Instantaneous Load Research Articles

Effect of surface inclination on vertical loading rate and footstrike pattern in trail and road runners

Effect of surface inclination on vertical loading rate and footstrike pattern in trail and road runners

Semi‐analytical solutions for the consolidation of unsaturated composite ground with floating permeable columns under equal strain condition

AbstractThis study focuses on the mathematical interpretation and consolidation behavior of unsaturated composite ground with floating permeable columns (FPC). By combining the axisymmetric consolidation model with the equal strain assumption, the consolidation problem of unsaturated composite ground with FPC is transformed into a one‐dimensional consolidation problem of an equivalent double‐layer ground. The consolidation governing equations of the reinforced zone and the underlying stratum are derived respectively. The Laplace transformation and Gauss elimination method are used to obtain solutions for the average excess pore pressure and settlement in the Laplace transform domain. The semi‐analytical solutions for the consolidation of composite ground in the time domain are obtained by implementing the Crump numerical method for the inverse Laplace transformation. A comparison with the existing literature and numerical simulation results from Finite Element Methods (FEM) confirms the correctness of the proposed semi‐analytical solutions. Based on these solutions, the consolidation behavior of an unsaturated composite ground with FPC under instantaneous loading is investigated. The results indicate that the penetration ratio of the permeable column is the most significant factor affecting the consolidation of composite ground. Furthermore, the consolidation rate and settlement of the composite ground also highly depend on the unsaturated soil in the underlying stratum.

A two-layer energy management system for a hybrid electrical passenger ship with multi-PEM fuel cell stack

The hybrid combination of hydrogen fuel cells (FCs) and batteries has emerged as a promising solution for efficient and eco-friendly power supply in maritime applications. Yet, ensuring high-quality and cost-effective energy supply presents challenges. Addressing these goals requires effective coordination among multiple FC stacks, batteries, and cold-ironing. Although there has been previous work focusing it, the unique maritime load characteristics, variable cruise plans, and diverse fuel cell system architectures introduce additional complexities and therefore worth to be further studied. Motivated by it, a two-layer energy management system (EMS) is presented in this paper to enhance shipping fuel efficiency. The first layer of the EMS, executed offline, optimizes day-ahead power generation plans based on the vessel's next-day cruises. To further enhance the EMS's effectiveness in dynamic real-time situations, the second layer, conducted online, dynamically adjusts power splitting decisions based on the output from the first layer and instantaneous load information. This dual-layer approach optimally exploits the maritime environment and the fuel cell features. The presented method provides valuable utility in the development of control strategies for hybrid powertrains, thereby enabling the optimization of power generation plans and dynamic adjustment of power splitting decisions in response to load variations. Through comprehensive case studies, the effectiveness of the proposed EMS is evaluated, thereby showcasing its ability to improve system performance, enhance fuel efficiency (potential fuel savings of up to 28%), and support sustainable maritime operations.

Electrohydraulic proportional position and pressure loading control utilizing a state perception and processing method

A new multifunctional proportional control triaxial stress loading apparatus is presented in this study, which can apply an output force on coal rock to simulate the conditions of triaxial stress loading, aiming at solving the problems of excessive consideration of static indices in the design and the incompleteness of the simulation and test verification system for the test parts at the performance analysis stage. This apparatus mainly combines the configuration of a triaxial stress loading system which can meet the stress loading requirements under different operating conditions, with the effective integration of multiple pressure loading operations based on the electrohydraulic proportional control method. In this context, a pressure and position combined control strategy based on the sliding mode is proposed to control the vertical and longitudinal loading hydraulic cylinders. Then, a co-simulation mode including the triaxial stress loading hydraulic system is established to verify the control strategy, system response characteristics and selection of the controller parameters. Furthermore, a multifunctional stress loading experimental platform is developed, and the stress loading characteristics with the proposed strategy are tested and analyzed. The results show that the triaxial stress loading hydraulic system can meet the response characteristics, the fluctuating deviation of the constant loading test can be restricted to 8.5%, the tracking error of the variable loading test is small, the minimum response time of instantaneous loading can reach 2.8 s, and the stress loading effect is noticeable. The experimental platform fully indicates that the stress loading system with the state perception and processing method as the core can meet a variety of verification indices of constant, variable and instantaneous loading tests. This research provides technical support for the smooth, synchronous control and intelligent operation of various types of hydraulic actuator machines.

The gradual removal of Hertz pressure from the surface of elastic half-space

Contact stress determination in non-stationary dynamic loading of elastic bodies is crucial for modelling structures at high speeds, but it presents mathematical challenges due to the time-dependent and often unknown contact area size and shape. The study aims to obtain an energy remainder estimation that forms waves during the contact interaction of elastic bodies, based on the exact solutions of non-stationary problems for an elastic half-space. For this purpose, the problem of the instantaneous loading half-space as an additional research problem was reconstructed using the Hankel transform concerning a radial coordinate and the Laplace transform concerning a time variable. The method of derivation of the displacements at an elastic half-space loaded (unloaded) gradually by Hertz's contact pressure has been proposed. Its availability made it possible to pass to the solution of the main problem – the problem of gradual loading of the half-space surface by Hertz pressure. The possibility of changing of the order of differentiation and integration operations in the obtained representation is substantiated based on the integrand properties. The cases when the speed of the indenter was constant when its motion was uniformly accelerated and when the motion corresponded to the law of the first quarter of the cosine period in the time were considered. It was concluded that the distribution of dynamic contact stresses is similar to the Hertz distribution. An estimation of the part of the energy spent on the formation of elastic waves was made for various laws of unloading. The practical significance of this study lies in its development of an effective method for calculating normal displacements on a loading area in dynamic contact interactions of elastic bodies, which can be valuable for modelling structures at high speeds

A novel time-dependent damage constitutive model for hard rock materials

The mechanical behavior of deep hard rocks plays a crucial role in the long-term safety and stability of engineering structures. This work focuses on studying the instantaneous and time-dependent fracture propagation of hard rock materials from a theoretical perspective. A new unified constitutive model, based on a modified Mohr–Coulomb (M-C) criterion, is proposed to accurately represent the short and long-term mechanical properties of hard rocks. To capture the strain hardening and strain softening behaviors, damage is utilized as an internal mechanism-driven variable, controlling the expansion and contraction of the plastic yield surface. Additionally, a combination of time-dependent damage law and viscoplastic theory is employed to account for nonlinear creep deformation characteristics. By considering the time-dependent effects, the model can be applied to both instantaneous loading and creep conditions. The general algorithm format is derived in detail, and an explicit integration algorithm is utilized to update the time-dependent damage evolution. Finally, the proposed model is validated by comparing its predictions with the short and long-term mechanical responses of Beishan granite and Rumei dacite. This comprehensive constitutive model improves our understanding of continuum damage mechanics and provides a scientific basis for analyzing and evaluating the long-term safety and stability of deep hard rock engineering projects.

Association of tibial acceleration during walking to pain and impact loading in adults with knee osteoarthritis

BackgroundHigher impact loading during walking is implicated in the pathogenesis of knee osteoarthritis. Accelerometry enables the measurement of peak tibial acceleration outside the laboratory. We characterized the relations of peak tibial acceleration to knee pain and impact loading during walking in adults with knee osteoarthritis. MethodsAdults with knee osteoarthritis reported knee pain then walked at a self-selected speed on an instrumented treadmill for 3 min with an ankle-worn inertial measurement unit. Ground reaction forces and tibial acceleration data were sampled for 1 min. Vertical impact peaks, and average and peak instantaneous load rates were determined and averaged across 10 steps. Peak tibial acceleration was extracted for all steps and averaged. Pearson's correlations and multiple linear regression analyses assessed the relation of peak tibial acceleration to pain and impact loading metrics, independently and after controlling for gait speed and pain. FindingsHigher peak tibial acceleration was associated with worse knee pain (r = 0.39; p = 0.01), and higher vertical average (r = 0.40; p = 0.01) and instantaneous (r = 0.46; p = 0.004) load rates. After adjusting for gait speed and pain, peak tibial acceleration was a significant predictor of vertical average (R2 = 0.33; p = 0.003) and instantaneous (R2 = 0.28; p = 0.02) load rates, but not strongly associated with vertical impact peak. InterpretationsPeak tibial acceleration during walking is associated with knee pain and vertical load rates in those with knee osteoarthritis. Clinicians can easily access measures of peak tibial acceleration with wearable sensors equipped with accelerometers. Future work should determine the feasibility of improving patient outcomes by using peak tibial acceleration to inform clinical management.

Instantaneous dental implant loading technique by fixed dentures: A retrospective cohort study.

In the context of dental prostheses, splinting multiple implants together may improve their stability. The approach may be especially favorable when performing immediate loading procedures, increasing the implant osseointegration rate, and reducing the risk of implant and prosthetic failure. The instantaneous loading technique (ILT) involves creating a metal framework to splint the implants by intraorally welding them pair-by-pair, using purposefully created abutments. The aim of the study was to investigate the prosthetic success when using ILT to rehabilitate partially edentulous patients through immediately loaded prostheses. Clinical records of patients treated with ILT were retrospectively assessed, and the prosthetic success rate was analyzed in terms of fractures, chipping, unscrewing, screw fracture rate, and mucositis. Furthermore, the implant success rates were evaluated by measuring marginal bone loss (MBL). A total of 55 patients (20 males and 35 females with a mean age of 59.8 ±9.4 years), corresponding to 66 prostheses, were included. A total of 160 implants were placed. At the last follow-up (39.6 ±28.4 months), 1 patient (1.8%; 1 prosthesis (1.5%)) showed the fracture of the prosthesis material. Peri-implantitis affected 4 implants (2.5%), and 4 more implants (2.5%) showed radiolucency, affecting 5 patients (9.1%). Two other patients (3.6%) suffered from mucositis. The implant success rate, according to the Albrektsson and Zarb criteria, was 94.4%. No implants were lost. The mean MBL values at the implant level, the prosthesis level and the patient level were 0.28 ±0.56 mm, 0.30 ±0.51 mm and 0.33 ±0.54 mm, respectively. The instantaneous loading technique appears to be a viable approach to rehabilitating partially edentulous patients through immediate loading.

Molecular dynamics simulations of ultrasonic vibration-assisted grinding of polycrystalline iron: Nanoscale plastic deformation mechanism and microstructural evolution

Ultrasonic vibration-assisted grinding (UVAG) has attracted plenty of attention to significantly improve surface integrity. However, existing research has not systematically investigated the effect of vibration directions during UVAG at atomic and nanoscales, limiting our understanding of the plastic deformation mechanisms and microstructural evolution of ultra-precision machining. To address this issue, we proposed an MD model for multi-abrasive UVAG of polycrystalline iron considering various vibration directions. We comprehensively analyzed atomic flow fields, surface atom distributions, temperature fields, grinding forces, stress distributions, crystal orientations, and dislocation distributions. The simulation results demonstrate that UVAG effectively reduces grinding force and results in instantaneous grinding forces greater than conventional grinding (CG), and the instantaneous load impact phenomenon of radial vibration is more obvious. In surface morphology, axial vibration contributes to reducing surface roughness, while radial vibration is detrimental to surface smoothness. Microstructural evolution is mainly induced by stress. The primary plastic deformation mechanisms in UVAG of polycrystalline iron involve lattice rotation and dislocation mediation. Compared to axial vibration-assisted grinding (AVAG), radial vibration-assisted grinding (RVAG) and elliptical vibration-assisted grinding (EVAG) exhibit finer grain refinement, with RVAG leading to the highest dislocation density.

Hydrodynamics and Wake Flow Analysis of a Floating Twin-Rotor Horizontal Axis Tidal Current Turbine in Roll Motion

The study of hydrodynamic characteristics of floating double-rotor horizontal axis tidal current turbines (FDHATTs) is of great significance for the development of tidal current energy. In this paper, the effect of roll motion on a FDHATT is investigated using the Computational Fluid Dynamics (CFD) method. The analysis was conducted in the CFD software STAR-CCM+ using the Reynolds-averaged Navier–Stokes method. The effects of different roll periods and tip speed ratios on the power coefficient and thrust coefficient of FDHATT were studied, and then the changes in the vorticity field and velocity field of the turbine wake were analyzed by two-dimensional cross-section and Q criterion. The study indicates that roll motion results in a maximum decrease of 30.76% in the average power coefficient and introduces fluctuations in the instantaneous load. Furthermore, roll motion significantly accelerates the recovery of wake velocity. Different combinations of roll periods and tip speed ratios lead to varying degrees of wake velocity recovery. In the optimal combination, at a position 12 times the rotor diameter downstream, roll motion can recover the wake velocity to 92% of the incoming flow velocity. This represents a 23% improvement compared to the case with no roll motion.

Consolidation of multilayered soil with fractional derivative viscoelasticity due to surface loading and internal pumping

Classical Terzaghi’s solution provides a useful tool to predict the one-dimensional consolidation of homogeneous elastic soil layer with fully drained/undrained boundary condition under instantaneous loading. Due to the sedimentation process and complex internal structure, natural soils usually exhibit multilayered inhomogeneity and viscoelastic behavior. In practical cases, the drainage capacity of the boundaries can change with time. Thus, these practical factors should be well in considered for accurate prediction of the consolidation. This paper extends the classical Terzaghi’s solution to multilayered viscoelastic soil with continuous drainage boundaries and subjected to time dependent loading. The fractional derivative Kelvin-Voigt model is used to describe the viscoelasticity of soil. Two loading cases namely surface loading and internal pumping are considered. The consolidation problem is solved by Laplace transform technique and a transfer matrix formulation. Analytical solutions for excess pore water pressure, effective stress and settlement are given. The present solution is general and can reduce to existing solutions available in the literatures. Numerical studies are conducted to investigate the effects of viscoelastic parameters, boundary drainage capacity and loading rate on the consolidation behavior. It is shown that the multilayered soil system with large viscosity coefficient and small fractional order can consolidate fast. For the consolidation due to internal pumping, the drainage parameters have no influence on the consolidation process.

Exploration of trade-offs between NVH and efficiency in bevel gear design

Minimizing NVH and friction-induced power losses is becoming paramount in the design of geared transmissions. The aim of this paper is to present an automatic methodology to explore Pareto-optimal designs of bevel gears when minimization of noise and frictional losses is essential. In the first part, a semi-empirical model to estimate frictional power losses under elasto-hydrodynamic lubrication is described. The model has been validated against experimental data available in the literature in previous works by the authors. The efficiency calculation is coupled with a state-of-the-art loaded tooth contact analysis (LTCA) tool to obtain accurate predictions of the instantaneous load shared by the mating tooth pairs during the meshing cycle. In the second part, an automatic framework based on multi-objective optimization (MOO) is presented where the tooth micro-geometry is systematically designed. The design variables are represented by few coefficients of a polynomial basis that embodies the tooth flank ease-off topography. To ensure manufacturability, the polynomial modifications are projected onto the feasible set of the machine-tool envelopes. This step is achieved through a state-of-the-art identification algorithm that the authors have developed in previous work. Frictional losses are estimated with the aforementioned model, whereas the NVH level is measured by the loaded transmission error (LTE), directly available from the simulation tool. The maximum contact pressures are limited by the material properties, thus proper nonlinear constraints are prescribed. Application to a test case involving the design of a spiral bevel gearset reveals that the methodology presented allows the designer to obtain Pareto-optimal solutions in a systematic and automatic manner.

Modelling the Quench Behavior of an NI HTS Applied-Field Module for a Magnetoplasmadynamic Thruster Undergoing a 1kW Discharge

Recent advances in commercial miniaturised cryocoolers and high-temperature superconductors (HTS) have revived the discussion of using HTS electromagnets to enhance the thrust and efficiency of electric thrusters for space applications. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">An HTS applied-field magnetoplasmadynamic (AF-MPD) thruster is currently being developed. While the thruster is operating, there will be a large time-variable heat load on the cryogenic environment. The operation of a low-power cryocooler and energised HTS coils (operating at 70 K) adjacent to streams of hot plasma and large electrical discharges (on the order of 1 kW) represents a significant thermal management problem. The electromagnetic and thermal behaviour of non-insulated (NI) coils under these conditions, and how resilient they are to quenching during thruster operation, is not well understood. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">In this paper, a model is formulated to study the transient electromagnetic and thermal behaviour of an HTS-AF-MPD thruster with NI coils. The thruster and a conduction cooled cryogenic design are coupled via surface-to-surface radiation heat transfer. The model predicts current flow within the HTS, copper stabiliser and between turns, with the contact resistivity being a key input variable. Critical current is determined locally using temperature, magnetic field, and field angle in combination with a measured data set for a specific conductor. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">This model reveals conditions where the cryocooler can passively compensate for large instantaneous heat loads on the coils, demonstrating quench resistance.

Is the Actuator line method able to reproduce the interaction between closely-spaced Darrieus rotors? a critical assessment on wind and hydrokinetic turbines

The deployment of multiple closely-spaced Darrieus turbines has recently gained interest in the academic and industrial sectors due to their potential to increase power output and wake recovery. However, the computational cost of accurate three-dimensional, blade-resolved CFD analyses rapidly becomes unfeasible as long as multiple rotors are added, putting emphasis on the need for a more practical, yet accurate, simulation method. Based on recent assessments, the Actuator Line Method (ALM) has been shown to represent the most interesting solution for Darrieus turbines’ simulations. However, since the blade-flow interaction is not solved, no evidence was available to date on whether ALM can capture all the physical phenomena related to turbine mutual interaction.In this study, the reliability and limitations of the ALM in simulating closely-spaced Darrieus turbines were assessed using two pairs of turbines with varying geometrical and operational characteristics, focusing on turbine loads, local flow field, and wake development. The results demonstrate that the ALM is effective for simulating twin-rotor Darrieus turbines, particularly at medium and high tip-speed ratios, providing satisfactory predictions of instantaneous blade loads and capturing the increase in torque due to the mutual interaction between adjacent rotors. The ALM is also able to accurately reproduce the flow field across the twin rotors, as demonstrated through Proper Orthogonal Decomposition (POD) analysis of the wake flow field. With an average simulation time of 7 h/rev/core, compared to 508 h/rev/core for blade-resolved CFD, this study provides evidence that the ALM is a low-cost and reliable tool for simulating closely spaced Darrieus turbines, thus representing the most suitable tool to develop new VAWT applications like floating wind turbines or hydrokinetic installations.

STABILITY OF RODS WITH INITIAL IMPERFECTIONS IN THE FORM OF ECCENTRICITY OF LOAD APPLICATION UNDER LINEAR AND NON-LINEAR CREEP CONDITIONS

Stability of a compressed rod having initial imperfections in the form of eccentricity of applied load under conditions of linear and nonlinear creep is considered. It is noted that all real elements have some initial imperfections in the form of technological deflections, eccentricities of applied loads, etc., so they begin to bulge from the very beginning of loading. Another important factor in stability theory is the consideration of material creep. In this regard, the loading process is divided into two phases: the instantaneous loading process and the creep phase under constant external load. Moreover, creep can be time-limited or unrestricted. In the paper formulas for determination of critical forces of stability loss of the rod having initial imperfections, under short-term and long-term action of load are obtained. The equation allowing to determine time of the first crack appearance is derived. Derived are equations the roots of which are loads at action of which the first cracks appear at initial moment of time and at arbitrarily long period of load action. Analysis of acting force determining the character of rod deformation is executed. From the constructed stability equation it is possible to determine the critical force corresponding to the critical length of the section with cracks. For similar problems in nonlinear formulation formulas for determining critical force and critical displacement corresponding to maximum load are obtained. For the case of long duration load the equation which establishes relationship between load and displacement is obtained. Equation for determination of critical force under prolonged action of load has been derived. It has been established that critical displacement is the same under short- and continuous action of load. It is shown that at any intermediate moment critical displacement can be achieved under load lying in certain interval. Keywords: stability, rod, initial imperfection, eccentricity, linear creep, non-linear creep, critical force, crack, critical displacement.

Effects of defects on the transverse mechanical response of unidirectional fibre-reinforced polymers: DEM simulation and deep learning prediction

The presence of defects in composite materials is hardly avoidable during the process of materials manufacturing, which may affect the mechanical behaviour of the material. This paper presents a Representative Volume Element (RVE) based Discrete Element model (DEM) for analysing the effects of defects on the transverse mechanical response of unidirectional (UD) fibre-reinforced polymer (FRP) laminae. Using the DEM model, crack initiation and propagation in defective RVEs with different fibre distributions are analysed and compared. In addition, the effects of the distribution of the defects on stress–strain responses are also investigated. The DEM model shows excellent capabilities in predicting the crack path at failure that is consistent with experimental tests. Based on a data set generated by 1000 DEM simulations, back-propagation deep neural network (DNN) models are developed for a fast determination of crack initiation and instantaneous critical load of the RVEs. The results show that both the initial crack and the critical stress of the laminae can be accurately and efficiently predicted by the data-driven DNN models with consideration of randomly distributed defects.

Added mass and damping forces of a floating tidal turbine undergoing pendulum motion

Many commercial engineering software programmes used to design floating tidal turbines neglect the added mass and damping because most of the code considers floating wind turbine designs, which is acceptable since air is significantly less dense than seawater. However, added mass and damping forces are important parameters that need to be included in the design of a floating tidal turbine. The increase in instantaneous time-dependent loading and changes in the natural frequency of a floating tidal turbine make these hydrodynamic forces non-negligible, especially for large turbines. The present study describes the construction of matrices of added mass and damping that can be used as inputs to simpler engineering models. These matrices were constructed by conducting three-dimensional blade-resolved CFD simulations for a floating tidal turbine operating under a prescribed pitch motion (i.e., pendulum-like motion) under various motion amplitudes and frequencies. The added mass and damping were also empirically extracted from the fluctuating thrust force, the empirical model derivation of which is given in this paper. Higher motion amplitude and frequency increase the pressure on rotor blades, which increases the amplitude of loading variations. A floating tidal turbine's mean power and thrust deviate from that of a stationary turbine due to suboptimal rotor operating conditions caused by the change in tip speed ratio (which is due to the apparent velocity variation). Formulations can be constructed (as functions of motion amplitude and frequency) to calculate added mass and damping forces based on the data of hydrodynamic forces provided in this paper, which can be applied to a conventional turbine design model. The added mass and damping forces increase the overall mass and damping of the floating rotor, respectively, which affects the motion and loading of the device.

An improved AAPI controller for enhanced DC-link transient performance of six-phase active rectifier application

The permanent magnet synchronous generators (PMSGs), especially those with multi-phase structure, are increasingly adopted to power large-scale vehicular system with DC distribution (e.g. more electric aircraft and electric-propulsion ship). The controller design is critical in these vehicular application as they are required to maintain desired transient performance under large system disturbances. In this paper, an improved adding a power integrator (AAPI) controller is designed and adopted to regulate the six-phase active rectifier, thus enhancing the transient performance of the system. The regulation of the multi-phase active rectifier feeding large amount of dynamic instantaneous constant power load (CPL) is firstly formulated as a second-order system by utilizing a bi-linear coordinate transformation. Then, an improved AAPI finite-time controller is designed considering both asymptotic stability and the transient stability of the system. Last but not least, the effectiveness of the proposal is validated by simulation.

Effect of Partially Correlated Wind Loading on the Response of Two-Way Asymmetric Systems: The Impact of Torsional Sensitivity and Nonlinear Effects

Load eccentricities in structural systems are associated with an increase in the torsional response. Typically, these eccentricities are defined based on the distance between the center of mass and the center of stiffness at a predefined story. If the structural system is subjected to dynamic loading, such as wind loading, instantaneous load eccentricities due to the displacement of the center of mass may occur. An evaluation of this nonlinear effect for two-way asymmetric systems under wind loading is presented in this study. To model the structural systems and the instantaneous load eccentricities, coupled nonlinear differential equations are assembled and solved by using the state space model. The structural systems proposed are subjected to time histories of turbulent wind forces, which are simulated based on a newly developed methodology that includes the correlation of wind forces. The impact of the instantaneous load eccentricities and correlation of wind forces and torsional moment on the wind-induced response of the structural systems analyzed is discussed in detail.

Development of an Instantaneous Loading Impact Test System for Containment of a Nuclear Power Plant during Aircraft Impact on Steel Bar Joints.

As major projects such as nuclear power plants continuously increase, it is inevitable that loopholes will arise in safety precautions. Airplane anchoring structures, comprising steel joints and acting as a key component of such a major project, directly affect the safety of the project due to their resistance to the instant impact of an airplane. Existing impact testing machines have the limitations of being unable to balance impact velocity and impact force, as well as having inadequate control of impact velocity; they cannot meet the requirements of impact testing for steel mechanical connections in nuclear power plants. This paper discusses the hydraulic-based principle of the impact test system, adopts the hydraulic control mode, and uses the accumulator as the power source to develop an instant loading test system suitable for the entire series of steel joints and small-scale cable impact tests. The system is equipped with a 2000 kN static-pressure-supported high-speed servo linear actuator, a 2 × 22 kW oil pump motor group, a 2.2 kW high-pressure oil pump motor group, and a 9000 L/min nitrogen-charging accumulator group, which can test the impact of large-tonnage instant tensile loading. The maximum impact force of the system is 2000 kN, and the maximum impact rate is 1.5 m/s. Through the impact testing of mechanical connecting components using the developed impact test system, it was found that the strain rate of the specimen before failure was not less than 1 s-1, meeting the requirements of the technical specifications for nuclear power plants. By adjusting the working pressure of the accumulator group, the impact rate could be controlled effectively, thus providing a strong experimental platform for research in the field of engineering for preventing emergencies.