Average Axial Force Research Articles

Geometric parameters optimization of tap via response surface methodology and nondominated sorting dung beetle optimization algorithm

Taps are widely used in the thread machining system. However, excessive loads during the tapping process can increase tap wear, which can affect tap life. Therefore, effective methods need to be proposed to solve the problems of excessive load and severe wear during tap tapping. This articleproposes a geometric parameters (e.g. rake angle ( Ky), cone angle ( Kr), helix angle ( Kh), etc.) optimization method based on response surface methodology (RSM) and nondominated sorting dung beetle optimization algorithm for a tap, exemplified through the tapping process of 304 stainless steel. This method is based on axial force ( Fa) and torque ( T). Firstly, the finite element model for the tapping process of 304 stainless steel is established, and the orthogonal simulation is carried out. Secondly, predictive models of Fa and T are established according to the RSM. The interaction effects of geometric parameters on Fa and T are revealed. After that, the nondominated sorting dung beetle optimization algorithm is implemented for the optimization of Ky, Kr, and Kh. The TOPSIS evaluation model is introduced to evaluate the Pareto optimal solution. Finally, some verification experiments are finished. The optimized tap shows a reduction in average axial force by 44.69 N and a decrease in average torque by 2.67 N·m. Under the same conditions, the flank wear width is reduced by 15.71%. The optimization method of tap geometry parameters in this paper is proposed based on finite element simulation and intelligent optimization algorithm. This method can provide technical guidance for the optimization of tool geometric parameters.

Mechanical Behavior of Secondary Lining in Super Large-Span Tunnels Considering Temperature Effects

Temperature stress has a significant impact on the structural stress of (super) large-span tunnel lining, which can easily lead to structural fatigue damage and premature cracking. With the increasing scale and quantity of super large-span tunnels, the issue of temperature stress in secondary lining has attracted widespread attention. Previous studies have paid little attention to the influence of temperature stress on the structural internal forces of ordinary small–medium-span tunnels, but this influence cannot be ignored for super large-span tunnels. We take the Letuan Tunnel (a double-hole eight-lane tunnel) of the Binzhou-Laiwu expressway renovation and expansion project in Shandong Province as a case study and analyze the mechanical response of the secondary lining through on-site measurement. Moreover, a numerical simulation was conducted to evaluate the effects of self-weight and temperature stress on the secondary lining of the case tunnel. The results indicate that: the stress of the secondary lining concrete and steel bars is greatly affected by seasonal temperature changes. The compressive stress of the concrete and steel bars is significantly greater in summer than in winter, and the tensile stress is greater in winter than in summer. Furthermore, multiple measurement points have shown a phenomenon of transition between tensile and compressive stress states. The stress of concrete and steel bars fluctuates periodically with a sine function over time, with a fluctuation period of one year. The structural stress increases with the increase of summer temperature and decreases with the decrease of winter temperature. The fluctuation amplitude of stress in the inner side of the lining concrete and steel bars is greater than that on the outer side. Among them, the stress amplitudes of the inner and outer sides of the concrete are between 0.77–1.75 MPa and 0.44–1.07 MPa, respectively, and the stress amplitudes of the inner and outer steel bars are between 5–31 MPa and 7–13 MPa, respectively. The safety factors in summer are lower than those in winter. The minimum safety factors for secondary lining in summer and winter are 3.4 and 4.6, respectively, which can meet the safety requirements for service. The average axial forces of the secondary lining under the coupling effects of self-weight and temperature in winter and summer are 528 MPa and 563 MPa, respectively, which are significantly greater than the combined axial forces under their individual effects. The bending moment distribution of the secondary lining at the tunnel vault, inverted arch, wall spring and other positions under the coupling effect of self-weight and temperature is different from or even opposite to the bending moment superposition result under the two individual actions. The achieved results reveal that the influence of temperature stress on the service performance of the lining structure cannot be ignored, and the research results can provide useful reference for similar tunnels and related studies.

Predicting Axial Force in Friction Stir Welded Joints of AA7075-T6 and AA2024-T3 Using Machine Learning Techniques

The friction stir welding (FSW) process has gained popularity in joining various types of aluminum alloys. The heat generated during the process is caused by the friction between the shoulder of the welding tool and the workpiece. The axial force (Fz) of the weld plays a crucial role in the welding process. If the axial force is insufficient to generate heat will result in defective workpieces. Therefore, the aim of this study was to predict the axial force of the FSW process of dissimilar aluminum alloys (AA7075-T6 and AA2024-T3) using machine learning techniques. The data used to create the predictive model was obtained from experiments involving 5 factors, each with 2 levels: 1) welding speed (mm/min), 2) rotational speed (RPM), 3) type of tools, 4) plunge depth (mm), and 5) dwell time (sec). The axial force was measured using a dynamometer with a sampling frequency of 10 Hz. The predictive model was created using all 4 algorithms: AdaBoost, CatBoost, LightGBM, and XGBoost. The performance of the four predictive models was evaluated using four metrics: mean absolute error (MAE), mean absolute percent error (MAPE), mean square error (MSE), and root mean square error (RMSE). The results showed that the AdaBoost algorithm had the best performance, with MAE, MAPE, MSE, and RMSE values of 509.08, 0.24, 452591.73, and 672.75, respectively. The AdaBoost algorithm was then used to predict the axial force using a dataset of 29,282 data, with predicted minimum average axial force of 1871.6 N. When compared to the axial force measured in the experiment, which was 1265 N, the results showed that the AdaBoost algorithm was capable of predicting the axial force with acceptable accuracy.

Prediction of Axial Force on Dissimilar Aluminum Alloys Friction Stir Welding Using Design of Experiment

Friction stir welding (FSW) has become very popular for joining similar or dissimilar aluminum alloys. The heat used for this welding process is caused by friction between the welding tool and the workpiece which the axial force, the main parameter for heat generation, plays a very important role. Insufficient heat during welding will result in defective workpieces. This research is aimed to predict the axial force from the relevant factors of the FSW of dissimilar materials (aluminum alloys AA2024-T3 and AA6061-T6). The 23 full factorial design with center point was used for this experiment that consisted of 3 main factors: 1) rotation speed (rpm), 2) welding speed (mm/min), and 3) pin geometry each factor has 2 levels and 2 replications with the total of 20 experiments. The axial force data of each experiment were collected using a stationary dynamometer which obtained the data acquisition every 0.1 seconds (frequency of 10 Hz). The results from the design of experiment were analyzed by statistical method at the significance level of α = 0.05 which found that the significance and the optimum value of the main factors were rotation speed of 1500 rpm, welding speed of 35 mm/min, pin geometry of tri flat threaded, and the 2-way interaction between rotation speed and pin geometry. Furthermore, the prediction of the average axial force value on dissimilar aluminum alloys obtained from the specified parameters equals 478.91 N.

Crossover of energy deposition and semi-stable chemical bonding in the nonadiabatic dynamics of GaN under proton irradiation

Understanding the ion-solid interactions of charged particles in materials facilitates the development of ion beam irradiation techniques. Combining Ehrenfest dynamics and time-dependent density-functional theory, we investigated the electronic stopping power (ESP) of an energetic proton in GaN crystal and studied the ultrafast dynamic interaction between the proton and target atoms during the nonadiabatic process. We found a crossover phenomenon of ESP at 0.36 a.u. along the <100> and <110> channels, which is interpreted by the charge transfer between the host material and the projectile and the stopping force exerted on the proton. At velocities of 0.2 and 1.7 a.u., we demonstrated that the reversal of the average number of charge transfer and the average axial force resulted in the reversed energy deposition rate and ESP in the corresponding channel. Further analysis of the evolution of non-adiabatic electronic states revealed the existence of the transient and semi-stable N–H chemical bonding during irradiation process, which is introduced by the electron clouds overlap of N sp 3 hybridization and the s orbitals of the proton. These results provide meaningful information for the interactions between energetic ions and matter.

Prediction of various defects and material flow behavior during dissimilar FSW of DH36 shipbuilding steel and marine grade AA5083 using FE-based CEL approach

Dissimilar friction stir welding (FSW) of steel-Al is a very tedious job. Inappropriate welding process parameters can lead to the initiation of inevitable defects associated with dissimilar FSW processes. These can be presented as tunnel defects, void generation, excessive flash formation, and other surface irregularities. Using conventional experimental trials makes it usually challenging to identify such defects. This research adopted an Abaqus/Explicit® framework utilizing a 3D thermo-mechanical based coupled Eulerian-Lagrangian (CEL) methodology. In order to predict commonly observed defects in the FSW process, the proposed FEM uses the volume of fluid approach. By monitoring the material flow into and out of the computational/void domain, the suggested framework has made it feasible to predict surface, sub-surface, and volumetric defects. Defect formation is studied at a constant tool rotation speed of 875 rpm, welding speed of 90 mm min−1, and tilt angle of 0°. Tilt angles of 0° caused welding joints with a small tunnel defect. Thermal history, axial force variation, and material flow behavior are all strongly aligned with the principle of defect generation. An experimental trial has been conducted to validate the proposed finite element model. The previous analysis found that the average axial force closely matches the welding-related experimental findings with a percentage error of 7.85%. While a proportion error of approximately ∼0.57% was found between the compared numerical and experimental diameters of the pin end-hole defect. Furthermore, the proposed model accurately predicted the process of material flow along the thickness direction of the workpiece. It was seen that the stress generated at the root of the flashes reached a higher value ranging between 485.6 and 582.7 MPa. Finally, a good agreement between the numerical results and the experimental trial was established, showing the robustness of the developed computational FEM technique.

Design and Field Monitoring of a Pile–Anchor–Brace Supporting System in a Soft Soil Area

With the continuous development of urbanization and the rapid development of science and technology, the requirements for foundation pit engineering are getting higher and higher. Foundation pit engineering is gradually developing in the direction of larger area and deeper excavation. In engineering examples, the combined supporting structure of a pile–brace and pile–anchor for foundation pits is widely used, while the engineering examples supported by a pile–anchor–brace supporting system are less frequently used. Based on a super-large deep foundation pit project in Yancheng City, Jiangsu Province, China, according to the surrounding environmental conditions, the foundation pit support scheme, and on-site construction situation, the design and on-site monitoring of the pile–anchor–brace supporting system were introduced and analyzed. The results show that: (1) the deformation of the pile–anchor–brace supporting system shows an obvious spatial effect, and the horizontal displacement of the pile and soil of the long side direction is greater than the short side direction; (2) in the initial state, the deep horizontal displacement of the soil is in the form of a ‘cantilever’, but in the later stage it changed to the form of a ‘drum belly’, and both the brace and anchor cable can limit the displacement of the soil effectively; (3) the axial force of the brace develops rapidly in the initial stage, but its development tends to be gentle after the completion of the first anchor cable construction. Through on-site monitoring, it was found that the axial force of the ring brace was larger than that of the corner brace, which was larger than the opposite brace; and (4) the development trend of the axial force for the two rows of anchor cables is quite different. The average axial force of the first row of anchor cables is greater than the second row of anchor cables, and the development trend of the first row of anchor cables is steep first and then gentle, while the change trend of the second row of anchor cables is just the opposite.

Monitoring Axial Force Development in a Super-Long Pile during Construction Using BOFDA and Data Interpretation Approaches: A Case Study

Long-term monitoring data for super-long piles are scarce and valuable. This paper reports axial strain measurements of a cast-in-place large-diameter pile embedded 76.7 m into a “weathered trench” of granite in Nanshan District, Shenzhen, China, using BOFDA monitoring technology. An approach based on the load-transfer method to interpret data is proposed, in which the axial load at the pile head and the shear behavior at the pile–soil interface can be analyzed. Results show that these data can well reflect the increase in axial strain as the number of floors built increases, although there is deviation related to fiber cable bending due to the installation and compaction of concrete, and the complex loading condition at the pile head. Sensitivity analysis of parameters disclosed that the friction angle between the soil and the pile was approximately 10° for the cast-in-place pile monitored in this study, which is approximately one third of the interface friction angle, considering the slurry cake effect. The average axial force exerted on the pile head induced by building one floor ranged from 116.00 kN to 297.43 kN; this increased with the number of floors built and the total loads of the superstructure. This implies that the raft carried a large portion of the structural load during the early construction stage; piles gradually carried a major portion of the increased load due to continuous construction. The overall mobilized percentage of skin friction was approximately 40.8% when 40 floors were built, and the pile had the potential to carry more axial load.

Optimization and analysis of mine drainage pump with high efficiency and large flow

This paper aimed to systematically maximize hydraulic efficiency and pump head for mine drainage pump using numerical simulation method and optimization design method. First, the preliminary design of the pump is carried out according to the traditional design method, and then the impeller and diffuser of mine drainage pump are optimized by orthogonal test method and computational fluid dynamics numerical simulation method aiming at the hydraulic efficiency of the pump. The results show that under the rated working conditions, the hydraulic efficiency of the optimized mine drainage pump is 82.11%, the pump head is 25.94 m, and the hydraulic efficiency and pump head are increased by 3.58% and 1.53 m, respectively. Furthermore, under the flow conditions of 0.8 Qd, 1.0 Qd and 1.2 Qd, the average radial force of the optimized impeller is reduced by 22.4 N, 18.5 N and 13.1 N respectively, and the average axial force is reduced by 36.7 N, 30.2 N and 27.3 N compared with the original scheme. It indicated that the optimization effect of mine drainage pump is obvious. Through the analysis of the characteristics of the internal flow field, it is illustrated that the reasonable control of the internal flow law of the pump can effectively improve the hydraulic performance of the pump and improve the stability of the pump operation.

Measurement of Peristaltic Forces Exerted by Living Intestine on Robotic Capsule

Using robotic capsules for assessing gut health has been an emerging field since the early 2000s with researchers attempting to perform diagnosis, monitoring, and therapeutic functions inside the gut. The knowledge of peristaltic forces inside the intestine are crucial for designing the actuation mechanism of robotic capsules, however, the impact of peristalsis on a capsule has not yet been quantified. In this work, an analytical model is presented to study the peristaltic movement of the small intestine. For the first time, finite element simulations were conducted in COMSOL multiphysics to generate intestinal peristaltic forces, and analyze their impact on a robotic capsule. A capsule prototype (30 × φ12 mm) was developed to measure the peristaltic forces from living intestinal tissue, while an embedded system was used simultaneously to record the live data from the capsule-intestine interaction. In in vitro experiments, the intestine applied an average axial force of 226 mN and contraction cycles of 9 times/min, while the capsule prototype experienced maximum radial force of 180 mN. A specialized in vitro setup is developed to keep fresh ex vivo intestine samples alive for up to 6 h, while the capsule prototype measured the intestinal forces from the living tissue. This in vitro experimental setup provided an excellent model for the in vivo environment in terms of generating peristaltic movements, hence this force analysis will help in developing efficient prototypes for locomotion, anchoring, localization, biopsy, drug delivery, and sampling mechanisms for robotic capsules.

Experimental investigation of flow forming forces in Al7075 and Al2014 – A comparative study

Flow forming is an important cold forming process that is used for producing axisymmetric jobs. The present investigation discusses the flow forming of Al2014 and Al7075. The flow forming forces were measured in the axial, circumferential, and radial directions using a Lathe dynamometer. The impact of changes in feed and mandrel speed on flow forming forces has been analyzed. The investigation showed that the axial force is the main dominating force, followed by the radial force in both Al2014 and Al7075. The average axial force in Al7075 under the same set of conditions was around 13–20% higher than Al2014 depending on feed and mandrel speed. The present investigation also suggests the change in feed rate has higher effect in Al2014 as compared to 7075 keeping other factors as constant.

Design and Finite Element Analysis of Axial Low-frequency Vibration Tool-holder

Vibration-assisted drilling can significantly reduce the drilling force and cutting heat during deep hole machining, improve tools life and hole machining quality. As a branch of vibration drilling technology, axial low-frequency vibration-assisted drilling has a broad application prospect in the field of drilling because of its simple structure and easy implementation. A mechanical axial low-frequency vibrating tool-holder (ALVT) is designed, and the overall structure layout and working principle of the vibrating tool-holder are analyzed. The rotary motion of the machine tool spindle is used as the power input to drive the sinusoidal surface to rotate to achieve the amplitude output. The vibrating tool-holder model is simplified, and the ABAQUS finite element software is used to simulate the titanium alloy material for ordinary drilling and axial low-frequency vibration drilling (ALVD), and the axial force and cutting temperature changes are compared and analyzed. The results show that ALVD of titanium alloy can reduce the average axial force by about 47% and the cutting temperature by about 11%, which can significantly improve the drilling conditions and the quality of hole machining.

RC Beam–Column Connections Retrofitted by Steel Prop: Experimental and Analytical Studies

This paper studies the efficiency of a proposed retrofit technique to boost the seismic behavior of beam–column connections in existing deficient reinforced concrete (RC) moment frame systems with the consideration of constraint conditions such as the height of beams, using analytical, experimental, and numerical methods. The proposed retrofit method, called the “single steel prop and curbs”, consists of a diagonal steel prop element and two steel curbs that to the beam and column are laterally mounted. The internal force diagrams of the retrofitted exterior beam–column connections by analytical formulations are investigated and design strategies for promoting the efficiency of the single steel prop to achieve the expected efficiency proposed. To assay the validity and reliability of the proposed analytical procedure, experimental and numerical assessments were also conducted independently. Therefore, four deficient RC beam–column connections by single steel prop were retrofitted using three different cross-sectional areas and revival sheets and then accompanied by a control specimen subjected to cyclic loading. Next, numerical models were calibrated in ABAQUS software. Finally, by derivation of the props’ average axial force from experimental and numerical results, the beam shear coefficient, β, is calculated based on the analytical relations. These results confirmed good conformity between the experimental and numerical outputs as well as reliability of the analytical formulations. Also, the output results indicated that the retrofitted specimens had 53–78% bearing capacity and 146–217% dissipated energy more than the control specimen.

Study on Low Axial Load Friction Stir Lap Joining of 6061-T6 and Zinc-Coated Steel

Friction stir lap joining of 6061-T6 and zinc-coated steel was performed using a high rotation speed and small tools with different pin lengths. During the welding process, the average axial force ranged from 0.2 to 1.1 kN, which is smaller than that for conventional friction stir welding. Satisfactory surface formation was achieved using a pinless tool and smaller plunge depth. The highest failure load of 2.26 kN was achieved for a pin length of 0.3 mm, plunge depth of 0.3 mm, and welding speed of 50 mm/min. The specimen fractured at the advance side of the 6061-T6 base metal. A continuous and compact interface layer with a thickness of 5.2 μm was formed. The main component of the intermetallic compound at the interface was Fe4Al13. The intermetallic compound was tightly connected and bound to the steel galvanized sheet and aluminum side.

A combined supporting system based on foamed concrete and U-shaped steel for underground coal mine roadways undergoing large deformations

In order to develop a satisfied support scheme for roadways excavated in soft rock and subjected to large deformation in coal mines, a combined supporting system is proposed, which includes steel mesh, bolt, anchoring cable, shotcrete, compressible U-shaped steel, foamed concrete damping layer, and fractured rock cushion layer. The interpretation of the behavior of the supporting system is carried out by numerical analysis and field monitoring. The results from the numerical analysis reveal that: due to the fact that the foamed concrete absorbed most of the deformations of the surrounding rock, the shrinkage of the U-shaped steel was significantly reduced, and the relationship between the average axial force of the U-shaped steel and the foamed concrete thickness is a second order equation. It is further noticed that, in engineering practice, the damping effect was no longer evident when the thickness of foamed concrete exceeded 30cm. The field monitoring results show that both the force sustained by the U-shaped steel and the displacement of the surrounding rock exhibited a trend of increase in the first 20days after the support system was formed but the increasing trend reduced after that, which means the proposed combined supporting system is effective to control the large deformation of roadways excavated in soft rock.

Força requerida para o desprendimento de frutos de tomate industrial em diferentes estádios de maturação

A colheita do tomate destinado ao processamento, atualmente, é feita com colhedoras automotrizes; para isso, são necessários estudos que viabilizem a melhoria destas colhedoras, reduzindo assim perdas no campo. Este trabalho teve como objetivo quantificar a força necessária para o desprendimento do fruto de tomate de seu pedúnculo em diferentes estágios de maturação. O experimento foi realizado na Fazenda Madeira, no Município de Gameleira de Goiás-GO, e no Laboratório de Engenharia Agrícola da Universidade Estadual de Goiás. Nas condições de campo, os frutos foram retirados avaliando-se a força de tração no sentido axial do pedúnculo ao fruto e, em laboratório, nos sentidos axial e transversal. O trabalho foi realizado no delineamento experimental inteiramente casualizado, com fator único, com dez repetições. Os tratamentos foram os estádios de maturação, considerando tomates verdes, tomates pintados e tomates maduros. Os resultados foram submetidos à análise de variância, aplicando-se o teste de F e, quando significativo, o teste de Tukey, a 5% de probabilidade. A força axial média requerida para os desprendimentos foi de 14,69 N, com maior valor para os frutos maduros. Para o esforço transversal, os valores médios foram 0,98; 1,37 e 1,86 N para os frutos verdes, pintados e maduros, respectivamente.

Stability Analysis of Highway Tunnel through Mined-Out Area during Excavation Process

Tianpingzhai Tunnel on Dazhou-Wanzhou Expressway passes through the mined-out area, the spatial position of the goaf changes constantly comparing to the tunnel during excavation, and broken rock mass of the caving zone is most likely to collapse, which affects construction safety in return. Two dimensional computation models were built by using finite differential software FLAC to simulate excavation process when the coal-mined area is right above or below the tunnel. In 2D models, goaf strata were regarded as horizontal, and buried depth and coal thickness were limited to 300 meters and 0.5 meter respectively. The displacement around the tunnel, forces of primary lining, axial force of bolts and plastic zone of surrounding rock have been analyzed under these circumstances that the distances between tunnel and goaf are 1m, 6m and 12m. According to the results, when the distance between goaf and tunnel is less than 12 meters,underlying goaf has greater impact on the displacement around the tunnel and average axial force of bolts than overlying goaf, as well as the size of plastic zone of surrounding rock. Its strongly suggested to avoid underlying goaf if the tunnel have to pass through the mined-out area.

Effect of annular secondary conductor in a linear electromagnetic stirrer

This paper presents the variation of average axial force density in the annular secondary conductor of a linear electromagnetic stirrer. Different geometries of secondaries are considered for numerical and experimental validation namely, 1. hollow annular ring, 2. annular ring with a solid cylinder and 3. solid cylinder. Experimental and numerical simulations are performed for a 2-pole in house built 15 kW linear electromagnetic stirrer (EMS). It is observed for a supply current of 200 A at 30 Hz the force densities in the hollow annular ring is 67% higher than the equivalent solid cylinder. The same values are 33% for annular ring with a solid cylinder. Force density variation with supply frequency and current are also reported. Numerical simulations using finite element model are validated with experimental results.

In vivo contact kinematics and contact forces of the knee after total knee arthroplasty during dynamic weight-bearing activities

Analysis of polyethylene component wear and implant loosening in total knee arthroplasty (TKA) requires precise knowledge of in vivo articular motion and loading conditions. This study presents a simultaneous in vivo measurement of tibiofemoral articular contact forces and contact kinematics in three TKA patients. These measurements were accomplished via a dual fluoroscopic imaging system and instrumented tibial implants, during dynamic single leg lunge and chair rising–sitting. The measured forces and contact locations were also used to determine mediolateral distribution of axial contact forces. Contact kinematics data showed a medial pivot during flexion of the knee, for all patients in the study. Average axial forces were higher for lunge compared to chair rising–sitting (224% vs. 187% body weight). In this study, we measured peak anteroposterior and mediolateral forces averaging 13.3% BW during lunge and 18.5% BW during chair rising–sitting. Mediolateral distributions of axial contact force were both patient and activity specific. All patients showed equitable medial–lateral loading during lunge but greater loads at the lateral compartment during chair rising–sitting. The results of this study may enable more accurate reproduction of in vivo loads and articular motion patterns in wear simulators and finite element models. This in turn may help advance our understanding of factors limiting longevity of TKA implants, such as aseptic loosening and polyethylene component wear, and enable improved TKA designs.

Size effects in the axial tearing of circular tubes during quasi-static and impact loadings

An experimental investigation is reported into the size effect for thin-walled mild steel circular tubes which are axially split and then plastically rolled up on a conical mandrel when their upper ends were pressed by the cross-head of a testing machine or struck by a heavy mass with impact velocities of 9.0 and 13.5 m/s. The test tubes have scale factors of one, two and four. Deviations of 11–57 percent from the elementary geometrically similar scaling laws are observed in the maximum permanent axial deflection, u max, tearing length, Δ a, diameter of plastically deformed curls, d, specific energy absorbed, w, and average axial force, F ave. The material strain rate hardening effect is the main factor causing these deviations. A new scaling law including material strain rate hardening effect is suggested.