponding to the physico-mechanical parameters. The results indicated that the stress-strain curves are strain softening, and the peak value of deviatoric stress is consistent with the laboratory experiments. Under the dynamic load effect, the glacier slip along the slope direction, and the whipping effect of the speed is obvious. The feasibility of using FDEM method to study discontinuous problems such as ice avalanche is discussed.

Metallic ion doped tri-calcium phosphate ceramics: Effect of dynamic loading on in vivo bone regeneration

The present study was carried out to evaluate the effect of dynamic loading on bone regeneration performance of different doped β-tri-calcium phosphate ceramics. We have developed porous beta tri-calcium phosphate (β-TCP), 5%zinc doped, 5% magnesium doped and 5% titanium doped β-TCP by aqueous solution combustion technique. All the synthesized β-TCP powders showed pore size of 21–146 μm (pure β-TCP), 16–142 μm (Zn-β-TCP), 28–156 μm (Mg- β-TCP) and 14–173 μm (Ti-β-TCP) while their apparent porosity 17.89%, 28.09%, 26.54% and 25.87% respectively. The pure and doped samples were implanted in femoral bone defect model (rabbit) to assess bone regeneration under dynamic loading. Bone regeneration was assessed after 1 and 2 month post-implantation on the basis of clinical radiological, histological, fluorochrome labelling, micro computed tomography (μ-CT) and scanning electron microscopy (SEM). Radiological and fluorochrome labelling study showed reduced size of 5%Ti-β-TCPimplant vis-à-vis more new bone formation as compared to other groups. Micro-CT of the implanted bone sample showed a significant amount of newly formed bony tissue surrounding the Ti-β-TCP implant as compared to other samples. Similar findings of less interfacial gap between the implant and bone were also observed in SEM study. However, all the doped materials are suitable as bone grafting material and have potential for application in bone tissue engineering.

Effect of dynamic and static loading during in vitro degradation of a braided composite bioresorbable cardiovascular stent

Bioresorbable cardiovascular stents are usually subjected to dynamic mechanical loads in vivo, which results in a different degradation profile compared to that measured under a static in vitro immersion test. In this study, a dynamic test platform was used to mimic cyclic pulsatile pressure and compared the changes in polymer properties of poly(p-dioxaone)/polycaprolane (PPDO/PCL) braided composite bioresorbable stents (BCBRSs) with static loading and non-loaded environments. The results showed static compressive load accelerated the changes in the hydrolysis process and crystallinity for polymers while the pulsatile pressure increased surface corrosion of the stent struts. Moreover, the degradation rate under dynamic loading was attenuated due to the mitigation of viscous flow of molecule chains and autocatalysis process, compared with that under static loading and non-loaded conditions.

Fleetwide data-enabled reliability improvement of wind turbines

Wind farms are an indispensable driver toward renewable and nonpolluting energy resources. However, as ideal sites are limited, placement in remote and challenging locations results in higher logistics costs and lower average wind speeds. Therefore, it is critical to increase the reliability of the turbines to reduce maintenance costs. Robust implementation requires a thorough understanding of the loads subject to the turbine's control. Yet, such dynamically changing multidimensional loads are uncommon with other machinery, and generally underresearched. Therefore, a multitiered approach is proposed to investigate the load spectrum occurring in wind farms. Our approach relies on both fundamental research using controllable test rigs, as well as analyses of real-world loading conditions in high-frequency supervisory control and data acquisition data. A method is introduced to detect operational zones in wind farm data and link them with load distributions. Additionally, while focused research further investigates the load spectrum, a method is proposed that continuously optimizes the farm's control protocols without the need to fully understand the loads that occur. A case of gearbox failure is investigated based on a vast body of past experiments and suspect loads are identified. Starting from this evidence on the cause and effects of dynamic loads, the potential of our methods is shown by analyzing real-world farm loading conditions on a steady-state case of wake and developing a preventive row-based control protocol for a case of cascading emergency brakes induced by a storm.

Experimental investigation of axially loaded reinforced concrete square column subjected to lateral low‐velocity impact loading

Design of reinforced concrete (RC) columns has been carried out under the effect of static loads and dynamic loads with long return period such as earthquake and wind. However, due to reasons such as the vehicle crash to the bridges of highway or seaway, rock fall, the collision of masses with the effect of flood and landslide, the effect of the blast‐induced air‐shock wave to buildings that have strategic importance, RC column may subject to sudden dynamic impact loads. For this reason, it is considered that the impact behavior of RC columns, which are highly important vertical load‐bearing members for the stability of structures, should be investigated and taken account of the design stage. For this purpose, an experimental study was performed. Sixteen RC square columns with the scale of 1/3 were manufactured and tested under impact load by using drop‐weight test setup that was specially designed by authors for impact tests of beam, column, and slab specimens. In the experimental study, the axial load level applied to RC column, input impact energy, and shear reinforcement ratio were taken as variables and with the effect of lateral impact energy applied to RC columns, time‐history of impact load acting on columns, the acceleration and the displacement values of columns were measured. The effect of experimental variables on the impact behavior of RC columns was determined and interpreted in detail. It has been demonstrated that axial load level, impact energy, and shear reinforcement ratio have a significant effect on the impact behavior of RC columns.

Tether analyses of offshore triceratops under ice force due to continuous crushing

Oil exploration and production in ultra-deep ice-infested waters demands an innovative structural form to withstand the ice loads. Offshore triceratops is one such new-generation innovative, compliant platforms, which show good adaptability in extreme sea state conditions even under the combined action of wind, waves, and current. As tethers are the crucial components in compliant platforms like a triceratops, it is of paramount importance to study the effect of dynamic ice loads on tether tension variation. The main aim of this study is to carry out the tether tension analysis under the ice force action in different ice sea states. The ice force time history is developed from the continuous crushing ice spectral model, and numerical studies are carried out using Ansys Aqwa by applying the ice force on buoyant legs. The study reveals that the tether tension variation is less than 10% even under extreme ice sea state. The parametric studies are also carried out to assess the effect of ice velocity, ice crushing strength, and ice thickness on tether tension variation. It is found that the maximum stress developed in the wires of tethers is very less compared to the yield stress of the material, ensuring no tether failure. However, a large number of stress cycles may lead to fatigue failure of tethers. Hence, fatigue analysis is also carried out to assess the fatigue damage and service life of tethers. The results show that fatigue damage increases from normal to extreme ice sea state. The results are also compared with open-water load case. Studies carried out under lock-in ice condition shows the increase in the fatigue damage and reduction in the service life of the tethers.

Effects of dynamic loading on fracture healing under different locking compression plate configurations: A finite element study

The design of patient specific weight-bearing exercises after the surgical implementation of internal fixations is of critical importance for bone fracture healing. The purpose of this study is to theoretically investigate the effects of physiologically relevant dynamic loading on early stage of fracture healing under different locking compression plate (LCP) configurations. The finite element results show that dynamic loading enhanced transport of bone cells and growth factors in the fracture callus is much dependent on the flexibility of LCP. In comparison to free diffusion, a relatively flexible LCP together with dynamic loading could significantly enhance solute transport in callus. For example, a flexible LCP achieved by increasing WL (Working Length) and BPD (Bone Plate Distance) (e.g. WL=100 mm and BPD=2 mm) together with a 5-h 150 N@1 Hz dynamic loading could increase the uptake of chondrocytes by around 280% compared to free diffusion, osteoblasts by around 180%, osteogenic growth factors by around 120% and chondrogenic growth factors by around 220%. In addition, dynamic loading enhanced transport of cells and growth factors under LCP is spatially dependent with a relatively higher enhancement in far cortex zone than that in near cortex zone. The outcomes from present study could potentially assist orthopaedic surgeons to determine optimal loading regimes with consideration of patient specific LCP configurations.

Seismic capacity and multi-mechanism analysis for dry-stack masonry arches subjected to hinge control

Masonry arches are vulnerable to seismic actions. Over the last few years, extensive research has been carried out to develop strategies and methods for their seismic assessment and strengthening. The application of constant horizontal accelerations to masonry arches is a well-known quasi-static method, which approximates dynamic loading effects and quantifies their stability, while tilting plane testing is a cheap and effective strategy for experimentation of arches made of dry-stack masonry. Also, the common strengthening techniques for masonry arches are mainly focusing on achieving full strength of the system rather than stability. Through experimentation of a dry-stack masonry arch it has been shown that the capacity of an arch can be increased, and the failure controlled by defining hinge positions through reinforcement. This paper utilizes experimentally obtained results to introduce: (1) static friction and resulting mechanisms; and (2) the post-minimum mechanism reinforcement requirements into the two-dimensional limit analysis-based kinematic collapse load calculator (KCLC) software designed for the static seismic analysis of dry-stack masonry arches. Computational results are validated against a series of experimental observations based on tilt plane tests and good agreement is obtained. Discrete element models to represent the masonry arch with different hinge configurations are also developed to establish a validation trifecta. The limiting mechanism to activate collapse of arches subjected to hinge control is investigated and insights into the optimal reinforcement to be installed in the arch are derived. It is envisaged that the current modelling approach can be used by engineers to understand stability under horizontal loads and develop strengthening criteria for masonry arches of their care.

J–R fracture toughness of cold-worked TP316L stainless steel under seismic loading conditions

This study conducted J–R fracture toughness tests on as-received and cold-worked TP316L stainless steels (SSs) under dynamic and cyclic loading conditions to investigate the effect of seismic loads on the fracture behaviour of age-degraded materials. Additionally, tensile tests were carried out to obtain the reference mechanical properties of both materials, and to evaluate the deformation behaviours under quasi-static and dynamic loads. Cold-worked (33%) TP316L SS was used in the test to simulate irradiation-hardened TP316L SS. The J–R fracture toughness tests were conducted under monotonic load with quasi-static and dynamic displacement rates, and under cyclic load with quasi-static displacement rate at room temperature and 316 °C. The results showed that the strength and fracture resistance of TP316L SS were considerably increased and reduced by 33% cold-working, respectively; the change in strength and fracture resistance was particularly notable at 316 °C. The dynamic loading effect on the deformation and fracture behaviours was negligible for both as-received and cold-worked TP316L SSs, regardless of test temperature. Cyclic loading considerably reduced the fracture resistance of the as-received TP316L SS, but the effect of cyclic loads on the fracture behaviours was insignificant for the cold-worked TP316L SS; in particular, the cyclic loading effect was negligible at 316 °C.

Experimental Study of the Dynamic Shear Response of Rocks Using a Modified Punch Shear Method

Cohesion and internal friction angle are the two material parameters used in the Coulomb model to predict rock failure in many rock engineering applications. Although these two parameters have been extensively quantified under static conditions using the direct shear or the triaxial compression methods, the effect of dynamic loading on these parameters is not yet clear. A dynamic punch shear method was proposed by Huang et al. (Rev Sci Instrum 82:053901. https://doi.org/10.1063/1.3585983 , 2011) to measure the dynamic cohesion of rocks, and the dependence of cohesion on the loading rate has been revealed. To further investigate the effect of dynamic loading on the internal friction angle and thus the complete dynamic shear response of rocks, this method is extended in this study to include the normal stress by applying lateral confinement to a disc specimen. The confinement is realized by enclosing the specimen assembly in a 1.5 inch diameter Hoek cell. The dynamic load is applied by a split Hopkinson pressure bar system, which is modified to ensure that the specimen assembly remains intact in the Hoek cell during pressurization by applying a static axial pre-stress. Three groups of green sandstone specimens under confinements of 0, 10 and 20 MPa are tested with different loading rates. The results show that the dynamic shear strength exhibits significant rate dependency and it thus increases with the loading rate and the normal stress. The dynamic cohesion increases with the loading rate, while the internal friction angle remains constant.