جستجوی مقالات مرتبط با کلیدواژه "force" در نشریات گروه "مکانیک"

The significance of sheet metal drilling within industrial applications is widely recognized, particularly for its critical role in creating durable connections in sheet components. This process, especially when implemented through friction drilling, not only minimizes material waste by generating connecting flanges bush shape but also enhances the robustness of the connections. In this study, we used the ABAQUS finite element software (FEM) to simulate and design the friction drilling process on sheets of three different thicknesses, employing three rotational speeds and three feed rates. The analysis was conducted using Design Expert statistical software, which integrated response surface methodology (RSM) and data analysis to thoroughly investigate the process forces. Aluminum AA 7075 was selected for the study due to its extensive use in the automotive, manufacturing, military, and aerospace organizations, highlighting its industrial relevance. The findings suggest that optimizing the machining force leads to more favorable conditions within the process. The optimal parameters were determined to include the highest rotational speed, the lowest feed rate, and the smallest sheet thickness. These conditions promote higher temperatures that facilitate better material flow. An increase in thickness was also found to correlate with higher temperatures. Additionally, the study addressed the significant industrial challenge of residual stresses and their effects on component defects, a topic not previously explored through finite element simulations in this context. This research contributes new insights into the implications of residual stresses in various directions for friction drilling processes.

One of the most significant and applicable machining processes in surgeries and medical engineering is the bone drilling process. In this process, it is intended to minimize the axial force on the bone tissue during surgery. To reduce force, different methods have been considered; including the use of a variety of lubricants, ultrasonic oscillations, material replacement, tool geometry, and also the use of coated tools. The purpose of this paper is to investigate the effect of a specific type of nano coating on steel tool, and to investigate the effect of effective input parameters on force behavior in orthopedic drilling with medical requirements in mind. In this study, the polymeric material of poly-methyl-meta-carylate (PMMA), which has similar properties to the bone, was selected; and by creating titanium nitride nano coating on the tool, the effect of tool rotational speed, feed rate, and the tool diameter on the drilling process force have been extracted using the design of experiment by the response surface method, modeling and second-order linear regression equation governing the model. The optimum values of each input parameter are also presented in order to achieve the minimum and the best amount of force created during orthopedic drilling. The results show that the creation of titanium nitride nano coating reduces the force by 40 percent. Also, the axial force with the maximum cutting speed, the minimum feed rate, and in the tools with smaller diameters has been significantly reduced.

Shape memory polymers are a type of smart materials that can recover their original shape when exposed to external stimuli including temperature, magnetic field, light, and electric field. One of the most widely used of these polymers is thermalresponsive shape memory polymers. These polymers have advantages such as a high percentage of shape recovery and low cost and using them results in reducing complex mechanisms that lead to reducing the weight and volume of the systems. Thermalresponsive shape memory polymers have been used in many fields, including medicine, robotics, mechanics, and aerospace and have led to great changes. This paper aims to study thermal-responsive shape memory polymers behavior and their different applications. In fact, by investigating the thermomechanical cycle, constitutive models, different kinds of shape memory effect, different applications, their future, and challenges of these polymers including low recovery force and its solution and preparation of various tables from recent researches, these materials have been comprehensively studied. Due to the unique properties of these polymers and the effort to overcome their limitations, they will become a candidate for many self-assembled mechanical actuators in the future.

This paper presents a novel Contactless Hybrid Static Magnetostrictive Force-Torque sensor using Galfenol. Initially, the sensor's design principles in axial force and torque measurements are described. The magneto-mechanical properties of used materials, such as B-H curves and magnetic permeabilities are measured under various mechanical preloads and magnetic fields and improved in some cases. These properties are used in finite element method. The sensor is evaluated numerically using COMSOL Multiphysics® software based on the obtained experimental results. Afterward, the sensor is fabricated based on finite element method results and experimentally tested in different electrical currents and excitation frequencies. Sensitivity, repeatability and linearity errors are presented separately in force and torque measurements in optimal operating condition of the sensor. Then, the finite element method results are verified with the experimental results. Finally, the performance characteristics of the sensor in optimal conditions are presented and it is found that the sensitivity increases while increasing the electrical current (or magnetic field) and frequency. The maximum sensitivities for axial load and torque measurements are obtained at 0.7349 mV/kgf and 2.24 mV/N.m, respectively.

In the wind tunnels, the balance measurement instrument is used to measure six components of force and moment on an airplane model. The balance of measurement consists of two parts of the balance structure and electronic equipment. In this research, a mechanism with flexible hinges is designed to achieve the desired configuration of the balance structure. In the process of designing the geometric structure of this mechanism, an effective arrangement has been implemented for the six load cell - flexure columns. The advantages of flexible hinges in comparison to conventional hinges are the absence of friction, compactness and its linear behavior. The reaction effects of the components of force and moment on each six load cell - flexure columns created the coupling errors. One of the main sources of this kind of error is related to the structure of the balance mechanism. The reason for this type of error is the inadequacy of the axial flexibility to the lateral flexibility of the columns. The aim of this research is to optimize the design of the flexible mechanism in order to achieve the minimum coupling error of the structure. For this purpose, hinge design considerations and analytical equations of the flexible mechanism have been extracted. The design of the balance mechanism is optimized by creating a structure coupling error matrix. To validate the analytic equations and results, the problem is compared with the finite element analysis. The results indicated that the measurement errors decrease in the measurement of six components of force and moment of balance.

Bone drilling process is indispensable in orthopedic surgeries and treating bone breakages. It is also very important in dentistry and bone sampling operations. Therefore, bone drilling is one of the most important, common and sensitive processes in biomedical engineering field. Orthopedic surgeries can be improved using robotic bone drilling systems and also mechatronic bone drilling process can be promoted using automatic drilling machines and surgery-assisting robots. Furthermore, imposing higher forces to bone might lead breaking or cracking and consequently serious damage in bone. In this paper a mathematical second order linear regression model is introduced to predict process force behavior during bone drilling process as a function of tool drilling speed, feed rate, tool diameter and effective interactions. Design of experiments using response surface methodology is followed. Then second linear governing equation is assigned to the model and its accuracy is evaluated. Later, Sobol Statistical sensitivity analysis is used to ascertain the effect of process input parameters on process force. Results show that among all effective input parameters tool rotational speed, feed rate and tool diameter have the highest influence on process force respectively. The behavior of each output parameters with variation in each input parameter is further investigated.

Some appropriate characteristics like corrosion resistance, higher strength, and higher thermal and electrical conductivities cause that applications of clad sheets have been recently increased significantly in industries like production of electrical and electronic switches. In this paper, an analytical solution based on the slab method analysis is presented to investigate the asymmetrical rolling of unbonded clad sheet. Roll radii, roll speeds, friction condition between surfaces, as well as the yield stress ratio of material of sheets are parameters of the asymmetrical rolling that considered in this paper. The non-uniformity of the shear stresses and the uniformity of the normal stresses at the vertical sides of each slab across the portion of the deformation material is taken into account through the plastic region. The behavior of material in plastic region is considered to be rigid-perfectly plastic. The main goal of this paper is to investigate the simultaneous effect of back and front tension and asymmetrical parameters on normal stresses and pressure distributions along the contact area of rolls and sheets for the first time in order to decrease pressure and force in the process. The effects of these parameters on the positions of the neutral points on the upper and lower rolls are also investigated. Moreover, the maximum back and front tensions to avoid slipping of the sheet are determined. The results show that by applying the proper amounts of tensions to the sheet at the entry and exit of deformation zone, pressure and force values could be reduced, considerably.

One of the most important machining processes in the field of orthopedic surgeries and biomedical engineering is the drilling process. Applying excessive forces on the bone tissue, it can be caused cracking and damage bone tissue during the drilling process. In this paper, it is produced an improved analytical model based on early work done by Bono and Ni, Chandrasekharan, and Lee to predict the thrust force in the bone drilling process. In this model, the cutting action at the drill point is divided into three regions: the primary cutting lips, outer portion of the chisel edge (the secondary cutting edges), and inner portion of the chisel edge (the indentation zone). All three regions have been investigated for the cutting process by the analytical model. In order validating the model, some experiments performed on the fresh bovine bone. Feed rate and rotational speed are adapted as the effective parameter in the drilling process, The statistical model to obtain the mathematical model and provide interaction diagrams of input variables experiments, to response surface methodology and experimental investigation of bone drilling have been offered. Comparing the analytical model and experimental results show good agreement. From both analytical model and experiments, it is can conclude that with decreasing feed rate and increasing rotational speed, thrust force on the bone tissue decreases.

The aim of this research is to dynamically investigate the effect of high-heel shoes on the amount of internal forces and torques produced in the lower body joints (hip, knee, and ankle joints) during walking. To do so, the gait analysis of the subject, in two states of walking barefoot and with high-heel shoes, has been conducted in a Musculoskeletal Research Center and then the required kinematic data including rotation matrices, angular velocity and angular acceleration of lower legs using kinematic analysis of legs have been derived. Also, the ground reaction forces have been measured using a force plate installed in the lab and by presenting a 3D dynamic model of lower legs and solving the inverse dynamic problem of model, forces and moments of the joints for two above modes during stance phase of a gait cycle have been calculated. Based on obtained results from investigation of dynamic effect of high-heel shoes during walking, variations of internal joint forces have not been salient. However, internal joint moments in state of gait with high-heel shoes respect to barefoot walking, have been had considerable increase. According to the results, long-term wear of high-heel shoes can lead to damage of lower body joints, especially the knee joint, as well as driving muscles of these joints.

Bone drilling process is the most prominent process in orthopedically surgeries and curing bone breakages. It is also very common in dentistry and bone sampling operations. Due to complexity of the material that is machined, bone, and the sensitivity of the process, bone drilling is one of the most important, common and sensitive processes in biomedical engineering field. Developed a three-axis robotic bone-drilling system and mechatronic bone-drilling tools improved the orthopedic operations. Furthermore, imposing higher forces to bone might lead breaking or cracking and consequently serious damage in bone. In this paper a mathematical second order linear regression model is introduced to predict process force behavior during bone drilling process as a function of tool drilling speed, feed rate, tool diameter and effective interactions. This model can predict carefully force behavior during bone drilling within the acceptable range. Moreover, applying design of experiments, modeling and optimization of effective parameters using response surface method in bone drilling process optimized drilling speed, feed rate and tool diameter were obtained to minimize force. Results show that to minimize force increasing the drilling speed would decrease the thrust force, whereas decreasing the feed rate and tool diameter would decrease the Thrust force.

In this study, 3D 8inite element simulation of reaming process has been carried out on the hard steel. The cutting parameters in the simulation process were selected based on the optimum experimental results which lead to the smaller cutting forces, lower vibration of the reaming tool and better surface quality. This simulation was used to predict cutting forces as one of the most important reaming output variables. Simulation of material removal process was performed by commercial finite element software SFTC DEFORM-3D and using the explicit Lagrangian code. In addition, some empirical experiments were done on the hardened D2 tool steel workpieces to 8ind the optimum reaming condition and validation of finite element model. Cutting parameters including feed rate and cutting speed were changed and cutting forces were measured, experimentally. The results showed that the numerical results have a good consistency with the experimental one and average difference of 10% was seen. Finally, the effect of input parameters on the cutting force at the simulation and experimental test were investigated. It was seen that the cutting forces error is reduced between two analyses by increasing the feed rate. This indicates that the meshes with higher quality and density are required in lower removal rate.