With the development of Chinas high-end manufacturing industries, the demands for thin-walled components in many industrial fields such as aerospace were increased dramatically. The high-speed forming characteristics, traditional EMF was successfully applied to the production of thin-walled components of some key lightweight materials. However, due to the limitations of forming coil and discharge equipment, it was difficult to process large-scale and complex structure parts. In the past decade, incremental EMF technology was developed and gradually applied to the large thin-wall components processing, where a large number of research results were emerged. On the basis of briefly describing the principle and characteristics of EMF technology, the existing incremental EMF technology was divided into two categories according to the processing form: incremental electromagnetic composite forming and incremental electromagnetic direct forming. The research status of each processes was expounded from the aspects of basic principle, technical scheme and application results. Thus the main problems existing in the incremental EMF technology were analyzed, then the future development prospects and research direction of the incremental EMF technology were prospected.

In order to accurately describe the deformation behaviors of lightweight thin-walled components during ultrasonic vibration-assisted forming, ultrasonic vibration normal excitation-assisted uniaxial tensile experiments were carried out with TU1 oxygen-free copper and 316L stainless steel. Considering the ultrasonic vibration softening effects, an ultrasonic vibration Johnson-Cook model was developed by introducing a new ultrasonic softening function. A subroutine was developed and embedded into finite elements for simulation, and was validated by comparison with unidirectional tensile and curling experiments. The results show that the numerical model may effectively capture the ultrasonic vibrational softening behaviors of the materials with an average absolute percentage error as low as 0.97%. Although different materials have different sensitivities to ultrasonic vibration, the ultrasonic softening rates all follow an Allometricl functional relationship with the ultrasonic energy field density.

Creep aging tests were conducted on the 2195 Al-Li alloys under various stress conditions at temperatures of 180 ℃, 190 ℃, and 200 ℃ respectively. Constitutive equations were derived using MATLAB software and incorporated into the nonlinear finite element software MSC.Marc to build a finite element model for the creep aging forming of 2195 Al-Li alloy spade segments. The model utilized time, stress, and temperature as input parameters, with the springback radius being the critical output parameter. To enhance the accuracy and efficiency of predictions, a comparative analysis of various machine learning regression models was conducted, leading to the selection of the ridge regression model as the predictive tool, which facilitated the rapid and precise prediction of the springback radius under diverse processing conditions. The high predictive accuracy and practical utility of the model were validated through 1∶1 experimental verification, demonstrating a relative error of 0.9% between the experimental components springback profile and the target profile. 

Non-eddy current electromagnetic forming is a new type of electromagnetic forming process, which realized high-speed deformation of the workpieces by directly applying pulse current on the metal workpieces instead of induced eddy current. The speed reached 102 m/s and the strain rate was as high as 103 s-1, which did not have a complex coil structure and the electromagnetic force was more uniform. For the 5052-O aluminum alloy sheets based on the non-eddy current electromagnetic forming experiments and simulation, the parameters in the Cowper-Symonds and Johnson-Cook high strain rate constitutive model were determined by using the inverse identification method. The flow stress of 5052-O aluminum alloy sheets was predicted at the high strain rate. By comparing the simulated and experimental results, it is confirmed that the Johnson-Cook hardening model is more accurate in describing the hardening behavior of the 5052-O aluminum alloy sheets. Finally, a validation experiment was conducted based on the determined parameters, and the deformation height, thickness, and strain at the marked points of the specimens in the simulation were compared with those in the experiments. The experimental data and the simulation results corroborate with each other, confirming the reliability.

To investigate the plastic deformation behaviors and martensitic transformation rules of 0.5 mm thick 304 stainless steels at room temperature, uniaxial tensile tests were conducted at five different strain rates of 0.000 67 s-1, 0.002 s-1, 0.01 s-1, 0.1 s-1 and 1.0 s-1, with subsequent X-ray diffraction(XRD) analysis for phase analysis. The results reveal a notable increase in yield strength with rising strain rate, indicating strain rate strengthening effects. Additionally, due to plastic work converting into heat during tensile processes, martensitic transformation was inhibited, resulting in a slight tensile strength reduction. Below a true strain of 0.27, work hardening rates decrease under varying strain rates. However, beyond this threshold true strain, significant secondary hardening occurs under low strain rates, which is attributed to the internal martensitic transformation.To address this phenomenon, the Olson-Cohen equation was integrated into the traditional Johnson-Cook model to characterize secondary hardening during tensile processes across different strain rates. The improved Johnson-Cook model achieves high accuracy in predicting rheological stress changes, with deviations of 3.23%, 3.42%, 4.13%, 4.09%, and 5.14% respectively compared to experimental values, effectively capturing the secondary hardening stage at various strain rates.

 The ultrafast solution with pulsed instantaneous currents and subsequent aging strengthening of aluminum alloys were proposed and the mechanics properties and microstructure evolution of aluminum alloys were analyzed by means of macro and micro experiments. The results show that the yield strength of 7075 aluminum alloys decreases gradually with the increase of discharge voltages, but the elongation of 7075 aluminum alloys shows a trend of “small increase-decrease-large increase”. When the peak pulse currents exceed 86 kA(corresponding to a discharge voltage of more than 9 kV), the mechanics tensile curve of the material appears the Portevine Le Chatelier(PLC) effects. When the peak pulse currents exceed 96 kA(corresponding discharge voltage exceeds 10 kV), the elongation of the samples increases by more than 508.09%. It is found that the dislocation density in the materials decreases at 10 kV voltage, η′ phase dissolves back into the aluminum matrix and forms susaturated solid solution, which significantly improves the plasticity of the materials. The results show that ultrafast(<1 ms) solution of 7075 aluminum alloys may be achieved by pulsed instantaneous currents. The strength of 7075 aluminum alloys reaches the peak after 21 hrs of artificial aging, and the hardness after peak aging reaches 98.69% of that of conventional solution quenching.

The coil design and forming processes of electromagnetic flanging of conical holes were achieved by establishing a finite element model using LS-DYNA finite element simulation software. A coil with variable turn spacing was designed, and the optimal discharge voltage was determined to investigate their influence on formability. Subsequently, a processing test was conducted to obtain parts meeting technical requirements. The results demonstrate that utilizing a coil with variable turn spacing design increases the electromagnetic force density in the small circle area, significantly enhances the forming height in this region, and improves overall forming uniformity. As voltage increases, there is an accompanying increase in electromagnetic force; consequently, there is rapid reduction in die gap within the small arc regions while remaining almost unchanged within large arc regions. Additionally, die gap within straight side regions rebounds after initial decrease. The optimum discharge voltage of 14 kV results in a maximum die gap of 0.61 mm and thinning rate of 18%, so that technical requirements are met.

In view of the formability problems caused by the strain rate effects in the high-speed stage deep drawing process of pure tantalum thin-wall members, the identification of the constitutive model was carried out, and the Johnson-Cook depth-forming model was constructed considering the strain rate effects of materials. The results show that the pure tantalum sheet shows an obvious strain rate reinforcement effect, and the yield strength under dynamic loading is much higher than that under the quasi-static stretch. The thermal coupling simulation and forming experiments of high speed stage deep drawing of tantalum capacitor shells were carried out. The results indicate that the simulation results of wall thickness distributions are relatively consistent with the experimental ones, and the wall thickness of the final pieces increases when the forming speed increases; the maximum thinning area of the final drawn parts occurs in the middle areas of the cylinder walls, where the highest temperature is positively correlated with the forming speed; the metallographic structures of the final shapes do not change significantly at different forming speeds, with only change the grain shape and size of different deformation areas.

When deep drawing sheets of varying thicknesses, different blank holder gaps were formed. In the traditional electrically controlled permanent magnet blank holding processes, the medium in the blank holder gaps was air, which created a magnetic circuit air gap during magnetic loading, leading to magnetic losses. A design for MRE was proposed as a magnetic medium to fill the blank holder gaps, creating an electrically controlled permanent magnet blank holding method without magnetic circuit air gaps, thereby reducing magnetic losses. A blank holding force loading structure with 36 magnetic pole units was designed, and finite element simulations were conducted under different blank holder gaps and varying magnetic loading levels to analyze the change in crimping forces with the addition of MREs on the blank holding force, followed by experimental validation. The results show that the addition of MREs may effectively enhance the blank holding forces with a more significant improvement as the blank holder gap increases, and the inclusion of MREs does not affect the distribution of the blank holding forces in the sheet blank holding areas. Deep drawing experiments were conducted using cylindrical parts as the experimental subjects, verifying that the new processing method is entirely feasible. 

 Aiming at the problems of ruptures due to low formability and dimensional deviations due to large rebound of complex thin-walled components of high-strength and lightweight materials during room temperature forming, 2024 aluminum alloy which was widely used in the aerospace field, was used as the object of the study, and the unidirectional tensile tests were carried out respectively at low and high strain rates to investigate the effects of strain rate on the plasticity of 2024 aluminum alloys. By comparing and analyzing the bending forming of sheet at different angles under traditional stamping, high-speed stamping and impact hydroforming, the study decoupled into the effects of high strain rate and liquid medium on sheet springback. The results suggest that under high strain rate loading, the 2024 aluminum alloys demonstrate a significant enhancement in formability, with a maximum elongation increase of up to 112.92%. Under the impact hydroforming mode, which combined the characteristics of high-strain-rate and liquid medium loading, the 2024 aluminum alloys exhibit a significant reduction in springback, with a maximum reduction in springback angle of up to 110.25%, even leading to a negative springback phenomenon. 

To explore a novel method of magnetic pulse expansion joining for dissimilar metal tubes with a magnetic field shaper structure, the distributions of electromagnetic forces were analyzed under the conditions of magnetic field shaper and the bulging behavior of aluminum tubes. The influences of main processing parameters on the magnetic pulse expansion joints were investigated through pull-out experiments. The results show that the magnetic field shaper significantly increases the value of electromagnetic forces applied to the bulging areas of the aluminum tubes. The overlapping length between the aluminum tube and the working zone of the magnetic field shaper has a significant impact on the bulging deformations of the aluminum tubes. When the overlapping length is 1.5 times the length of the working zone of the magnetic field shaper, the maximum effective contact area is obtained. Under the conditions of only elastic deformations of the outer tubes, the collision pressures are positively correlated with the discharge voltages, and the peak pull-out loads of the joints increase with the increase of discharge voltages. As the radial clearances between the tubes increase, the peak pull-out loads of the joints show a trend of increasing and then decreasing while the other processing parameters remaining the same. The maximum pull-out load of the joints reaches 5021 N under the condition of discharge voltage of 17 kV, radial gap of 4.0 mm, and overlap length of 15 mm.

With the objectives of low control complexity, no concomitant rotating features at the endpoint, and fewer degrees of freedom, the 2-(U+UPS)PU+UPU 3 DOF serial-parallel translational robotic leg was proposed. The leg mechanisms mobility was analyzed and the kinematics model of the leg mechanisms was established based on the screw theory. The workspace and the posture properties of the endpoints were obtained through simulation. The velocity Jacobian matrix and the force Jacobian matrix were deduced, and the change rule of velocity and statics properties was analyzed and obtained. A prototype sample of the proposed leg mechanisms was developed, the feasibility was verified. 

In order to effectively improve the quality of GaAs-based semiconductor laser cavity mirrors, a new type of scribing method was proposed and carried out in simulation analysis and processing experiments. A finite element simulation model of the scribing processes of GaAs materials was established to optimize the existing processing methods and to investigate the distribution of scribing loads and stresses under different processes. A cleavage processing validation experiment was carried out to analyze the morphological characteristics of the cleavage surfaces. It is found that the optimized processing method, which involves scribing from the inside out, can effectively reduce the degree of material surface damages in the scribing processes and reduce the brittle fracture phenomenon. The experimental results were in high consistency with the simulation ones.

A mixed multi pose motion synthesis method was proposed to achieve accurate take-and-place tasks of planetary gear mechanisms with different velocities. The unequal velocity planetary gear train was regarded as a combination of planar 2R open chain mechanism and non-circular gear transmission mechanism. Constrained by the key pose(exact and approximate) data on the ideal trajectory, a mixed multi-pose motion synthesis model of the planar 2R open chain was established based on the condition of constant link length, and the optimal structural parameters were obtained by homotopy algorithm. The calculation and distribution method of the non-circular gear ratio was given, and the mixed multi pose motion synthesis of unequal velocity planetary gear train was realized. The proposed method was applied to design the seedling picking mechanism in the field of agricultural machinery to meet the requirements of accurate taking and placing of vegetable pot seedlings. The correctness of the proposed method was verified by virtual simulation analysis and physical prototype experiments.

 In response to the issues of poor buffering, high energy consumption, and single driving mode in current rigid actuators, a multi-mode elastic actuator for legged robots was proposed. The actuator utilized a motor to drive a screw nut in series with a spring, combined with a braking device, to achieve multi-mode output. Firstly, the design of the elastic actuator was based on the motion requirements of the knee joint in legged robots. Subsequently, a coupled rigid-soft dynamics model of the multi-mode elastic actuator was established to investigate the effects of different elastic coefficients and load masses on the output performance of the actuators. Finally, a prototype of the multi-mode elastic actuator was developed, and a control system hardware and software platforms were set up. Performance tests of the actuators and experimental studies of the applications in mechanical legs were conducted. The experimental results show that the actuators may effectively switch between modes, and the outputs meet the motion requirements of the knee joints, validating the effectiveness of the multi-mode elastic actuators driving performance.

In order to explore the material removal mechanism and the effects of milling force and hole quality in the helical milling processes of SiCp/Al composites, the formation mechanism of the machined surface was studied by finite element simulation, and then the accuracy of the simulation was verified by experiments. The influences of process parameters on milling force, hole wall processing morphology and entrance and exit edge quality were explored. The results show that the milling force in the helical milling processes decreases with the increase of spindle speed, and increases with the increase of pitch and revolution speed. The uniformity of machined surface morphology increases with the increase of spindle speed, and decreases with the increase of pitch and revolution speed. The quality of the outlet edge increases with the increase of the spindle speed and the revolution speed, and decreases with the increase of the pitch. The inlet edge quality decreases with the increase of spindle speed and pitch, and the revolution speed has no effect on the inlet quality.

Predicting the temperature field of generating grinding for face gears was challenging due to two factors. One was the complex relative motions and contact variations between the grinding wheel and the face gear, which rendered the conventional gear grinding temperature field model ineffective. The other was that most of the existing grinding temperature studies adopted the contact zone between the grinding wheel and the workpiece as a moving banded heat source, neglecting the micro-cutting behavior of discrete abrasive grains in the grinding contact area, which led to low accuracy of the grinding temperature field computation. To address these issues, a material removal model of face gear was established, the expression of material removal parameters was derived, and a novel grinding temperature prediction method was proposed that took the discrete abrasive grains as the computational unit and integrated the heat flux modeling with the grinding force model of different grinding phases(sliding, ploughing and cutting). The grinding temperature measurement experiments of face gears demonstrate that the prediction errors of this method range from -6.94% to 9.29%. It is also observed that the temperature field exhibits distinct features of discreteness, local confinement and non-linear variation， and the mechanism of these features was discussed.

A coupled fluid-solid-particle aerodynamics model was developed to investigate the spatial and concentration distribution of tire wear particles emitted by heavy container trucks under varying velocities. The results indicate that the dispersion of tire wear particles from heavy truck tires is markedly affected by the trailing vortex. Laterally, the dispersion width behind the vehicle initially increases before stabilizing, with a maximum width of 3.0 meters observed. The particle concentration follows a similar trend, peaking at 0.34 mg/m3 at a lateral distance of 1.0 meter from the vehicle. Longitudinally, the height of particle dispersion rises initially and then levels off, with the highest point reaching approximately 4.8 meters at 4.0 meters behind the vehicle. The concentration pattern mirrors this, with a peak concentration of 0.33 mg/m3 at a height of 0.5 meters, located 1.0 meter behind the vehicle along the longitudinal axis. This research offers significant insights into the spatial characteristics and concentration patterns of tire wear particles, providing a scientific reference for addressing environmental concerns stemming from wear particle emissions by heavy container trucks and for devising effective mitigation strategies.

Based on the fatigue experimental data in the literature at 0.4%, 0.8% and 1.0% strain amplitude, the relationship among hardening parameters and strain amplitudes was systematically investigated, and the fitted curves of hardening parameters with respect to strain amplitude were obtained. A finite element model was established to reflect the fatigue cycle hysteresis curves, peak stress evolution curves and damage evolution curves. Through numerical simulation combined with the Manson-Coffin equation, fatigue life prediction was carried out at 0.5%, 0.7%, 0.9%, and 1.2% strain amplitudes respectively. Low cycle fatigue experiments were conducted on 316 stainless steels under strain amplitudes of 0.9% and 1.2%, and the life prediction results were verified. The results indicate that the predicted fatigue response processes are highly consistent with the experimental results， the life prediction error under 0.9% strain amplitude is as 21.1%, and the error under 1.2% strain amplitude is as 5.3%， which proves the accuracy of the fatigue response and life prediction improvement method. 

To address the limitations imposed by manufacturing processes on the large-scale applications of octahedral metamaterials, a discrete assembly design and performance control method for octahedral metamaterials was proposed. Firstly, the traditional three-dimensional octahedral metamaterial was disassembled into two-dimensional modular units, which were assembled into three-dimensional octahedral metamaterials and periodically extended structures using stable and easily disassembled bolt connections, and a parametric form of the discrete assembly design model was derived. Secondly, the mechanics characteristics of the modular unit structure were analyzed, and finite element analysis was employed to verify the mechanics performance of the discrete assembly model. Finally, based on digital coding and employing a third-order Rubiks Cube arrange cube array, a method for performance regulation was proposed to optimize the performance differences in the orthogonal directions of the discrete assembly octahedral metamaterials. The results demonstrate that the manufacturing and extension forms of octahedral metamaterials are enriched by the discrete assembly design facilitated by bolt connections. The performance deviation resulting from the discrete assembly design is effectively addressed by the third-order Rubiks Cube model of regulation, providing an innovative solution for achieving low-cost manufacturing and facilitating the large-scale applications of octahedral metamaterials.