Force Measurement System Research Articles

Structural design and optimization of a turning tool embedded with thin-film strain sensors for in-process cutting force measurement

A tool system integrated with machining and measurement is constructed by using thin film strain sensors and tool integration technology, which provides a new research method for studying the machining mechanism and automatic monitoring of the machining process. In this paper, three kinds—elastic sleeve type, fast insert type, and insert type—of tool cutting force measurement systems of the turning tool embedded with thin-film micro-sensors are designed. High strain sensitivity can be obtained through setting the elastic region of the tool bar on the premise of meeting the tool strength and stiffness. The system can realize integration between the thin-film strain sensor and tool bar quickly and efficiently. It is simplified as a cantilever beam structure for analysis after setting the shape of the sensor elastic substrate as a rectangle. The expression between strain and deflection of the elastic substrate is established when the free end is subjected to tangential force and bending moment, and the influence of the substrate’s structural parameters on the deflection is analyzed. In order to further improve the strain effect, six kinds of other shapes of the substrate structure are optimized, deducing the expression between the structure parameters and deflection; the corresponding substrate structure atlas is established, comparing and analyzing the deflection of the rectangular structure substrate. Five kinds of metal substrate materials are selected. In the functional film system of the thin-film strain sensor, the scheme of aluminum oxide and titanium nitride as the transition layer, silicon nitride as the insulating layer, and Ni–Cr alloy as the resistance grid layer is adopted. The research results show that this scheme can improve the adhesion between the insulating layer and the substrate, improve the resistance sensitivity coefficient of the sensor, and meet the application requirements of the cutting force measurement system.

靴底センサシステムを用いた歩行中の3次元床反力推定

There is a demand for the development of a ground reaction force measurement system that is not subject to location restrictions. In the current study, we developed a sole sensor system equipped with four high-capacity compact 3-axis force sensors using a Cr-N thin film. Using the sole sensor system, time-series data of the three-directional ground reaction forces during straight walking was estimated. Two models, a multiple regression analysis model and a Gaussian process regression model, were used for the estimation. The % root mean square error (%RMSE) and R2 values in the multiple regression analysis were 14.3 % and 0.419 in average in the left-and-right directions, respectively. The %RMSE and R2 values in the anteroposterior direction were 8.0 % and 0.869 in average, respectively, and those in the vertical direction were 8.2 % and 0.801 in average, respectively. The %RMSE and R2 values in the Gaussian process regression were 13.6 % and 0.458 in average in the left-and-right directions, respectively. The %RMSE and R2 values in the anteroposterior direction were 6.5 % and 0.891 in average, respectively, and those in the vertical direction were 4.8 % and 0.910 in average, respectively. In addition, in both models, the estimation accuracy in the 0-20% stance phase, which corresponds to the heel sensor contacting period, was lower than that in other stance phases.

A Novel Real-Time Clip Force Measurement Device Design for Cerebral Aneurysm Surgeries

Brain aneurysm is a balloon-like bulge of brain artery wall and may be ruptured easily causing cerebral hemorrhage with fatal consequences. For prevention of rupture of the aneurysm, clipping or coiling techniques are used. Clipping is the gold standard since coiling is not possible for some aneurysms. Neurosurgeons apply a suitable clip figure and aneurysm is ruptured under control. Since the permanent clips remain in the brain to close the artery wall after surgery, it is vital to press vein clipping with the correct force. This research aims to measure the clip closing force during the opening of the clip over the applicator. Hence, a clip force measurement system with single miniature load cell in one orthogonal direction was developed to enable measuring the closing force of the clip with higher accuracy at the time of opening the clip. Thanks to the miniature load cell, the mechanical design placed on the applicator made it possible to measure the force applied to the clip closing force. For placing this user friendly design onto the applicator, not obstructing the field of the neurosurgeon is also considered. The verification of the design has proven its ability of measuring the clip closing forces in real time by comparing the catalog values of the clips. Under the same experimental conditions, the closing forces for 10 clips in different figures were achieved with a maximum catalog value difference of 4.11%. Standard deviation of the results shows a very strong similarity between measurement and catalogue values.

A Novel Method for Field Measurement of Ankle Joint Stiffness in Hopping

Stiffness of ankle joint has been investigated in a wide range of biomechanical studies with a focus on the improvement of performance and reduction in the risk of injury. However, measuring ankle joint stiffness (AJS) using the existing conventional methodologies requires sophisticated equipment such as force plate and motion analyses systems. This study presents a novel method for measuring AJS during a hopping task with no force or motion measurement system. Also the validity of the proposed new method was investigated by comparing the results against those obtained using conventional method in which motion capture and force plate data are used. Twelve participants performed the controlled hopping task at 2.2 Hz, on a force platform, and six high speed cameras recorded the movement. To calculate the AJS in both methods, the lower extremity was modeled as a three linked rigid segments robot with three joints. In the new method, the contact time and flight time were used to calculate ground reaction force, and inverse kinematic and inverse dynamic approaches were used to calculate the ankle kinematic and kinetic. The AJS calculated using the new method was compared against the results of conventional method as the reference. The calculated AJS using this new method (506.47 ± 177.84 N·m/rad) showed a significant correlation (r = 0.752) with the AJS calculated using conventional method (642.39 ± 185.96 N·m/rad). The validation test showed a mean difference of −24.76% using Bland–Altman plot. The presented method can be used as a valid, and low-cost tool for assessing AJS in the field in low resource settings.

Lift Force Measurement in Landing Gears Dynamic Tests

Abstract As one of the key components of the aircraft in terms of both operation and safety landing gears are of special interest of the aviation regulations. During the touch down landing gears need to dissipate as much of the energy as possible maintaining the lowest volume and weight as required by the aviation design restrictions. According to the aviation regulations landing gears have to be tested in order to prove the dissipation of the calculated landing energy and to evaluate actual loads acting on the fuselage via the mounting nodes of the landing gears. The tests need to replicate the real landing conditions as closely as possible – including the lift force (or lift) acting on the aircraft during landing. The lift force during landing is not sufficient to maintain the aircraft in flight but acts as the relief force to the aircraft weight resulting in lowering loads applied to the fuselage and decreasing landing energy needed to be dissipated. The lift force or lift has to be taken into account during laboratory tests of landing gears. The lift force needs to be simulated in all of the landing gears dynamic tests: performance optimization, proof of the operation for the certification, and the fatigue evaluation. There are two main methods of applying the lift during the tests: equivalent/effective mass or direct lift application. The latter is used at the Landing Gear Laboratory of the Lukasiewicz Research Network – Institute of Aviation (where author works on daily basis). The lift is applied by the pneumatic cylinders built in the test stand. Until recently the control of the lift force value was performed indirectly by the measurement of the pressure inside the pneumatic system. Recently the experimental direct measurement system using force transducers was introduced in order to directly measure the lift force during every test. In the presented paper, the author gives an overview of the lift force measurement system including its design and the results of the preliminary use evaluation.

Abstract 12305: Cardiomyocyte Alignment Control Promotes the Electrical Integration and Improve the Contractile Function of Human Cardiac Tissue

Introduction: Alignment, as seen in the native myocardium, is crucial for maintaining the functional cardiac tissue. However, it remains unclear how cardiomyocyte alignment control influences cardiac function and the underlying mechanisms. The aims of our study were to fabricate aligned human cardiac tissue using a micro-processed fibrin gel and elucidated the effect of alignment control on contractile properties. Methods: We fabricated aligned human cardiac tissue through cultivating human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) on a micro-processed fibrin gel with inverted V-shaped ridges (MFG). The orientation index was calculated based on the Fourier analysis using Phalloidin staining images. The cardiac tissue function was evaluated with a contractile force measurement system. Results: The orientation index of hiPSC-CMs on MFG was significantly higher than that on the control fibrin gel (1.5±0.1 vs. 1.2±0.1, p<0.001, n=4) and that was close to the orientation index of an adult rat heart tissue (1.6±0.1), suggesting hiPSC-CMs on MFG were aligned more uniformly than the control. The contractile force, maximum contractile velocity, and relaxation velocity were significantly increased in aligned cardiac tissue compared with non-aligned cardiac tissue [contractile force (75bpm): 0.9±0.5 mN vs. 0.5±0.3 mN, p=0.02, n=11]. Motion capture analysis revealed cardiomyocytes in the aligned cardiac tissues showed more unidirectional contraction than the non-aligned cardiac tissues. Furthermore, the timing of contraction at five designated points in the tissues was significantly closed in the aligned tissue, suggesting cardiomyocyte alignment control might improve the systolic and relaxation function of cardiac tissue by promoting synchronous cardiomyocyte contraction. Conclusion: Cardiomyocyte alignment control promoted the electrical integration of cardiomyocytes and contributed to generate the strong contractile force. Understanding the molecular mechanisms of alignment control-mediated synchronous contraction of cardiomyocytes might provide us the new insights on electrophysiological properties of heart tissue.

Experimental study on wave-in-deck loading under focused wave conditions

This paper presents experimental results related to the wave-in-deck phenomena caused by focused waves. A series of experiments were conducted in a two-dimensional wave flume using varying deck clearances and focused waves with varying wave crest heights to measure the water velocity profiles, vertical forces, and pressure distributions under the deck. The velocity fields of the water under the deck were obtained using the particle image velocimetry (PIV) system, which was synchronized with the force and pressure measurement systems. The linear momentum and kinetic energy with and without the deck were calculated from the PIV velocity maps. The velocity profiles, linear momentum, and kinetic energy of the water under the deck were compared with those of the incident focused waves to investigate the effect of the deck on the water kinematics in relation to the force and pressure measurements recorded during the loading process. Meanwhile, the forces and pressure caused by the focused waves were compared with those caused by regular waves, and the results indicated that the upward vertical force and pressure caused by the focused waves were larger than those caused by the regular waves but that the downward force exhibited an opposite behavior. Based on the force measurements, the peak and impulse of the vertical force indicated negative linear relationships with the deck clearance, whereas the wave crest height was found to have a less significant effect on the vertical force than the deck clearance. The distribution of the peak pressure along the deck was analyzed in terms of the corresponding impulsiveness and pressure impulse to evaluate the severity of the local wave loads, and the results indicated that the region near the leading edge would likely experience a greater structural damage due to the wave-in-deck load compared with the region near the trailing edge.

Development and implementation of a dynamic force measurement system for automatic tool changer system and drawbar mechanism in machining center

Automatic tool changer system (ATCS) and drawbar mechanism (DM) are two of key basic parts for realizing the automatic tool-changing cycle in machining centers. The dynamic force in a tool-changing cycle plays an essential role in condition monitoring, fault diagnosis, and failure warning for the ATCS and DM. However, existing force detection systems have limitations in practical application. In this paper, a novel dynamic force measurement system (DFMS) is developed, which is based on a force sensing element installed on the BT40 tool holder and operating through a wireless network. The force sensing element is used to convert the dynamic force into the electrical signal. Digital measurements are collected from the 24-bit sigma-delta analog-to-digital converter with a programmable gain array, which then are transmitted to the upper computer software via a wireless transceiver. Besides, a Teager energy operator based dual-threshold two sentences endpoint detection method is proposed to recognize the temporal onset and offset of each force event in the dynamic force recording. Experimental results show that the DFMS is reliable and suitable to measure the dynamic force in automatic tool-changing cycles.

Development of a force measurement system with a large punctual measurement range

Atomic force microscopes (AFMs) are precise force measurement instruments that can be used to measure multiple surface properties, such as adhesion force, surface potential, and elasticity at the nanoscale. AFM is increasingly used in diverse fields, especially in industrial applications. However, most existing commercial AFMs provide a scanning range of less than a few 100 μm. Moreover, the size of the sample must usually be less than a few centimeters to fit the mechanical constraints of the device. In this paper, we propose a gantry-type force measurement system that can perform force curve measurements over a large range. The measurement range of the proposed device is 240 mm minus the sample width in air environments. In liquid environments, the measurement range is mainly limited by the size of the Petri dish. For instance, a measurement range of 41.5 mm can be achieved by using a Petri dish having a diameter of 85.5 mm. In the experiments, (a) surface adhesion measurements on the ultraviolet/ozone (UV/O3) treated glass slides in air and (b) surface potential measurements on a mica surface in water were performed. The experimental results were consistent with the values obtained by the commercial AFMs, which demonstrated the accuracy of the proposed system.

Design and fabrication of a full elastic sub-micron-Newton scale thrust measurement system for plasma micro thrusters

In this work, a force measurement system is proposed to measure the thrust of plasma micro-thruster with thrust magnitude ranging from sub-micro-Newtons to hundreds micro-Newtons. The thrust measurement system uses an elastic torsional pendulum structure with a capacitance sensor to measure the displacement, which can reflect the position change caused by the applied force perpendicular to the pendulum axis. In the open-loop mode, the steady-state thrust or the impulse of the plasma micro-thruster can be obtained from the swing of the pendulum, and in the closed-loop mode the steady-state thrust can be obtained from the feedback force that keeps the pendulum at a specific position. The thrust respond of the system was calibrated using an electrostatic weak force generation device. Experimental results show that the system can measure a thrust range from 0 to 200 μN in both open-loop mode and closed-loop mode with a thrust resolution of 0.1 μN, and the system can response to a pulse bit at the magnitude of 0.1 generated by a micro cathode arc thruster. The background noise of the closed-loop mode is lower than that of the open-loop mode, both less than 0.1 in the range of 10 mHz to 5 Hz.

APPLICATION OF RECURRENT NEURAL NETWORK IN RESEARCH OF INTELLIGENT WIND TUNNEL BALANCE

The shock tunnel ground test is vitally important to the research of the high-enthalpy aerodynamic characteristics of hypersonic vehicles, and the high-accuracy aerodynamic measurement is the key technology. When a force measurement test is conducted in an impulse shock tunnel, the flow field is established instantly after the starting process of shock tunnel, at this time, the great impact loads are acting on the force measurement system. The force measurement system is excited under the action of instantaneous impact, and the inertial vibration signal of the system cannot be rapidly attenuated during the short test time. The output signal of the balance will contain the interference due to the inertial vibration, which leads to a bottleneck in the further improvement of the accuracy of the transient force test. In order to improve the force measurement accuracy in the short-duration shock tunnel, the development of high-accuracy dynamic calibration technology is the key method to improve the performance of balance affected by inertial interference. Therefore, in this paper, recurrent neural network is used to train and intelligently process the balance dynamic calibration data, aiming to eliminate the vibration interference signals in the output dynamic signals. The error analysis of the current method is carried out, and the reliability of the current method is verified. The method is applied to the data processing of force test obtained in shock tunnel, and the effect of inertial vibration on the output signal of the balance is effectively reduced. According to the sample verification analysis of the intelligent model, the relative error of each component load is relatively small, where the case of high-frequency axial force component is about 1%. In the verification of wind tunnel force test data, the good results are also obtained, which are compared with those processed by the convolutional neural network model.

DEM simulation for draft force prediction of moldboard plow according to the tillage depth in cohesive soil

In the field of agricultural machinery, various empirical field tests are performed to measure the design load for optimal design of tractors and implement. However, field test performance is costly, time-consuming, and there are many constraints on weather and field soil conditions, requiring simulation utilization studies to overcome these shortcomings. Therefore, the objectives of this study are to perform agricultural soil modeling, draft force prediction simulation in function of tillage depth using discrete element method (DEM) software, and to verify the prediction accuracy by comparing with field test results. In this study, soil property measurement test was performed by soil depth considering target tillage depth (0–200 mm) using soil mechanical properties measurement system for DEM soil modeling. DEM soil model calibration was performed using virtual vane shear test and cone penetration test values instead of the repose angle test. In addition, field tests to verify the accuracy of draft force prediction simulation were performed using a measuring tractor equipped with a draft force measurement system, a tillage depth measurement system and an RTK-GPS (travel speed). As a result of the DEM simulation, it was found that the prediction accuracy of the draft force was within 7.5% (5.1–9.9%) when compared to the measured draft force through field test. In addition, it was confirmed that the result was 5.3–61.6% more accurate than those obtained through existing theoretical methods used to predict draft force. On the other hand, the error of draft force prediction using DEM simulation considering only topsoil properties showed 20.3% lower prediction accuracy than the DEM soil model considering the soil properties of different soil layer. This study provides useful information for the DEM soil modeling process that consider the change in soil properties according to the tillage depth from the perspective of agricultural machinery research and it is expected to be utilized in agricultural machinery design research.

Flexible High-Resolution Force and Dimpling Measurement System for Pia and Dura Penetration During In Vivo Microelectrode Insertion Into Rat Brain.

Objective:Understanding the in vivo force and tissue dimpling during micro-electrode implantation into the brain are important for neuro-electrophysiology to minimize damage while enabling accurate placement and stable chronic extracellular electrophysiological recordings. Prior studies were unable to measure the sub-mN forces exerted during in vivo insertion of small electrodes. Here, we have investigated the in vivo force and dimpling depth profiles during brain surface membrane rupture (including dura) in anesthetized rats.Methods:A µN-resolution cantilever beam-based measurement system was designed, built, and calibrated and adapted for in vivo use. A total of 244 in vivo insertion tests were conducted on 8 anesthetized rats with 121 through pia mater and 123 through dura and pia combined.Results:Both microwire tip sharpening and diameter reduction reduced membrane rupture force (insertion force) and eased brain surface penetration. But dimpling depth and rupture force are not always strongly correlated. Multi-shank silicon probes showed smaller dimpling and rupture force per shank than single shank devices.Conclusion:A force measurement system with flexible range and µN-level resolution (up to 0.032 µN) was achieved and proved feasible. For both pia-only and dura-pia penetrations in anesthetized rats, the rupture force and membrane dimpling depth at rupture are linearly related to the microwire diameter.Significance:We have developed a new system with both µN-level resolution and capacity to be used in vivo for measurement of force profiles of various neural interfaces into the brain. This allows quantification of brain tissue cutting and provides design guidelines for optimal neural interfaces.

Fatigue level detection using multivariate autoregressive exogenous nonlinear modeling based on driver body pressure distribution

Prolonged driving causes symptoms of fatigue in drivers and changes their physical condition during driving. The purpose of this paper is to use a force measurement system located in the driver’s seat by force-sensitive resistance pressure sensors in order to record the received information to predict fatigue by learning regression-based models. This system is designed with 16 FSR (Force Sensing Resistor) sensors mounted on the seat and its backrest that records the driver’s body’s data, based on the force exerted by the driver on the seat in standard mode and during driving at various times. Fatigue level prediction is based on the trained nonlinear autoregressive exogenous model. In this procedure, models based on multivariate regression are first trained, and then correctness is checked. In this paper, the fatigue index is divided into five parts from 0 to 100 included fully conscious, slightly tired, moderately tired, very tired, and extremely tired, so the criterion for diagnosis is crossing the 75% of fatigue index and entering the extremely tired range. The results show that nonlinear models based on exogenous autoregressive have better performance than the linear mode, and even in the nonlinear model of NARX neural network, the fatigue of one step ahead is well predictable. A flopped state will be predictable when the body is immersed in the seat due to fatigue, so is far from the standard sitting position and will be in the extremely tired warning range.

A reliability study of a novel visual ischemic palpation scale in an experimental setting

BackgroundManual palpation is an important part of the clinical examination and generally it has low reliability. The aim of this study was to assess the reliability of a novel method for discriminating 3 different levels of palpation force. MethodsThis reliability study included 96 healthy physiotherapists and physiotherapy students, who have been taught a new palpation graduated procedure called Visual Ischemic Palpatory Scale (VIPS), aimed to classify the applied pressure based on the finger's ischemia. Force was recorded by a force measurement system putting sensor over a rigid surface. To study the characteristic of VIPS the analysis of variance (ANOVA), Spearman rank correlation coefficient, Intraclass Correlation Coefficient (ICC), Standard Error of Measurements (SEM), and Minimal Detectable Change (MDC) were calculated. ResultsThree distinct degrees were found with distinct forces expression: 1st degree 76.04 g (95% CI 65.86–86.22), 2nd degree 307.87 g (95% CI 263.29–352.44) and 3rd degree 1319.48 g (CI 1204.73–1434.23). Male participants significantly recorded a greater force than females. Good to excellent reliability across degrees were found (0.89 [95% CI: 0.82–0.97]), and final agreement found that more than 65.6% of sample recorded a force in the cut-offs identified. SEM values became bigger as the recorded force increased and MDC were equal to 48.94 g, 188.73 g, and 379.24 g for 1st, 2nd, and 3rd degree, respectively. ConclusionsVIPS would appear to have three distinct degrees, sex dependent, with specific force expression for each degree and a good to excellent intra-rater reliability, but a poor agreement between raters.

Low-cost Position and Force Measurement System for Payload Transport Using UAVs

In recent years, multiple applications have emerged in the area of payload transport using unmanned aerial vehicles (UAVs). This has attracted considerable interest among the scientific community, especially the cases involving one or several rotary-wing UAVs. In this context, this work proposes a novel measurement system which can estimate the payload position and the force exerted by it on the UAV. This measurement system is low cost, easy to implement, and can be used either in indoor or outdoor environments (no sensorized laboratory is needed). The measurement system is validated statically and dynamically. In the first test, the estimations obtained by the system are compared with measurements produced by high-precision devices. In the second test, the system is used in real experiments to compare its performance with the ones obtained using known procedures. These experiments allowed to draw interesting conclusions on which future research can be based.

Assessment of human bioengineered cardiac tissue function in hypoxic and re-oxygenized environments to understand functional recovery in heart failure.

IntroductionMyocardial recovery is one of the targets for heart failure treatment. A non-negligible number of heart failure with reduced ejection fraction (EF) patients experience myocardial recovery through treatment. Although myocardial hypoxia has been reported to contribute to the progression of heart failure even in non-ischemic cardiomyopathy, the relationship between contractile recovery and re-oxygenation and its underlying mechanisms remain unclear. The present study investigated the effects of hypoxia/re-oxygenation on bioengineered cardiac cell sheets-tissue function and the underlying mechanisms.MethodsBioengineered cardiac cell sheets-tissue was fabricated with human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM) using temperature-responsive culture dishes. Cardiac tissue functions in the following conditions were evaluated with a contractile force measurement system: continuous normoxia (20% O2) for 12 days; hypoxia (1% O2) for 4 days followed by normoxia (20% O2) for 8 days; or continuous hypoxia (1% O2) for 8 days. Cell number, sarcomere structure, ATP levels, mRNA expressions and Ca2+ transients of hiPSC-CM in those conditions were also assessed.ResultsHypoxia (4 days) elicited progressive decreases in contractile force, maximum contraction velocity, maximum relaxation velocity, Ca2+ transient amplitude and ATP level, but sarcomere structure and cell number were not affected. Re-oxygenation (8 days) after hypoxia (4 days) was associated with progressive increases in contractile force, maximum contraction velocity and relaxation time to the similar extent levels of continuous normoxia group, while maximum relaxation velocity was still significantly low even after re-oxygenation. Ca2+ transient magnitude, cell number, sarcomere structure and ATP level after re-oxygenation were similar to those in the continuous normoxia group. Hypoxia/re-oxygenation up-regulated mRNA expression of PLN.ConclusionsHypoxia and re-oxygenation condition directly affected human bioengineered cardiac tissue function. Further understanding the molecular mechanisms of functional recovery of cardiac tissue after re-oxygenation might provide us the new insight on heart failure with recovered ejection fraction and preserved ejection fraction.

Adhesion forces for water/oil droplet and bubble on coking coal surfaces with different roughness

Surface roughness plays a significant role in floatability of coal. In the present paper, coking coal surface was polished by three different sandpapers and the surface properties were characterized by contact angle and roughness measurements. The effect of surface roughness on floatability was investigated by adhesion force measurement system for measuring interaction forces between droplets/bubbles and coking coal surfaces with different roughness. The results showed that the contact angle decreased with increasing roughness yet the adhesion force between the water droplet and coal surface increased owing to the increased contact line and the appearance of line pinning. Maximum adhesion forces between water and surfaces were 111.70, 125.48, and 136.42 μN when the roughness was 0.23, 0.98, and 2.79 μm, respectively. In contrast, under a liquid environment, the adhesion forces between air bubble/oil droplet and coal surfaces were decreased with increasing roughness because of the restriction by water. Maximum adhesion forces of increasing roughness were 97.14, 42.76, and 17.86 μN measured at interfaces between air bubble and coal surfaces and 169.48, 145.84, and 121.02 μN between oil droplet and surfaces, respectively. Decreasing roughness could be beneficial to the spreading of oil droplets and the adhesion of bubbles which is conducive to flotation separation.

The effect made by the interaction between rock and fibrous polymeric materials on the geotechnological processes

Introduction. When mining by opencast, mining enterprises use dams and dikes to create circulating water settling basins. The settling basins are equipped with layer drainages carrying groundwater off and ensuring stability of structures. Fibrous polymeric materials (geotextiles) can be used as drainages serving as protective and drainage layers in the bases of heaps in the process of metals leaching from rocks. Research methodology. Geotextile drainages are calculated taking into account the uniform pressure from the overlying rock mass. Local deformation of fibrous materials caused by the force action of coarse rocks is not taken into account. Experimental studies of rock pressure on fibrous polymer materials have been carried out. The force measurement system creates the required force, the depth of the cone penetration into the fibrous material is measured using a dial indicator. The materials with a bulk density of 70, 110, 130 kg/m3 were used. Results. Analysis and discussion. The above theoretical studies allow to consider the probable cases of macrocontacts between rock and fibrous media and determine the ratio of local deformation in order to clarify fibrous media sizes and characteristics in future function as drainage and protective materials. Conclusions. Local deformations of fibrous media at the contact points may amount to 30–40% locally reducing the drainage capacity of fibrous material. Therefore, when designing structures made of rock, such as dikes, dams, leaching heaps, it is required to increase the design height of fibrous drainage by 10–30% taking into account macrocontacts with rocks.

Experimental Evaluation of Multiple Frost Heaving Parameters for Preflawed Granite in Beizhan Iron Mining, Xinjiang, China

Ice-driven mechanical weathering in cold regions is considered a main factor impacting the stability of rock mass. In this work, the response surface method (RSM) was employed to evaluate and optimize the multiple frost heaving parameters to seek the maximum frost heaving force (FHF), in combination with experimental modeling based on a specially designed frost heaving force measurement system. Three kinds of rocks were prepared with parallel flaws in it having different flaw width, length, and cementation type, and these factors were used to fit an optimal response of the maximum FHF. The experimental results reveal five distinguished stages from the frost heaving force curve, and they are inoculation stage, explosive stage, decline to steady stage, recovery stage, and sudden drop stage. The sensitivity analysis reveals the influential order of the considered factors to peak FHF, which is the rock lithology, flaw width, flaw cement type, and flaw length. For low-porosity hard rock, increasing flaw width, flaw length, and flaw cement strength can improve the probability of frost heaving failure. It is suggested that rock lithology determines the water migration ability and influences the water-ice phase transformation a lot.