Kinetics of Damage of Materials under Various Regimes of Re-Changeable Loads

Kinetics of accumulation of damages in engineering objects, which work at repeated-alternating soft and hard modes of loading of details and elements of constructions of vehicles (cars, cars, railway transport, etc.). When changing the direction of the load force to the opposite in the structural material there is a phenomenon of changing the kinetics of accumulation of damage, ie the damage factor at separation and shear changes, which affects the effective stresses and service life of equipment. This effect of the factor of the influence of repeated variables on the redistribution of the kinetics of damage accumulation is considered experimentally for materials with different plastic properties

Static Strength Analysis of Meat Grinder Frame

Meat is one of the agricultural commodities needed to meet protein needs, because meat contains high quality protein, which is able to contribute complete essential amino acids. The purpose of this paper is to design, analyze the static strength of the frame based on theoretical calculations and simulations on solidwork 2018 software. This machine consists of a frame, reservoir, grinding shaft, transmission, and electric motor. The results of the design obtained a Meat Grinding Machine with Length: 610 mm, Width: 500 mm and Height: 750 mm. The material used is 2024-O Alloy with a modulus of elasticity of 72,400 N/mm2. The load force obtained is 576.32 N. And the value from the analysis is the displacement value of 0.174 mm and for theoretical calculations, the displacement value is 0.176 mm. So, the value of the percentage error is 1.176%. For the von Mises value of 68,970 MPa, and for calculations based on the theory, the von Mises value is 52,499 MPa. So, the value of the error percentage is 0.238%. And for the value of the safety factor obtained a value of 1,087, and for calculations based on the theory, the value of the safety factor is 1.428. So, the value of the error percentage is 0.313%.

Microstructure and Properties of the Aluminum Alloyed with ZrO Powder Using Fiber Laser

The scope of the work covers the development of the relationship between the chemical composition of surface-modified aluminium and its mechanical properties. This article presents the impact of laser alloying with ZrO powder on the microstructure and mechanical properties of pure aluminium. In order to study the phenomena occurring during the laser alloying process, microstructural studies were carried out using optical microscopy. Additionally, the properties of the obtained alloy were tested - abrasion resistance and hardness measured at low load force. As a result of the alloying process, three distinct zones were identified: the remelting zone (RZ), the diffusion zone (DZ) and the heat affected zone (HAZ). The surface modification resulting from laser alloying increases the hardness and abrasion resistance of the material.

Nonlinear Cutterhead Pose Control of Large-Diameter Slurry Shields in Complicated Stratum

To replace cutterhead worn tools conveniently or get rid of shield’s jamming effectively in complicated stratum, a new nonlinear cutterhead pose control system of large-diameter slurry shields is especially designed. High precision cutterhead pose control of large-diameter slurry shields is hardly achieved due to the uncertain load force and mass. A nonlinear controller constructed by adaptive robust control based on sliding mode is designed for this parallel mechanism, which includes a special adaptation law to compensate for the uncertainties. The stability of the whole closed loop system is verified based on Lyapunov theory. And the validity of the proposed strategy is proved by Simulink and AMESim co-simulation. The simulation results show that not only in control accuracy but also in parameter uncertainty, the designed nonlinear cutterhead pose control is effective.

VERIFICATION OF FORCE TRANSDUCER FOR DIRECT AND INDIRECT MEASUREMENTS

Paper deals with verification of high load force sensor using the small weight weights. Test band was built for this purpose. Verification of test band were executed using the etalon reference sensor. Small forces were executed via using the direct method through the applying of weights. High forces were executed using the indirect method through the lever amplification of load derived from small weights. Uncertainties of measurement were evaluated.

Damage to engineering objects during re-static alternating load modes

The paper considers the kinetics of damage accumulation in engineering facilities that operate under repeated static alternating load modes - parts and structural elements of vehicles (cars, airplanes, railways). When changing the direction of the load force in the structural material there is a phenomenon of changing the shape of micro defects, which leads to their "healing", ie the factor of damage to separation and shear changes, which affects the effective stresses and service life of equipment. This effect of defect healing is considered experimentally for materials with different plastic properties.

Analysis and Verification of a Cogging Torque Reduction Method for Variable Flux Memory Permanent Magnet Machine

In this paper, an analytical method based on the series transform and skewed slot structure of rotor is adopted to reduce the cogging torque of the variable flux memory permanent magnet (VFMPM) machine. Firstly, the theory analysis of the cogging torque of the VFMPM machine was completed. Secondly, a simulation model of the VFMPM machine was established, aiming at calculating the cogging torque of the VFMPM machine and verifying the correctness of the above analytical method. Thirdly, a prototype of 14 rotor slots and 12 stator slots of the VFMPM machine was manufactured, and the experimental results of the cogging torque of the VFMPM machine further verified the effectiveness of the above mentioned theory analysis. Besides, the load force of the VFMPM machine including the cogging torque was also tested and analyzed in this paper.

Water-immersion finger-wrinkling improves grip efficiency in handling wet objects

For most people, immersing their hands in water leads to wrinkling of the skin of the fingertips. This phenomenon is very striking, yet we know little about why it occurs. It has been proposed that the wrinkles act to distribute water away from the contact surfaces of the fingertip, meaning that wet objects can be grasped more readily. This study examined the coordination between the grip force used to hold an object and the load force exerted on it, when participants used dry or wrinkly fingers, or fingers that were wet but not wrinkly. The results showed that wrinkly fingers reduce the grip force needed to grip a wet object, bringing that force in line with what is needed for handling a dry object. The results suggest that enhancing grip force efficiency in watery environments is a possible adaptive reason for the development of wrinkly fingers.

Neurophysiology of slip sensation and grip reaction: insights for hand prosthesis control of slippage.

Sensory feedback is pivotal for a proficient dexterity of the hand. By modulating the grip force in function of the quick and not completely predictable change of the load force, grabbed objects are prevented to slip from the hand. Slippage control is an enabling achievement to all manipulation abilities. However, in hand prosthetics, the performance of even the most innovative research solutions proposed so far to control slippage remain distant from the human physiology. Indeed, slippage control involves parallel and compensatory activation of multiple mechanoceptors, spinal and supraspinal reflexes and higher-order voluntary behavioral adjustments. In this work, we reviewed the literature on physiological correlates of slippage to propose a three-phases model for the slip sensation and reaction. Furthermore, we discuss the main strategies employed so far in the research studies that tried to restore slippage control in amputees. In the light of the proposed three-phase slippage model, and from the weaknesses of already implemented solutions, we proposed several physiology-inspired solutions for slippage control, to be implemented in the future hand prostheses. Understanding the physiological basis of slip detection and perception and implementing them in novel hand feedback system would make prosthesis manipulation more efficient and would boost its perceived naturalness, fostering the sense of agency for the hand movements.

Adaptation and compensation for somatosensory deficits in object handling: evidence from a patient with large fibre sensory neuropathy

The purpose of this study was to determine the contributions of feedforward and feedback processes on grip force regulation and object orientation during functional manipulation tasks. One patient with massive somatosensory loss resulting from large fibre sensory neuropathy, and ten control participants were recruited. Three experiments were conducted: 1) perturbation to static holding; 2) discrete vertical movement; and 3) functional grasp and place. The availability of visual feedback was also manipulated to assess the nature of compensatory mechanisms. Results from experiment 1 indicated that both the deafferented patient and controls used anticipatory grip force adjustments prior to self-induced perturbation to static holding. The patient exhibited increased grip response time, but the magnitude of grip force adjustments remained correlated with perturbation forces in the self-induced and external perturbation conditions. In experiment 2, the patient applied peak grip force substantially in advance of maximum load force. Unlike controls, the patient's ability to regulate object orientation was impaired without visual feedback. In experiment 3, the duration of unloading, transport and release phases were longer for the patient, with increased deviation of object orientation at phase transitions. These findings show that the deafferented patient uses distinct modes of anticipatory control according to task constraints, and that responses to perturbations are mediated by alternative afferent information. The loss of somatosensory feedback thus appears to impair control of object orientation, while variation in the temporal organization of functional tasks may reflect strategies to mitigate object instability associated with changes in movement dynamics.