Clamping Force Research Articles

Can electrophysiological information reflect the response of mangrove species to salt stress? A case study of rewatering and Sodium nitroprusside application

ABSTRACT The changes in plant life behaviors and water status are accompanied by electrophysiological activities. In this study, the theoretical relationship between clamping force (CF) and leaf resistance (R), capacitive reactance (XC), inductive reactance (XL), impedance (Z), and capacitance (C) were exposed as 3-parameter exponential decay and linear models based on bioenergetics, respectively, for mangrove species. The intracellular water metabolism parameters and salt transport characteristics were also determined based on mechanical equations with influences of Sodium nitroprusside (SNP) and rewatering (RW). The results show that the inherent capacitance and effective thickness could better represent Aegiceras corniculatum (A. corniculatum) species, and inherent resistance and impedance show obvious effects on Kandelia obovate (K. obovate) species at different salt levels. SNP application shows positive effect on different salt-resistance capacities of A. corniculatum, while K. obovate perform better in RW phase at high salt level. These outcomes indicates that K. obovate is more salt-resistant because RW process is consistent with actual situation, and response of A. corniculatum at high salt stress is irreversible, even in RW. It is concluded that the electrophysiological parameters could be used for the determination of salt-resistant capacities, which gave more enhanced and reliable information of mangroves’ life activities.

Design and Analysis of Distortion in Welding Fixture for Frame Assembly

This paper focuses on the Design and Analysis of Welding Fixture for Anti-vibration under carriage Bogie Frame Assembly for Compact Track Loader. The application of a Bogie assembly is to offering smoother transitions over uneven terrain, and the ability to travel at higher speeds with better materials retention. Due to the nature of welding process involving localized heat generation from moving heat source, rapid heating in the welded structures, and subsequent rapid cooling, problems such as residual stresses and distortions of welded structures remain important challenges in the industry. To assemble the respective child parts and to meet the required tolerances on the bogie frame assembly welding fixture specially designed with the help of CAD Software. In practice, welding distortion creates unwanted effects on manufacturing accuracy, appearance and strength of welded parts. By using Finite Element Analysis (FEA), the analysis is carried out to find welding distortion of Bogie Frame assembly. Along with optimum clamping force has been calculated which required for controlling the welding distortion. After successful Design and Analysis, the Welding fixture has been manufactured and has been implemented at shop floor. This welding fixture used for accurate assembly of the child parts with required tolerances , as well as helps in reduction of production loss and also manufacturing lead time for welding, positioning and holding parts.

Design criteria study and simulation for underactuated symmetric pinching mechanism of pinch roll machine in high-speed wire rod product line

Inspired by the underactuated robotic hand mechanism and its feature of shape adaptive and compliant envelop grasping, the paper presents an underactuated symmetric pinch mechanism to solve the problem of pinch rollers idle and slipped or pinched too tightly. Pinch roll machine is a key device in the high-speed wire rod product line. It is usually designed with actuated symmetric pinch mechanism. The paper considered the pinching and conveying condition of linear objects and discussed the possibility of the underactuated symmetric pinch mechanism to be applied in the pinch roll machine for the first time. Three kinds of underactuated symmetric pinch mechanism solutions are presented. A displacement can be generated at the underactuated joint when the symmetric synchronous pinch action is implemented. The spring system can buff the instantaneous clamping force to reduce the dynamic impact of clamping force. Suitable design criteria are deduced from statics and kinematics analysis. In the process of pinching and conveying wire rods, the contact force is required to be kept at a constant value when the size of wire rods changes. Thus, it can protect the rod from being damaged while pinching and conveying and it can avoid the fatigue damage caused by excessive pinching impact force. Then, the pinching and conveying conditions of four different kinds of variable diameter wire rods are analyzed through 3D modeling and motion simulation experiments. Simulation results show that the proposed underactuated pinching and conveying mechanism can satisfy shape adaptive pinching and conveying irregular long-shaped wire rods. The research method is novel and feasible. The design result will be beneficial to improve the service life of the pinch roll machine.

Optimization parameter for microgripper based on triple-stair compliant mechanism using GTs-TOPSIS

In manipulating the assembly of micro-components, the symmetrical microgripper mechanism often causes destruction, damaging those components during manipulation, due to the phenomenon of non-uniform clamping force output from the clamp. From this disadvantage, a new asymmetric microgripper structure is proposed with stable output clamping force. The asymmetric microgripper structure will have a smaller output displacement than that of the symmetric structure. Therefore, to increase the output displacement gain, a flexible hinge with a triple-stair half-bridge-style mechanism (TSBM) is adopted to design the amplifier of the asymmetrical microgripper. The finite element method is applied to analyze the displacement and stress. The optimization process is performed based on the geometric parametric properties of the structure. Using the technology for order preference by similarity to ideal solution (TOPSIS) based on the Grey relationship analysis (GRA), we obtained the maximum displacement output and minimum stress. Results show that the maximum output displacement is 5,818 mm, and stress after analysis is 2,432 MPa. The test is conducted to verify the optimal results and the effectiveness of the optimization method. Finally, experimental experiments were performed, with a 4.8% difference from the FEA results. The results from the experimental test verify that the microgripper’s maximum displacement amplification ratio is approximately 58.2 times.

"Optimal Clamping Force of Ultra High Molecular Weight Polyethylene Cable is 15 kgf"

"Optimal Clamping Force of Ultra High Molecular Weight Polyethylene Cable is 15 kgf"

Welding simulation of railway bogie frame side beam: Analyses of residual stresses, clamping forces, distortion and prediction of fatigue S-N curves

This paper presents numerical analyses of a welding simulation of a bogie frame side beam. The simulation is based on an analytical thermal model coupled with a non-linear structural finite element model using shell elements enabling the welding simulation of large structures. The predicted clamping forces, distortions, and residual stresses for different clamping conditions and plate thicknesses are analysed in terms of manufacture. A new fatigue model based on the endurance limit approach is proposed using residual stresses to predict the S-N curves. The predicted S-N curves with the proposed model showed close correlation with the S-N curves for class F and class F2 welds of the BS7608 standard, demonstrating its validity and potential use in design.

Effect of clamping force on distortion of the optical surface of monochromators during assembly.

As Diamond Light Source embraces the move towards becoming a fourth-generation light source its optics will be required to perform under increasingly demanding conditions. Foremost amongst these conditions will be the increasing power densities the optics are subjected to and the reducing real estate they have to perform in. With these new challenges comes the need for greater understanding of how optics are assembled and how consistently the activity is carried out. In this paper, the effect of bolt pretension during assembly of monochromators on distortion of the optical surface is investigated through numerical simulation. The results reveal skewed convex distortion of the optical surface in the meridional direction when uneven clamping force is applied, highlighting the importance of taking the potential for distortion of the optical surface due to clamping force into consideration.

Research on Clamping Force Control of CVT for Electric Vehicles Based on Slip Characteristics.

The low mechanical efficiency of metal belt’s continuously variable transmission (CVT) limits its application in new energy vehicles. To further improve CVT efficiency and reduce the energy consumption of electric vehicles (EVs) with CVT, this paper proposes a pure electric CVT configuration and a clamping force control strategy. The slip characteristics of CVT are obtained through a bench test, the dynamic model of CVT slip is established, and a clamping force fuzzy control strategy is designed. The strategy is studied by simulation under extreme conditions and standard driving cycles. The simulation results show that the proposed clamping force control strategy has good adaptability. Under extreme conditions, this strategy can ensure that CVT does not undergo macro slip, while reducing the clamping force by 12.86–21.65%. Energy consumption per 100 km is 14.90 kWh in NEDC, which is 6.67% lower compared with the traditional strategy. CVT average efficiency and average transmission efficiency increased by 3.71% and 6.40%. The research results demonstrate that adjusting the CVT clamping force through fuzzy control based on the slip rate can improve the CVT efficiency and energy economy of EVs, which provides a certain reference for CVT clamping force control strategy development and the application of CVT on EVs.

Design and Optimization of a Boat-Bottom-Shaped Transplanting Device for Sweet Potato (Ipomoea batatas) with Low Seedling Damage Rate

A transplanting manipulator and a transplanting conveyance device were devised to address the problems with current sweet potato transplanters, which cannot properly finish boat-bottom-shaped transplanting and have a high seedling damage rate. The ground wheel transmits power to the two devices in a specific transmission ratio to ensure their synchronous movement and avoid accumulated deviations. We selected the transplanting manipulator’s parameter combination that satisfies the optimal transplanting trajectory by the VB program. To avoid damage to the seedlings during clamping, the clamping force is only provided by the spring through the structural design. Combined with the agronomic requirements of boat-bottom-shaped transplanting and the characteristics of soil resistance during the transplanting process, the transplanting depth and crank rotation speed were selected as test factors. The qualified rates of node depth in the seedling middle (QRNDSM), the qualified rates of seedling root depth (QRSRD), and the qualified rates of stalk length into the soil (QRSLS) were established, and Design-Expert was used for the quadratic regression and orthogonal combination tests to optimize the factors. The results of the verification tests reveal that when the transplanting depth is in the range of 45.56 to 58.26 mm and the crank rotation speed is in the range of 39.39 to 43.45 rpm, the maximum QRNDSM is 94.91%, the maximum QRSRD is 95.42%, and the maximum QRSLS is 94.93%, which satisfies the industry standards. Research into sweet potato transplanting can benefit from this work, especially in the direction of sweet potato boat-bottom-shaped transplanting.

Temperature effect on mechanical performances and failure mechanisms of single-lap countersunk-screwed CFRPI-metal joint

This paper seeks to experimentally and numerically probe temperature effects on mechanical performances and failure mechanisms of single-lap countersunk-screwed CFRPI-metal joints. Quasi-static tension tests were performed on single-lap countersunk-screwed CCF300/AC721-30CrMnSiA joints at −40 °C, −25 °C, RT (room temperature), +250 °C and +350 °C, and temperature impact was analyzed and discussed from experimental results. By considering thermal–mechanical interaction, non-linear shear constitutive relationship and complicated failure modes, an improved PDM (progressive damage model) was devised to simulate mechanical performances and failure mechanisms of single-lap countersunk-screwed CCF300/AC721-30CrMnSiA joints, and the predictions agree well with the experimental results. Based on numerical results, it is demonstrated that temperature effect on joint performances arises from the changes in clamping and friction forces and in interlaminar properties of material with temperature, and delamination around screw hole is likely the primary reason for final failure of joint.

Experimental Validation of a Novel Concept to Reduce Optical Surface Wave Front Errors by Using Deformable Bushes at Opto-Mechanical Interfaces

One of the major objectives of the optomechanics is to support large optics required for the purpose and also to maintain high dynamic stability in operation. This requirement calls for more number of supports, to support large optics. While addressing this issue, the mounting system tends to become non-kinematic and distorts the optical surface and leads to poor image quality. The distorted optical surfaces bring in increased RMS surface wavefront errors which will result in poor image quality. In this context, a new concept is proposed in our previous publication ( Nagabhushana et al., 2021 ) which involves introduction of deformable bushes at the optomechanical interfaces. These are deformed by applied clamping forces and also enabling all degrees of freedom (DOF) to be arrested. This also ensures that the clamping force in axial DOF is limited to a minimal value. This technique enables to arrest of axial DOF without exerting the clamping force on the optomechanical assembly there by reduces optical aberrations and improves the mounting system’s dynamic stability. This is because deformable bushes absorb all the clamping forces and the strain has no impact on the mount and therefore does not lead deformation of the optical surface. The clamping forces are simulated by Finite Element (FE) methods. Further, in this paper, the concept is verified and validated by experiments. The simulation results are observed to be in close correlation with experiment results. Improved stability is also observed by additional constraints introduced to optomechanical mounts with no compromise in wavefront errors.

The Effect of Clamping Force on the Wear Behavior of a Steam Generator Tube

Anti-vibration bars (AVBs) are essential components of a steam generator (SG) and are used to prevent steam generator tubes (SGTs) from vibrating intensely because of flow-induced vibration. However, the contact force generated at contact surfaces between AVBs and tubes can change the natural frequency and wear behavior of the tube. Contact force is represented by clamping force in this study. Considering the effect of the clamping force on the natural frequency and sliding distance of SGT, dynamic wear behavior under different clamping forces was analyzed based on the finite element method, and the natural frequency of the tube was measured in the present work. Moreover, the wear experiment was conducted at room temperature to verify the conclusions of dynamic behavior analysis. The increase in clamping force reduces the sliding distance of SGT, and wear depth affected by both clamping force and sliding distance also decreases.

Multi-scale Crystal Viscoplasticity Approach for Estimating Anisotropic Steady-State Creep Properties of Single-Crystal SnAgCu Alloys

Creep can have a significant impact on the reliability of Sn-based solder alloys even at room temperature because of their relatively low melting temperatures. SnAgCu (SAC) solder joints used in electronic packaging typically consist of only a few highly anisotropic grains, which consist of Sn dendrites embedded in a near-eutectic Sn-Ag component. The unique grain structure of each joint leads to stochastic variations in the thermomechanical response of such joint. Therefore, grain-scale testing and modeling are recommended to better characterize the anisotropic behavior and to estimate the influence of stochastic variability of grain structure on the viscoplastic response of the joint. This work aims to investigate the anisotropic steady-state creep behavior of single-crystal SAC solder joints. The orientation-dependent viscoplastic behavior of individual SAC grains is modeled with a multi-scale crystal-viscoplasticity approach for representing the relevant dislocation mechanics. The response predicted by the crystal viscoplasticity model is then captured in an equivalent homogenized continuous-scale constitutive model (Hill-Garofalo formulation).This modeling strategy was implemented in numerical simulations, as an illustrative example, to analyze the behavior of single-grain solder joints subjected to combined steady compression (from heat-sink clamping force) and thermal cyclic loading. The cyclic ratcheting in the presence of the steady compressive force causes: (i) transverse expansion of the solder ball, potentially leading to eventual short circuits; and (ii) cyclic fatigue damage leading to eventual failure of the solder joint. The proposed grain-scale modeling approach is shown to be able to address the stochastic variability of both these damage mechanisms, as a function of grain orientation. The present methodology can be used to predict the realistic behavior of solder joints, based on their microstructure, and provide valuable insights for their reliability analysis.

T-Maps-Based Tolerance Analysis of Composites Assembly Involving Compensation Strategies

Abstract Clamping force and shimming are two important compensation processes in the composite assembly. Their effects on variation propagation should be investigated in tolerance analysis. The paper presents a tolerance analysis method for composites assembly based on the T-Maps method, mainly concerning the anisotropic variations accumulation and propagation where there is the clamping force modification and the shimming. Variations of the composite parts in different directions are represented by the T-Maps. Since the different axial deviations are represented in the same Euclidean point-space, the T-Maps-based tolerance analysis of the composite parts assembly provides more accurate and reliable results. Compensation processes, the clamping force, and the shimming, on assembly tolerance synthesis of the composite parts, are analyzed clearly in the T-Map. This procedure is found to be effective for the anisotropy-oriented assembly tolerance analysis, especially concerning about effect of the clamping force and the shimming on variations accumulation and propagation. The assembly of an aircraft composite elevator is considered to demonstrate the effectiveness of the T-Maps-based method. The procedures outlined in the paper are quite general and can be used for assembly tolerance analysis of anisotropic parts.

Machine Learning Techniques for Increasing Efficiency of the Robot's Sensor and Control Information Processing.

Real-time systems are widely used in industry, including technological process control systems, industrial automation systems, SCADA systems, testing, and measuring equipment, and robotics. The efficiency of executing an intelligent robot’s mission in many cases depends on the properties of the robot’s sensor and control systems in providing the trajectory planning, recognition of the manipulated objects, adaptation of the desired clamping force of the gripper, obstacle avoidance, and so on. This paper provides an analysis of the approaches and methods for real-time sensor and control information processing with the application of machine learning, as well as successful cases of machine learning application in the synthesis of a robot’s sensor and control systems. Among the robotic systems under investigation are (a) adaptive robots with slip displacement sensors and fuzzy logic implementation for sensor data processing, (b) magnetically controlled mobile robots for moving on inclined and ceiling surfaces with neuro-fuzzy observers and neuro controllers, and (c) robots that are functioning in unknown environments with the prediction of the control system state using statistical learning theory. All obtained results concern the main elements of the two-component robotic system with the mobile robot and adaptive manipulation robot on a fixed base for executing complex missions in non-stationary or uncertain conditions. The design and software implementation stage involves the creation of a structural diagram and description of the selected technologies, training a neural network for recognition and classification of geometric objects, and software implementation of control system components. The Swift programming language is used for the control system design and the CreateML framework is used for creating a neural network. Among the main results are: (a) expanding the capabilities of the intelligent control system by increasing the number of classes for recognition from three (cube, cylinder, and sphere) to five (cube, cylinder, sphere, pyramid, and cone); (b) increasing the validation accuracy (to 100%) for recognition of five different classes using CreateML (YOLOv2 architecture); (c) increasing the training accuracy (to 98.02%) and testing accuracy (to 98.0%) for recognition of five different classes using Torch library (ResNet34 architecture) in less time and number of epochs compared with Create ML (YOLOv2 architecture); (d) increasing the training accuracy (to 99.75%) and testing accuracy (to 99.2%) for recognition of five different classes using Torch library (ResNet34 architecture) and fine-tuning technology; and (e) analyzing the effect of dataset size impact on recognition accuracy with ResNet34 architecture and fine-tuning technology. The results can help to choose efficient (a) design approaches for control robotic devices, (b) machine-learning methods for performing pattern recognition and classification, and (c) computer technologies for designing control systems and simulating robotic devices.

Design and validation of a sheet metal clamping system for additive manufacturing and post-processing

Automated clamping for post-processing of mass-customized parts is a challenging step in the laser powder bed fusion (LPBF) process chain. In this study, a novel modular sheet metal clamping system was developed that uses disposable sheet metal profiles as a universal interface for the LPBF, robotic handling, and milling processes. Based on a fundamental investigation of hybrid additive manufacturing, the sheet metal clamping system was designed to use the same interface for the LPBF and milling processes. Subsequent an end-to-end validation was performed for the entire process chain. The concept of the sheet metal clamping system gives milling tools access to a part on five to six sides. Further, the part can be accessed from the top and bottom sides, and simplifying the removal of LPBF supports. No clamping forces are induced in the LPBF part, which is especially important for filigree structures. The sheet metal clamping system’s underlying concept could be adapted to automating the LPBF process chain for applications such as prosthetic dentistry.

CNN-GRU network-based force prediction approach for variable working condition milling clamping points of deformable parts

Improper clamping is one of the major causes of part deformation. Improving the fixture arrangement through force analysis of clamping points is an effective means to suppress or improve machining deformation. However, the existing research focuses on the monitoring and off-line optimization of the clamping point force, which has a certain lag on the machining deformation control, and it is difficult to predict the clamping point force due to the time-varying coupling effect of multiple factors such as process parameters, cutting force, and clamping point force in the machining process. Inspired by the excellent performance of convolutional neural networks and gated recurrent networks in feature extraction and learning of temporal association laws, this paper proposes a CNN-GRU-based method for predicting the force state of clamping points under variable working conditions. Firstly, a force prediction model of clamping point during milling process with variable working conditions is established. Secondly, a convolutional neural network is designed to extract the features of dynamic coupled machining conditions. Then, a network of gated recurrent units is constructed to learn the temporal correlation law between the machining conditions and the forces on the clamping points to achieve force prediction of the clamping points during machining. Finally, it was verified by the milling process of the piston skirt. The results show that CNN-GRU can effectively predict the clamping force. In addition, CNN-GRU has higher computational efficiency and accuracy compared with CNN-LSTM, CNN-RNN and CNN-BP.

Stable Characteristics Optimization of Anti-Symmetric Cylindrical Shell with Laminated Carbon Fiber Composite.

This paper proposes a multi-objective optimization model for anti-symmetric cylindrical shell in the bionic gripper structure. Here, the response surface method is used to establish multiple surrogate models of the anti-symmetric cylindrical shell, and the non-dominated sorting genetic algorithm-II (NSGA-II) is used to optimize the design space of the anti-symmetric cylindrical shell; the design points of the anti-symmetric cylindrical shell are verified by experimental methods. The optimization goals are that the first steady state transition load (the transition process of the bionic gripper structure from the open state to the closed state) of the anti-symmetric cylindrical shell is minimized, and the second steady state transition load (the transition process of the bionic gripper structure from the closed state to the open state) is the largest. At the same time, in order to prevent stable instability caused by stress concentration in the second steady state of the anti-symmetric cylindrical shell, the maximum principal plane stress is given as the constraint condition. The validity of the optimization results is verified by finite element and experimental methods. Due to the stable transition load of the anti-symmetric cylindrical shell being significantly larger than that of the orthogonal laminated plate, therefore, the anti-symmetric cylindrical shell has potential application prospects in the application of deformable structures and bionic structures that require composite functions such as having light weight, high strength, and large clamping force. The novelty of this paper lies in the multi-objective optimization of the application of the antisymmetric bistable cylindrical shell in the bionic gripper structure.

Optimizing the Performance of an Automatic Clamping System for Gear-Shaping Machines

Gear shaping machine is used to manufacture both external and internal gears. It is a semi-automatic controlled machine in which all machining operations are carried out by automatically indexing, where loading and unloading of a work piece are performed manually. Also, the operator needs to wait for unloading, until the entire machining operation to be completed. Hence manufacturing cost is increased due to labor charges and overall machining time. Our proposed technique is to minimize the total cost of manufacturing, it is planned to eliminate the manual operation in loading and unloading of each component. Full automation of shaping machine requires storing device, a transfer device, automatic clamp device, and sequence controlling system. Full automation of shaping machine requires storing device, a transfer device, automatic clamp device, and sequence controlling system. The objective of this paperwork is to design a pneumatic clamping device needed for an automatic loading system, to hold the work piece the revolving table using Pro-E Wildfire software. Then calculate the clamping force theoretically for various pressure ranges and find the suitable working pressure. Also, static analysis of all designed components is performed to validate their strength using Ansys software. Based on the dimension, all parts are manufactured and assembled to test their performance.

A Comparative Analysis of Brake-by-Wire Smart Actuators Using Optimization Strategies

Since the automotive industry is shifting towards electrification, brake-by-wire technologies are becoming more prevalent. However, there has been little research comparing and optimizing brake-by-wire actuators in terms of their energy expenditure and response time. This paper investigates the comparison of three different smart brake-by-wire actuators, Electro-Hydraulic Brakes (EHB), Electro-Mechanical Brakes (EMB), and Electronic Wedge Brakes (EWB), first by defining an objective metric and then using both linear and nonlinear optimization techniques. Modeling of the actuators is performed using the bond graph method. Then, the controllers are designed using a robust control strategy, Youla parameterization. After designing the controllers, two types of optimization are performed on the actuators. Optimizations are performed in two ways: 1. by linearizing the plants and optimizing using their transfer functions and 2. by nonlinear optimization of the plants in the closed-loop following a specific clamp force target. The objective metrics or the cost functions for these optimizations are chosen to be the energy usage of the plants during the closed-loop operation, maximum power requirement, and their dynamic responsiveness. Using this optimization framework, we can show a significant improvement in the energy usage of the actuators and slight improvements in their responsiveness. In the end, the actuators are compared in terms of their energy usage for sets of initial and optimized physical parameters.