Three-dimensional Loading Research Articles

Effects and mechanism of negative pressure microenvironment on the neogenesis of human umbilical vein endothelial cells

Effects and mechanism of negative pressure microenvironment on the neogenesis of human umbilical vein endothelial cells

A differential evolution algorithm with ternary search tree for solving the three-dimensional packing problem

The three-dimensional packing problem, which is a strongly NP-hard problem and extremely difficult to solve in practice, is a typical issue in container loading. The container loading problem (CLP) is a combinatorial optimization problem with complex constraints. Its solution process is complicated, and the amount of computation is large. Although some studies used exact algorithms, they could not obtain the optimal solution in a reasonable time. Therefore, heuristic algorithms and intelligent optimization algorithms have become the preferred choice for solving the three-dimensional container loading problem (3D-CLP). Differential evolution algorithm (DE) is an efficient intelligent optimization algorithm, which has remarkable effect in dealing with optimization problems. In this paper, we propose a novel technique that combines a differential evolution algorithm with a ternary search tree model (TSTDE) to solve the 3D-CLP. TSTDE utilizes the ternary tree model to generate a set of suboptimal solutions as the initial population of DE. The improved differential evolution algorithm is used to search the feasible solution of the problem. In this paper, we used the Bischoff and Ratcliff instances to test the TSTDE algorithm, and the results solving the 3D-CLP were compared with those of other advanced algorithms. The experimental results verified the feasibility and superiority of TSTDE in handling the 3D-CLP.

Pitch/Plunge Equivalence for Dynamic Stall of Unswept Finite Wings

Pitch/plunge equivalence for deep dynamic stall of a straight finite wing is considered by employing large-eddy simulations. The flowfields are computed with a well-established time-implicit high-fidelity large-eddy simulation approach. The wing has a moderate aspect ratio of and a NACA 0012 section incorporating a rounded tip. The flow parameters are a freestream Mach number of and chord Reynolds numbers of . Pure pitching and equivalent plunging maneuvers are considered with a reduced frequency of and minimum and maximum effective angles of attack of 4 and 22 deg, respectively. The pitch and plunge dynamic stall cases are compared in detail in terms of the unsteady three-dimensional flow structure, surface pressure, and loading. Differences in the lift and moment coefficient are shown to be correctable, employing a steady thin-airfoil theory for a cambered airfoil that accounts for the rotation-induced apparent camber present in the pitching case. This pitch/plunge equivalence is extendable to the dynamic stall of a swept wing, as demonstrated in another paper by the authors [“Pitch–Plunge Equivalence for Dynamic Stall of Swept Finite Wings,” AIAA Journal (submitted for publication)].

Effect of Stress Level on the Microstructural Evolution of Clay under Creep

Creep in clay can significantly affect long-term deformation evolution and therefore impact the safety of geotechnical structures. To improve our understanding of the mechanism of creep, we have examined the microstructural evolution of a kaolin clay sample submitted to creep under three-dimensional or axisymmetric loading conditions, focusing on the effect of the stress level. This experimental study identifies the local mechanisms in normally consolidated and overconsolidated remolded clay samples during creep under triaxial conditions at different stress levels. The results show that the macro and micro behaviors of the kaolin clay are predominantly governed by the contractancy or dilatancy mechanism activated along stress paths at constant p′. Within the contractancy domain, the scanning electron microscopy (SEM) observations showed that the microstructural anisotropy increased with the augmentation of the stress level. Microstructural evolution during creep can be attributed to changing patterns in particle reorientation and pore geometry, resulting in plastic strain hardening or softening as well as in viscous fluid flow. The evolution of the clay microstructure therefore depends on both the stress level and the over consolidation ratio (OCR). The differences in the orientation pattern under creep appeared to be enhanced according to the contractancy or dilatancy mechanism. The dilative specimens exhibited particle orientations that were relatively random. The flattening or expansion of micropores under creep corresponded to the contraction or dilation mechanism at the specimen scale. An attempt based on the analysis of the SEM photographs was made to evaluate the evolution of anisotropy during the different loading phases.

Ориентационная природа эффекта деформационной памяти при трехосном циклическом неравнокомпонентном сжатии песчаника

Для описания механизмов и условий проявления эффекта деформационной памяти (эффекта Кайзера) в горных породах, подвергающихся трехмерному непропорциональному циклическому нагружению с изменением ориентации и формы эллипсоида Ламе, проведены эксперименты с кубическими образцами из полимиктового песчаника на Испытательной системе трехосного независимого нагружения с непрерывной записью сигналов акустической эмиссии. Результаты непропорционального трехосного сжатия по разработанной 9-цикловой программе нагружения показали, что доминирующим механизмом проявления эффекта памяти повреждений в каждом определенно ориентированном ансамбле дефектов является развитие микротрещин нормального отрыва, ориентированных субнормально к направлению минимального главного напряжения. Было обнаружено, что проявление эффекта Кайзера определяется не столько фактом раскрытия существующих «благоприятно» ориентированных микротрещин, сколько их дискретным ростом и появлением новых дефектов. Полученные экспериментальные результаты могут рассматриваться в качестве триггера для развития моделей деформирования и разрушения горных пород, учитывающих анизотропную природу и ориентационные эффекты развития поврежденности при различных сложных напряженно-деформированных состояниях и реальных условиях трехосного непропорционального нагружения, которые наблюдаются в природных и антропогенных системах.

A hybrid matheuristic approach for the vehicle routing problem with three-dimensional loading constraints

This paper proposes a matheuristic algorithm based on a column generation structure for the capacitated vehicle routing problem with three-dimensional loading constraints (3L–CVRP). In the column generation approach, the master problem is responsible for managing the selection of best-set routes. In contrast, the slave problem is responsible for solving a shorter restricted route problem (CSP, Constrained Shortest Path) for generating columns (feasible routes). The CSP is not necessarily solved to optimality. In addition, a greedy randomized adaptive search procedure (GRASP) algorithm is used to verify the packing constraints. The master problem begins with a set of feasible routes obtained through a multi-start randomized constructive algorithm (MSRCA) heuristic for the multi-container loading problem (3D–BPP, three-dimensional bin packing problem). The MSRCA consists of finding valid routes considering the customers' best packing (packing first-route second). The efficiency of the proposed approach has been validated by a set of benchmark instances from the literature. The results show the efficiency of the proposed approach and conclude that the slave problem is too complex and computationally expensive to solve through a MIP.

A Three-Dimensional Mechanical Loading Model of Human Osteocytes in Their Native Matrix

Osteocytes are mechanosensory cells which are embedded in calcified collagenous matrix. The specific native matrix of osteocytes affects their regulatory activity, i.e., transmission of signaling molecules to osteoclasts and/or osteoblasts, in the mechanical adaptation of bone. Unfortunately, no existing in vitro model of cortical bone is currently available to study the mechanosensory function of human osteocytes in their native matrix. Therefore, we aimed to develop an in vitro three-dimensional mechanical loading model of human osteocytes in their native matrix. Human cortical bone explants containing osteocytes in their three-dimensional native matrix were cultured and mechanically loaded by three-point bending using a custom-made loading apparatus generating sinusoidal displacement. Osteocyte viability and sclerostin expression were measured 1–2 days before 5 min loading and 1 day after loading. Bone microdamage was visualized and quantified by micro-CT analysis and histology using BaSO4 staining. A linear relationship was found between loading magnitude (2302–13,811 µɛ) and force (1.6–4.9 N) exerted on the bone explants. At 24 h post-loading, osteocyte viability was not affected by 1600 µɛ loading. Sclerostin expression and bone microdamage were unaffected by loading up to 8000 µɛ. In conclusion, we developed an in vitro 3D mechanical loading model to study mechanoresponsiveness of viable osteocytes residing in their native matrix. This model is suitable to study the effect of changed bone matrix composition in metabolic bone disease on osteocyte mechanoresponsiveness.

Real-time replication of three-dimensional and time-varying physiological loading cycles for bone and implant testing: A novel protocol demonstrated for the proximal human femur while walking

In vitro real-time replication of three-dimensional, time-varying load profiles acting on human bones during physical activity can advance bone and implant testing protocols. This study aimed to develop a novel protocol for applying the three-dimensional, time-varying hip contact force while walking to a human femur specimen. The target force profile was obtained from the literature. A proximal femur from an elderly female donor was instrumented using ten rosette strain gages and tested using a custom-made hexapod robot. A load-control algorithm determined the robot position generating the target force at low frequency (0.0004 Hz). Five cycles of the robot position were played back at five intermediate frequencies up to real-time (0.04, 0.08, 0.16, 0.4, and 0.8 Hz). The hip reaction force, the length of the actuators (position), and cortical strains were compared. The error in the load-control force was 0.3 ± 4.2 N (mean ± SD). The last three force, position, and strain cycles varied by less than 1.1% for every frequency analyzed. Across frequencies, the force increased by 28% at 0.8 Hz as a logarithmic function of frequency (R2 = 0.98). The position and strain error linearly increased with frequency up to 0.4 Hz. The median position error and the interquartile range of the strain error reached 15% and 13% at 0.8 Hz. Changes of force and cortical strain at increasing frequencies were linearly related (R2 = 0.99). Therefore, the protocol developed can provide repeatable three-dimensional time-varying load profiles, although the comparison of the specimen deformation obtained across frequencies should be considered with care, particularly in the higher frequency range. This information supports the design of dynamic tests of bone and implants.

Three-dimensional loading control of a pneumatic three-universal–prismatic–universal robot

Multidimensional force loading has been widely used in the fields of component and material testing. The pneumatic-driven multidimensional force loading parallel mechanism can meet the requirements of complex force loading. A three-dimensional loading robot based on a pneumatic three-universal–prismatic–universal parallel mechanism is designed to apply time-varying three-dimensional loads on a target. Based on the principle of vector superposition, inverse and forward kinematics are deduced. A second-order mathematical model of a metal seal pneumatic cylinder driven by a flow proportional valve is established. Based on the immersion and invariance technique, the leakage flow in the cylinder is taken as the interference term and estimated. Meanwhile, because of the strong nonlinearity of the actuator, based on suitable disturbance estimation, the control rate of the system is designed through the sliding mode surface, and the stability of the control algorithm is analyzed on the basis of the Lyapunov stability theory. The experimental results show that the immersion and invariance controller exhibits a better control performance than the proportional–integral–differential controller: the steady-state control mean square error is reduced by approximately 21% on average and the dynamic (0.2 Hz) tracking mean square error is approximately 10.35 N.

Novel Large-Scale Three-Dimensional Fracturing Experimental Apparatus and Application to Vertical-Well Hydraulic Fracturing of Hard Roof

Abstract Effective control of high-position hard roofs (HHRs) is important to meet the requirements of safe and efficient mining. Vertical-well hydraulic fracturing (VWHF) is an innovative control method developed for releasing strong ground pressure behavior induced by HHRs. Understanding the hydraulic fracture extension law and its spatial form is critical for VWHF applications on HHRs. To address this problem, we have developed a large-scale three-dimensional fracturing simulation apparatus. The effective sample size is 2,060 by 1,200 by 1,200 mm. The primary loading subsystem maintains full closed-loop control of stress and displacement and can perform one-way, two-way, three-way, and step-wise independent loading and unloading with a maximum three-dimensional loading capacity of 10 MPa. The apparatus can achieve gas sealing of 3 MPa. The time-space distribution law of multiple parameters in the apparatus can be monitored using 240 simultaneous test channels, and experimental phenomena can be observed in real time using the visual monitoring system. The fracturing subsystem can achieve flow infinite transformation between 0 to 107 mL/min and water pressure up to 51.7 MPa. The apparatus simulates hydraulic (supercritical carbon dioxide or liquid nitrogen) fracturing of coal-rock mass under complex stress and a gas-containing environment. To the best of our knowledge, these are the first large-scale three-dimensional fracturing simulation experiments performed on hard roof sandstone samples. We analyze the distribution and change of acoustic emission signal and stress before and after fracturing and determine the hydraulic fracture propagation law, which reflects characteristics of hydraulic fracturing hard roof processes in a large-scale fracture network. These experiments validate the capability and reliability of the newly developed apparatus. The results provide strong technical support for VWHF to weaken HHRs.

The split heterogeneous vehicle routing problem with three-dimensional loading constraints on a large scale

This paper introduces a complex real-world problem on a large scale that combines the split delivery heterogeneous vehicle routing problem with three-dimensional loading and considers new routing and loading constraints. The problem aims to find a set of routes with minimum transportation cost by satisfying the demand of all customers and loading constraints. We propose a column generation-based heuristic algorithm that employs three heuristic algorithms to solve the subproblem and a hybrid algorithm for loading. Computational experiments on the literature instances indicate that the proposed algorithm can produce very near solutions to the literature algorithm's solutions in significantly shorter running times. This paper introduces real-world instances with 230 to 850 customers, several times larger than the existing benchmarks. The results of the proposed algorithm for real-world instances are effective, and compared to the current situation, it leads to a reduction of 20% in the average total cost of transportation. Also, the average number of vehicles is reduced by 36%.

Variation Law of Infrared Radiation Temperature of Unloading Fracture of Composite Coal-Rock

For composite mining coal-rock dynamic disaster, combining the theory of thermodynamics, damage mechanics, and other disciplines, the thermodynamic coupling mathematical model of composite coal-rock under an unloading condition is deduced, and the simulation model of composite coal-rock is established for numerical simulation. And the variation law of thermal infrared radiation under triaxial loading and unloading of composite coal-rock is analyzed and verified by experiments. The results show the following findings: (1) The distribution of thermal infrared radiation temperature of composite coal-rock is different in different stages of stress. The overall temperature of the temperature field is lower than the initial temperature field in the three-dimensional stress loading stage and the stage of stress-keeping pressure, but the internal temperature of the coal body is the highest. In the first stage of “loading and unloading,” the temperature of a coal seam increases slightly, and the temperature of other parts of the rock layer increases except for the circular low-temperature zone. In the second stage of “loading and unloading,” an alternating zone of high and low temperatures appears in the rock mass, and the temperature field is enhanced, among which the temperature field reaches the strongest after unloading the confining pressure. After jumping over the maximum stress, the temperature field decreases as a whole at the instability and rupture stage. (2) The variation of surface average thermal infrared radiation temperature ( T ave ) of composite coal-rock can be divided into the initial fluctuation stage, the linear heating stage, the local decline stage, the temperature sudden increase stage, and the fracture decline stage. At three different unloading rates of 0.003 MPa/s, 0.03 MPa/s, and 0.05 MPa/s, the T ave of coal body, floor rock, and roof rock reach the maximum before composite coal-rock instability and fracture, and the temperature change of the coal body is the most obvious. (3) Under different confining pressure unloading rates, the T ave of roof rock, coal body, and floor rock shows a strong linear relationship with stress after linear fitting. And the correlation between simulation and experimental results after fitting is above 0.89. The larger the confining pressure unloading rate is, the shorter the peak time of T ave arrives, and the larger the peak value. The comparison between the experimental results and the simulation analysis shows that the two results are consistent, and the research results can provide a theoretical basis for the prevention and control of dynamic disasters in coal and rock mining.

Development of a direct shear testing method using true triaxial apparatus

Instability of faults and weak joints of rock mass is affected by underground three-dimensional loading conditions as well as hydrostatical fluid pressure within pores and cracks. This paper presents a direct shear testing method to characterize the shear behavior of Kimachi sandstones under various pore pressures and joint roughnesses. The direct shear test was conducted under three mutually perpendicular loads and with various levels of pore pressure through effective utilization of a true triaxial loading system. An overview of the experimental method, its advantages, and results showing the usefulness of the experiment were presented. Sample permeability in the direction parallel to the joint was measured during the shear test.

Fracture angle prediction for matrix failure of carbon-fiber-reinforced polymer using energy method

In this study, an energy-based model for predicting the fracture angle of matrix failure in unidirectional carbon-fiber-reinforced polymer (CFRP) under three-dimensional mechanical loading was developed. The elastic stresses in the undamaged area and the frictional stresses in the damaged area were considered in determining the complementary free energy density in the CFRP damage process. The fracture angle of the transverse matrix failure was predicted based on the maximum dissipation rate of the energy density. The effect of the stress state in the damaged area on the energy density was analyzed under the matrix tension and compression failure modes. The predicted fracture angle was verified by comparison with existing strength-based matrix failure criteria under various stress conditions. The computational efficiency between the energy-based and strength-based failure criteria is compared and evaluated.

An efficient method for the three-dimensional container loading problem by forming box sizes

This study focuses on a real-world case that is defined as an extension of the container loading problem (CLP) with weakly heterogeneous types of boxes. A company producing plastic cups wants to increase its efficiency in container loading operations. To solve the problem, a hybrid approach including a static rule to rank orders and integer nonlinear programming (INLP) models is developed. INLP models form box sizes according to the properties of the cups, and determine the position of the boxes in layers while simultaneously minimizing the layer-depth. The presented approach is tested on real-world cases and benchmark data sets. The results show that simultaneously forming boxes and solving the CLP increases the effectiveness of container loading operations.

Modular assembly of enzyme loaded nanoparticles in 3D hollow fiber electrode for electrochemical sensing

We have developed a three-dimensional (3D) enzyme loading strategy by modular assembly of enzyme loaded nanoparticles with porous conductive membranes. A 3D conductive structure was fabricated as electrode via the poly-(3,4-ethylenedioxythiophene) (PEDOT) in-situ synthesized on hollow fiber membranes (HFMs) framework, retaining the original gradient porous structures and capillary effect. Using physical entrapment pattern, enzyme-carrying nanoparticles were modularly assembled in the 3D conductive support and their spatial distribution can be regulated by particle size-tuning. The obtained enzyme entrapped 3D composites can be applied as a promising electrode in electrochemical sensing and catalysis. HFMs provide large surface area and gradient porous structure for entrapping the enzyme-carrying nanoparticles in the confined micro-space. The physical entrapment improves the enzymatic stability and promotes full contact between the enzymes and the conductive/catalytic substrates. The conductive support creates an interconnected network to increase the electrode area and the response current, thus enhancing the sensitivity of biosensors. It shows fast current response (~3 s), wide linear range (glucose, 2–24 mM; lactic acid, 0.1–6 mM), high sensitivity, and low detection limit (glucose, 100 µM; lactic acid, 10 µM) towards cancer cell metabolism monitoring. This electrode structure can be further applied in multi-target array detection towards metabolic markers by modulating different enzymes on the conductive HFMs.

Failure envelops analysis for square mudmat foundations on undrained clays under three-dimensional loading

ABSTRACT As the permanent submarine support structures for subsea wells, pipeline manifolds and pipeline terminations, the mudmat foundation works under obviously complex, nonlinear and uncertain loading, which makes a great challenge for the research of the stability of mudmat foundation. In this paper, finite element method is utilised to investigate the behaviour of square mudmat foundation without embedment in NC clay to fully 3D loading conditions: V-H-M and V-H-T. According to the analysis results, the relevant failure envelop surfaces and formulas are proposed to predict the capacity of mudmat foundation. These results could be treated as reference for the design work of the mudmat foundation.

Experimental Study of Volumetric Fracturing Properties for Shale under Different Stress States

Shale gas can be commercially produced using the stimulated reservoir volume (SRV) with multistage fracturing or multiwell synchronous fracturing. These fracturing technologies can produce additional stress fields that significantly influence the crack initiation pressure and the formation of an effective fracture network. Therefore, this study primarily investigated the evolution of crack initiation and propagation in a hydraulic rock mass under various stress conditions. Combining the in situ stress characteristics of a shale reservoir and fracturing technology, three types of true triaxial volumetric fracturing simulation experiments were designed and performed on shale, including three-dimensional constant loading, one-dimensional pressurization disturbance, and one-dimensional depressurization disturbance. The results indicate that the critical failure strength of the shale rock increases as the three-dimensional constant loads are increased. The rupture surface is always parallel to the maximum principal stress plane in both the simulated vertical and horizontal wells. Under the same in situ stress conditions in the wellbore direction, if the lateral pressure becomes larger, the critical failure strength of shale rock would increase. Additionally, when the lateral in situ stress difference coefficient is smaller, the rock specimen has an evident trend to form more complex cracks. When the shale rock was subjected to lateral disturbance loads, the critical failure strength was approximately 10 MPa less than that in the state of constant loading, indicating that the specimen with disturbance loads is more likely to be fractured. Moreover, shale rock under the depressurization disturbance load is more easily fractured compared with the pressurization disturbance. These findings could provide a theoretical basis and technical support for multistage or multiwell synchronous fracturing in shale gas production.

Unloading contact mechanics analysis of elastic–plastic fractal surface

At present, there are many researches on the loading between contact surfaces, but it is also very important to predict the unloading process between rough surfaces. In this paper, based on the three-dimensional fractal loading model we built earlier and the unloading finite element results of the single asperity by Etsion et al., the unloading fractal prediction model between rough contact surfaces is established. The model takes into account the friction factor between surfaces, the three-dimensional fractal characteristics of rough surfaces and the elastic–plastic deformation mechanism of asperities. The model is compared with the unloading model based on the two-dimensional fractal curve established by Miao et al. and the finite element results. The results show that the unloading process between rough surfaces depends on the final loading state of the surface; the loading and unloading curves form a hysteresis loop, which represents the energy dissipation in a contact cycle; both the friction factor and fractal dimension of the contact surface have important effects on the unloading model.

A Cyclic Macro-Element Framework for Consolidation-Dependent Three-Dimensional Capacity of Plate Anchors

This paper presents a new macro-element modelling framework for plate anchors which enables the effect of pore water pressure changes and the related evolution of soil strength during the process of cyclic loading and consolidation to be captured. The proposed modelling framework combines an advanced macro-element model for plate anchors, expanded to capture the cyclic loading behaviour, with a simple one-dimensional model of undrained shearing and consolidation for a soil element representative of the whole soil mass around the anchor. The representative soil element tracks the effects of changes in effective stress on the soil strength, which in turn governs the anchor capacity in the macro-element model. The two modelling components are linked through a mobilised capacity compatibility condition. It will be firstly shown that such modelling framework is able to capture the expected changes in an anchor’s capacity related to cyclic pore pressure generation and consolidation under one-dimensional cyclic loading of the anchor. Then, the model will be used to explore the plate anchor’s behaviour and failure mechanisms under loading conditions which mobilise its full three-dimensional cyclic loading capacity. The macro-element model will identify some conflicting mechanisms (i.e., the anchor’s kinematic/rotation and soil weakening/strengthening) governing the three-dimensional capacity of the anchor.