Loading Device Research Articles

Research on Active Disturbance Rejection Algorithm for Loading Control of 3-DOF Parallel Robot

A three-dimensional (3D) loading device based on a pneumatic 3-universal-prismatic-universal (UPU) parallel manipulator (three chains with UPU joint each) is designed to apply time-varying multi-dimensional loads to a target. First, according to the principle of vector superposition and Newton–Raphson method, the inverse and forward kinematics of the loading device are analyzed. Second, based on the screw theory, the static mapping between the dynamic platform and actuations is derived. Third, a second-order mathematical model is established for pneumatic 3-UPU parallel mechanism based on proportional flow valve and a metal seal pneumatic cylinder. A referential inaccurate model is provided for the control algorithm during modeling. Fourth, based on active disturbance rejection control (ADRC) technique, a 3D loading control algorithm is proposed and dynamic loading control is realized. Experimental results show that the ADRC algorithm has good robustness against disturbances, the steady-state control accuracy is less than 2 N, and the mean square error in dynamic tracking (sinusoidal tracking at 0.2 Hz) is less than 10.5 N.

Investigation on overbreak and underbreak of pre-stressed tunnels under the impact of decoupled charge blasting

Decoupled charge blasting has shown its superior performance in achieving smooth tunnel profiles in underground excavation. In this study, through establishing an underground tunnel blasting similarity modeling (UTBSM) test system that incorporates a static stress loading device (SSL), a highspeed digital image correlation device (DIC) and a 3D laser scanning device (3DLS), field blast tests with concrete models involving set-aside circular and rectangular openings are first conducted to examine the influence of filling medium on the depth and area of overbreak and underbreak. Subsequently, a 3D finite element model is developed using LS-DYNA and validated against one of the test results, and the influences of decoupled coefficient, decoupled charge mode, filling medium, and in-situ stress condition are comprehensively investigated. Finally, an energy analysis encompassing internal energy and kinetic energy is performed. The experimental and numerical results show that water-decoupled blasting results in the largest overbreak and smallest underbreak due to the highest internal energy and kinetic energy, and the expanded polystyrene foam (EPS) effectively reduces the blasting energy exerted on concrete so that causes the minimum overbreak depth and volume. Both the overbreak and damage in burden decrease with increasing decoupled coefficient. Radial decoupled charge mode produces a higher energy transfer efficiency than axial charge mode, whereas eccentric charge mode outperforms in controlling overbreak and improving the excavation efficiency. Additionally, the increase of in-situ stress leads to a reduction in overbreak depth and damage volume in the burden, indicating that in-situ stress plays a favorable role in overbreak control during contour blasting. However, the restraining effect of in-situ stress on rock fracture warrants sufficient attention as it may result in blasting failure.

Experimental and numerical investigation on meso-fracture behavior of Beishan granite subjected to grain size heterogeneity

Research on crack evolution mechanism and failure pattern of Beishan granite is vital for evaluation of the engineering stability of disposal repository. The mechanical properties, especially the strong heterogeneity, significantly affect the cracking behavior of granite. To investigate the fracture behavior of heterogeneous granite, mesoscopic three-point bending tests were conducted on Beishan granite using an in situ scanning electron microscope (SEM) with a loading device, and the entire cracking process was observed in real time. Additionally, the effect of grain size heterogeneity on strength and deformation behavior of granite was quantitatively investigated by introducing a statistically defined heterogeneity index into the grain-based model in two-dimensional Particle Flow Code (PFC-GBM), and the crack development was characterized through fractal theory. The results demonstrated that fracture mechanism of granite is mainly tensile and shear failure, and the fracture surface of tensile failure is rough and irregular, which is mainly caused by the tearing between various mineral crystals, whereas the fracture surface of shear failure is relatively smooth, which is mainly caused by the dislocation and slip between minerals. The crack edge can be regarded as the damage zone, and the development of the main crack is promoted by the continuous generation and combination of micro-damage at the crack tip. The crack propagation path from a mesoscale perspective is a process of continuous crack orientation, which depends on the competition mechanism between mineral properties and maximum tensile stress. Generally, the granite strength tends to increase with the increase of heterogeneity.

Mixed-mode fracture study of Mode-I + III and II + III loading conditions in AA7085 using a new fixture

This study experimentally examines the onset of fast fracture and crack deflection in AA 7085 for both mode-I + III and mode-II + III fracture modes. A new loading device has been developed by modifying the Richards loading device to induce out-of-plane mode in addition to mode-I and mode-II loading. The specimens assembled with the loading device were loaded using a uniaxial testing machine. Specimen level boundary conditions were derived to determine the fracture parameters at the onset of fracture using XFEM. The deflection angle of the crack and the fracture envelope were compared against standard criteria to predict failure.

Corrosion behavior and mechanical property of Mg-4Li-1Ca alloys under micro-compressive stress

Biomedical materials may suffer from stress-induced corrosion when performing as implant materials at load-bearing sites, bringing about variations in the microstructure, corrosion resistance, and mechanical properties. In this study, the corrosion behavior and mechanical properties of an extruded Mg-4Li-1Ca alloy were investigated under different micro-compressive stresses (0–6 MPa) using a novel homemade loading device. Under 0–3 MPa of micro-compressive stress, the strong basal texture of extruded Mg-4Li-1Ca alloys was weakened and the internal stress gradient stimulated grain boundary migration to induce grain growth. Meanwhile, increased stress resulted in the precipitation of second-phase particles and the accumulation of residual stress, accelerating the corrosion rate due to preferential corrosion. However, with increasing stress, the volume fraction of the second phase increased, becoming the dominant factor controlling the corrosion rate, and residual stress was released for samples under 4.5–6 MPa of micro-compressive stress. Hence, surface corrosion product films rapidly formed and served as effective physical barriers, weakening the microstructural effect on the corrosion behavior. The yield strength of Mg-4Li-1Ca alloy reached 95.48 MPa under 3 MPa of micro-compressive stress owing to the dual effects of precipitation strengthening and shear-band strengthening. The relationships between microstructure, corrosion behavior, and mechanical property provide a theoretical foundation for understanding the degradation characteristics of the Mg-4Li-1Ca alloy under physiological loading and practical application.

Time-Resolved Quantification of Patellofemoral Cartilage Deformation in Response to Loading and Unloading via Dynamic MRI With Prospective Motion Correction.

In vivo cartilage deformation has been studied by static magnetic resonance imaging (MRI) with in situ loading, but knowledge about strain dynamics after load onset and release is scarce. To measure the dynamics of patellofemoral cartilage deformation and recovery in response to in situ loading and unloading by using MRI with prospective motion correction. Prospective. Ten healthy male volunteers (age: [31.4 ± 3.2] years). T1-weighted RF-spoiled 2D gradient-echo sequence with a golden angle radial acquisition scheme, augmented with prospective motion correction, at 3 T. In situ knee loading was realized with a flexion angle of approximately 40° using an MR-compatible pneumatic loading device. The loading paradigm consisted of 2 minutes of unloaded baseline followed by a 5-minute loading bout with 50% body weight and an unloading period of 38 minutes. The cartilage strain was assessed as the mean distance between patellar and femoral bone-cartilage interfaces as a percentage of the initial (pre-load) distance. Wilcoxon signed-rank tests (significance level: P < 0.05), Pearson correlation coefficient (r). The cartilage compression and recovery behavior was characterized by a viscoelastic response. The elastic compression ([-12.5 ± 3.1]%) was significantly larger than the viscous compression ([-7.6 ± 1.5]%) and the elastic recovery ([10.5 ± 2.1]%) was significantly larger than the viscous recovery ([6.1 ± 1.8]%). There was a significant residual offset strain ([-3.6 ± 2.3]%) across the cohort. A significant negative correlation between elastic compression and elastic recovery was observed (r = -0.75). The in vivo cartilage compression and recovery time course in response to loading was successfully measured via dynamic MRI with prospective motion correction. The clinical relevance of the strain characteristics needs to be assessed in larger subject and patient cohorts. 2 TECHNICAL EFFICACY: Stage 1.

Effect of mechanical stresses on degradation behavior of high-purity magnesium in bone environments

High-purity (HP) magnesium (Mg) has emerged as a promising biomaterial for supporting functional bone tissue. Our previous study found that mechanical stresses and the surrounding fibrotic tissue (subcutaneous) both play crucial roles in the degradation of HP Mg. However, due to challenges in the degradation and regeneration process in vivo, it remains unclear how stress affects HP Mg degradation in bone environments, limiting its further application. In this study, novel loading devices were designed and the effects of tensile and compressive stresses on HP Mg degradation in vivo and in vitro bone environments were quantitatively analyzed. In addition, bone osteointegration around HP Mg was explored preliminarily. Tensile stress increases the degradation rate of HP Mg in vivo and in vitro. HP Mg degradation in vivo is more sensitive to stress factors than in vitro, but the sensitivity decreases with corrosion time. The volume loss rate of HP Mg is multilinear with the applied stress and degradation time. The volume of bone tissue surrounding HP Mg is larger in the no-stress group compared to the stressed groups, which is more pronounced with increasing implantation time. These results provide valuable insights for optimizing the design of HP Mg-based implants considering load conditions. This will help to achieve a balance between the degradation rate of the implant and the regeneration rate of the surrounding bone.

The design and analysis of a novel lapping loading device using a compliant mechanism

A lapping loading device that makes use of a compliant mechanism for a novel ring-type tapered roller lapping method is proposed in this paper. A three-part guide post structure is designed using the new type of tapered roller processing principle. For the purpose of designing and analyzing of the three-part guide post structure, a pseudo-rigid-body model for the mechanism of the three-part guide post is developed. Based on the pseudo-rigid-body model, the loading mechanisms and the mechanical behavior of the three-part guide post structure were discussed in this work simultaneously. The computation model of the lapping force in the machining of the tapered roller lapping was developed and validated through the finite element method and experiment results. This shows that the developed computation model possess high enough accuracy to effectively control the lapping loading force. This research established the viability of using the compliant mechanism in the field of the tapered roller processing technique.

Effect of CrMoN addition on the thermal stability and cyclic impact resistance of TiVN coatings

By adding V atoms to TiN, the tribological and mechanical properties of TiVN coatings are improved. Multilayered coatings, rather than monolayered ones, may further enhance the mechanical properties and thermal stabilities of TiVN. Therefore, an approach was employed in this study to synthesize gradient-and-multilayered CrMoN/TiVN coatings through vacuum arc ion plating. During the impact fatigue test that utilized a cyclic loading device, the correlation between cyclic impact resistance and coating structures of the deposited coatings were evaluated. Vacuum annealing and high temperature oxidation at temperatures exceeding 600 °C were used to assess the thermal stability of the coatings. Although the as-deposited TiVN coating achieved the highest hardness of 30.2 ± 2.5 GPa, the CrMoN/TiVN multilayer coating only experienced a slight decrease to 29.1 ± 2.2 GPa, which exceeded the solid solution quaternary CrMoTiVN mixture rule prediction. When compared to the high-hardness monolayered TiVN and the low-hardness CrMoN, the CrMoN/TiVN multilayer coatings demonstrated the best resistance to cyclic impact. The TiVN coating displayed the worst oxidation resistance, as shown by the emergence of elongated vanadium-rich Ti-V oxide slats on the surface after oxidation. The CrMoN coating exhibited higher oxidation resistance than TiVN, and small granular chromium oxides formed on the surface beyond 700 °C. The addition of CrMoN to TiVN to form CrMoN/TiVN resulted in improved oxidation resistance by inhibiting the oxidation of TiVN. A different oxidation behavior was found for the CrMoN/TiVN coatings. The design of gradient-and-multilayered CrMoN/TiVN coatings is proven to be advantageous for applications that aim to enhance the thermal stability and cyclic impact resistance of mechanical tools.

Study on the semi-circular bend method for characterizing the mixed mode I/II fracture toughness of sandstone: A micro-perspective

Manufacturing and precracking specimens for semi-circular bend (SCB) tests are simple processes and do not require complicated loading devices. They have been used to conduct mode I, mode II and mixed mode I/II fracture tests on brittle materials. However, characterizing mode I and mode II fractures from a microcosmic and quantitative perspective has never been thoroughly evaluated. In this paper, high-resolution digital image correlation (DIC) and moment tensor inversion are first used to quantitatively measure micron-level displacement and analyse microfailure types. The DIC results indicate that SCB specimens with a notch inclination angle exhibit both opening displacement and sliding displacement, resulting in a mixed mode I/II fracture. A quantitative analysis of three typical classification methods based on moment tensor inversion suggests that SCB specimens with mixed loads are mainly tensile mechanisms. Some tensile sources are not pure tensile cracks, and shear components also play an important role. It is also observed that the moment tensor components, nature of sources and Hudson k value are associated with the notch inclination angle, which sheds new light on the mechanism of mixed mode I/II fractures.

Degradation behavior of 2D auxetic structure with biodegradable polymer under mechanical stress

Coronary heart disease is serious harm to human health. Vascular scaffold implantation is the main treatment. Biodegradable polymers are widely used in vascular scaffolds for good biodegradability and biocompatibility. However, whether the mechanical properties and radial expansion ability can successfully implant the scaffold without acute elastic retraction remains to be further studied. Because of the unique deformation mechanism, shear resistance, and resilience, auxetic structures can effectively avoid the restenosis of degraded vascular scaffolds. Firstly, the plane isotropic and plane anisotropic auxetic structural scaffolds were designed. The control structures (traditional structures) scaffolds were taken as the contrast. PCL was used to prepare the vascular auxetic by 3D printing. The printing parameters of fused deposition 3D printing, such as printing temperature, printing speed, and printing pressure, were studied to determine the optimal printing parameters of PCL. A self-assembled cyclic tensile stress loading device was used to investigate the degradation behavior of different scaffolds under different sizes of cyclic tensile stress, such as surface morphology, pH changes, mass loss rate, and mechanical properties. The increase of stress, surface roughness, and mass loss rate of the scaffolds all showed an increasing trend. pH gradually decreased from the fifth week, and the decrease was proportional to the stress. A large level of stress loading intensifies the decline of elastic modulus and the ultimate strength of the scaffold. In conclusion, the increase of periodic tensile stress will accelerate the degradation of scaffolds, and the degradation behavior of scaffolds with different configurations is different. The degradation rate of dilatant scaffolds was higher than that of control scaffolds, and the degradation rate of anisotropic auxetic scaffolds was higher than that of isotropic auxetic scaffolds, which provides a theoretical reference for the application of auxetic structure in the degradation of vascular scaffolds.

Progress in Experimental Research on Mechanical Behavior of Composite Solid Propellants

Composite solid propellant is a particle reinforced composite material, and its microstructure strongly affects its macroscopic mechanical properties. This article reviews the current research status of macroscopic mechanical experiments and microscopic experiments. In terms of macroscopic mechanical performance testing, based on the description of the number of loading axes used to load the specimen, the development of related experimental research on uniaxial loading is relatively mature, while research on multi-axial loading is still lacking, and a unified standard has not yet been formed. In terms of microscopic experiments, although there are currently many observation methods, each has its own advantages and disadvantages; In experimental studies on the microstructure observation of solid propellants under loading conditions, most of them are based on uniaxial loading devices combined with optical microscopes, scanning electron microscopes, or micro CT devices to conduct research on the microstructure damage process of solid propellants under uniaxial loading. However, the research on the microstructure damage evolution process of solid propellants under multi-axial loading is currently in a research gap at home and abroad. Finally, this article summarizes and comments on the current research status, Proposed the shortcomings of current research and the key areas that need to be studied.

In Situ Characterization of 17-4PH Stainless Steel by Small-Angle Neutron Scattering.

17-4PH martensitic steel is usually used as valve stems in nuclear power plants and it suffers from thermal aging embrittlement due to long-time service in a high-temperature and high-pressure environment. Here, we characterized the evolution of microstructures at the nano-scale in 17-4PH steel by in situ small-angle neutron scattering (SANS) with a thermo-mechanically coupled loading device. The device could set different temperatures and tensile so that an in situ SANS experiment could dynamically characterize the process of nanoscale structural changes. The results showed that with increasing thermal aging time, the ε-Cu phase precipitates and grows as the temperature is 475 °C and 590 °C, and the ε-Cu phase is spherical at 475 °C but became elongated cylinders at 590 °C. Moreover, the loading stress could aid in the growth of the ε-Cu phase at 475 °C.

Fracture properties of basalt-fiber-reinforced bridge concrete under dynamic fatigue loading

Basalt fibers with different lengths and contents were incorporated into concrete to improve the expansion and extension of microfractures in bridge deck concrete. A fracture performance test of basalt-fiber-reinforced bridge concrete (BFRBC) was conducted using a three-point bending loading test. A fatigue test was performed using a self-designed loading device, and load stress levels of 0.5 and 0.7 were used to investigate the deterioration trend of the fracture toughness of the BFRBC under dynamic fatigue loading. The inhibition effect of basalt fiber on concrete cracks under fatigue loading was investigated. The crack resistance mechanism of basalt fiber on concrete under fatigue loading was revealed by scanning electron microscopy using Image-Pro Plus and MATLAB software to extract relevant crack parameters. The results of the fracture performance of BFRBC showed that basalt fiber with an appropriate length and content can greatly improve the fracture performance of concrete, and 12-mm basalt fiber was adopted in concrete with a content of 0.08%. At a stress level of 0.7 after 200,000 fatigue load cycles, the deterioration of concrete without fiber content was the most significant, and the initial fracture toughness and unstable fracture toughness decreased by 22.67% and 29.28%, respectively. In addition, the crack area density, average crack width, and maximum crack length of the BFRBC decreased by 46.69%, 21.94%, and 21.35%, respectively, because of the incorporation of basalt fiber. BFRBC disperses and transmits cracks through the bridging action of fibers in its internal stresses, delaying the generation and propagation of cracks and, thus, improving the crack resistance of concrete.

Simulation Methods for MEMS S&A Devices for 2D Fuze Overload Loading.

An experimental testing system for the two-dimensional (2D) fuze overload loading process was designed to address the loading issues of recoil overload and centrifugal overload in fuze safety and arming (S&A) device. By incorporating centrifuge rotation energy storage, impact acceleration simulation, and equivalent centrifugal rotation simulation, a block equipped with a fuze S&A device accelerated instantly upon having impact from a centrifuge-driven impact hammer, simulating recoil overload loading. The impact hammer was retracted instantaneously by adopting an electromagnetic brake, which resulted in the centrifugal rotation of the block around its track, to simulate the centrifugal overload loading. The dynamic equations of the experimental testing system and the equations of impact hammer motions were established, whereby the rotation speed of the centrifuge and the braking force of the electromagnetic brake were calculated and selected. A dynamic model of the collision between the impact hammer and block was established using ANSYS/LS-DYNA software for simulation analysis. The acceleration curves of the recoil overload and centrifugal overload with variations in the centrifuge speed, cushion material, and buffer thickness were obtained, which verified the feasibility of the proposed loading simulation method. Two-dimensional overload loading simulation tests were performed using the developed experimental testing system, and the acceleration curves of the recoil overload and centrifugal overload were measured. The test results indicated that the proposed system can accomplish 2D overload loading simulations for a recoil overload of several 10,000× g and centrifugal overload of several 1000× g.

Experimental Study of Influence of Freeze–Thaw Cycles on the Dynamic Properties of Weathered Sand-Amended Expansive Soils

Expanded soils are widely distributed in Xinjiang, China, so roadbeds will inevitably pass through the areas of the expansive soil during road construction. While Xinjiang belongs to the seasonal frozen region, subjected to a freeze–thaw cycle, mud pumping is likely to occur in the subgrade under dynamical load. To study the dynamic properties of expansive soil for a range of freezing–thawing cycles and weathered sand contents, a series of dynamic triaxial tests were performed using a medium-scale true triaxial apparatus equipped with the cyclic loading device. And the maximum dynamic elastic modulus (Edmax) and ultimate dynamic stress amplitude (σdmax) were quantitatively analyzed by the modified Hardin–Drnevich three-parameter model, on which the expression of the damage degree under the joint action of both was established. The results indicate that the dynamic performance of expansive soil is greatly affected by freezing–thawing. Under the same weathered sand content, the maximum dynamic elastic modulus and the maximum dynamic stress amplitude of soil are inversely related to the number of freezing–thawing cycles. And, those two parameters tend to be stable after the sixth freeze–thaw cycle. Under the same number of freeze–thaw cycles, the maximum dynamic elastic modulus and the maximum dynamic stress amplitude firstly decrease and then increase with the increase in the weathered sand content. The critical dosage of weathered sand is 10%, and the strength of the improved soil reached the minimum value under this context. The damage degree model that integrates the effects of freeze–thaw cycles and the weathered sand can better predict the damage degree of soil.

Analysis of mixed-mode Compact-Tension-Shear (CTS) specimens with slanted propagating cracks

Compact-Tension-Shear (CTS) specimen with its loading device has been widely used in mixed-mode I&II fatigue crack growth (FCG) experiments. To accurately describe the FCG behavior of materials, it is necessary to determine both the crack length and the parameters that represent crack driving force or crack front stress field in real-time. However, the relevant solutions are currently incomplete or insufficient. In this paper, for CTS specimen with slanted propagating crack, the variations of stress field parameters including stress intensity factors (SIFs) and T-stresses, as well as crack-mouth-opening-displacement (CMOD) compliance were investigated through finite element (FE) analysis. The results show that KI, KII and T11 are greatly influenced by the initial crack length ratio, the slanted propagating crack length ratio and the loading angle, but rarely by the specimen thickness among the considered range of geometries; T33 as an out-of-plane constraint parameter, however, is subject to the coupling effects of in-plane geometries, out-of-plane geometries and the mixed-mode loading. Moreover, it is shown that the measurement span has an effect on CMOD-compliance results for CTS specimens under mixed-mode loading, which is only negligible within the recommended range of D/W∈(0.02, 0.16]. Finally, the accuracy of the developed CMOD-compliance equations was validated through FCG experiments. The conclusions obtained in the current work will provide usable constraint-related crack front stress field parameter solutions for the analysis of FCG behavior in mixed fracture mode, and also give a reliable non-visual method for the determination of fatigue propagating crack length in CTS experiments.

Cassette Loading Units for Hanging Devices of Breeding Seeders

The cassette loading device of breeding seeders is designed for sequential movement of cassettes with seed material to the sowing apparatus of the seeder. (Research purpose) The research purpose is reviewing of breeding seeders with a cassette loading unit for sowing machines and analyzing the technical solutions used in the devices. (Materials and methods) Conducted a review of cassette seeders for sowing various crops in breeding and primary seed production in order to find effective technical solutions. We compared different design solutions of cassette loading devices and chose the most rational design elements. (Results and discussion) The direction of improvement towards the robotization of a cassette device for loading breeding seeders was revealed, which increases the productivity of this auxiliary operation and reduces the use of manual labor. A classification of cassette loading devices used on breeding seeders was proposed. Formulated the technical task of developing a new device design. (Conclusions) We analyzed domestic and foreign technical solutions of cassette loading devices for sowing machines of breeding seeders, determined their technical and technological features. It was established that the improvement of the cassette device for loading breeding seeders, which increases the productivity of this auxiliary operation and reduces the use of manual labor, should be implemented in the direction of robotization of the process of operation of the cassette loading device. It was stated that in order to create a robotic cassette loading device, it is necessary to develop a manipulator controlled by a programmable electronic controller and a control system that ensures: moving cassettes along a guide (carrier) plate and feeding them to the holes for unloading seed material into the loading cylinders of sowing machines; sequential feeding of cassette blocks to a cassette table (in the working area); synchronization of the seeding machines with the operation of the loading device.

Determination of the fracture toughness of a 9Cr ODS steel fuel cladding using the pin loading Tension test

A Pin Loading Tension (PLT) test was developed to evaluate the fracture behavior of thin-walled tubes. The fracture resistance curve (J-R curve) was determined from the load-CMOD curve using the single specimen technique based on the elastic unloading method following the procedure described in the ASTM E1820-22e1 standard [1]. However, the standard does not provide the necessary functions, geometric function f(a/W) and plastic factor ηpl, to apply the methodology to the PLT test. In this work, the geometric functions needed to evaluate the crack length from the unloading compliance, which allows to highlight effects not seen in the past and the elastic and plastic parts of the J-integral were determined using finite element analysis. Special care was taken to consider the effects of contact and friction between the test specimen and the loading device. The methodology was then applied to experimentally study the crack growth resistance of a 9Cr ODS (Oxide Dispersion Strengthened) steel tube, which is a candidate material for fuel claddings of future fast-neutron reactors.

Power stand with a combined loading device for testing motor-wheels and their control systems

The article describes the implemented design of a prototype single-drum power bench with a combined load device and an automated measurement system for testing motor-wheels and their control systems. Algorithms for testing motor-wheels with a diameter of 100 to 700 mm and a power of up to 5 kW are proposed, providing a clamping force to the running drum up to 1500 N. The results of testing a motor-wheel, a control system for small vehicles using friction and inertial loading devices are presented. Keywords: electric transport, power stand, motor-wheel, tests, electric drive control systems, traction characteristic, acceleration characteristic, ADC