Search

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Here, the Response Surface Method （ RSM） is used to optimize the structure of a new Axial-Flux Permanent Magnet Memory Motor （AFPMMM） proposed in this paper. Main influencing parameters of the motor are preliminarily determined based on analysis of the electromagnetic performance equation and Orthogonal Experiment （OE), among which, three factors including soft magnetic ratio, number of rotor poles and air gap length, are selected as the design factors of OE. Then Electromotive Force （EMF), Total Harmonic Distortion （THD） and cogging torque are determined as the optimization factors, and the RSM is used as the optimization method. The Response Surface （RS） experiment is established by using the finite element software An soft Maxwell and the RS design software Design Expert. The simulation parameters and fitting curves of the motor under the combination model of different design factors are obtained. Different optimization methods are combined to meet the specific design requirements in this paper. Theoretical analysis and experimental results verify the feasibility and effectiveness of the proposed motor and optimization method. Then the optimization scheme is obtained through comparative analysis of the test data. The results show that the optimized motor not only reduces the cost of permanent magnet material, but also ensures good EMF and small axial force fluctuation. [ABSTRACT FROM AUTHOR]

This paper presents a finite-element approach to simulate the buckling process of the composite laminated plate containing a buried delamination. The delaminated composite laminates are analyzed using solid elements. In order to prevent the mutual penetration between the two parts above and below the delamination and to ensure coordinated deformation, a normal behavior of hard contact is applied at the interfaces of the delamination to take into consideration of the nonlinear contact effect between the debonded regions. Parametric analyses are conducted to investigate the effects of delamination depth, delamination length and aspect ratio on the buckling loads. Furthermore, buckling of a perfect laminate with the same geometrical parameters is simulated to obtain the critical buckling load. A comparison between the finite element prediction and the classic theoretical solution for the perfect laminate is carried out. It is found that they are in good agreement. The established model can simulate the buckling process of the composite laminated plate accurately.

The sensitivity and reliability of packaged high-g MEMS accelerometer strongly depends on die attach quality that should pay special attention in the operation. A package method based on die attach is presented for a prepared MEMS high-g accelerometers by using two die attach adhesives with different elasticity modulus. The effect of the die adhesive on the performances has been studied by using finite element analysis（ FEA） and Hopkinson pressure bar measurement system simultaneously. With the consistent package process,we have experimentally demonstrated that the characteristic of dynamic sensitivity for the prepared MEMS high-g accelerometers increases with the increasing of elasticity modulus of the die attach adhesives. From this result,it is possible to fabricate MEMS high-g accelerometer with bigger sensitivity by applying die attach adhesive with bigger elasticity modulus.

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A flexure hinge positioning stage with giant magnetostrictive actuator（ GMA） as the driving unit is designed,which is composed of multi- group flexure hinges and guided by elastic deformation under force. The theories of the energy equation,equation of deflection curve,axioms of statics and energy conservation equation are applied to establish the mathematic theory model of flexure hinge positioning stage. The driving force and output displacement of the flexure hinge positioning stage are analyzed on the basis of working requirements driven by GMA. The geometric parameters of radius R and minimum thickness t of flexure hinge are optimized to achieve the optimized structure parameters of the flexure hinge positioning stage. Finally,the flexure hinge positioning stage is simulated by finite element analysis and the simulation values and theoretical analysis values are compared,the accuracy of theoretical analysis is verified.

Exhaust manifold is a main heated component of engine,which has poor working conditions. High levels of thermal load can lead to deformation even cracking,which affect its normal working and reliability and durability. Aiming at the high thermal load of a high pressure common rail diesel engine,different fluid-solid coupling models was built and the temperature distribution and thermal stress of the engine exhaust manifold was stimulated and the influence of different structural factors on the exhaust manifold thermal load was calculated and analyzed. Results show that: the maximum temperature of the exhaust manifold changed from 805. 2 ℃ to 820. 8 ℃ as the outlet length increased,the maximum temperature of the exhaust manifold changed from 805. 2 ℃ to 819. 4 ℃ as the outlet diameter increasing,and the maximum temperature of the exhaust manifold dropped to 784. 0 ℃ as the outlet transferred to the body symmetry position. Structure factors such as exhaust outlet position,outlet length and outlet diameter had a great influence on the exhaust manifold thermal load. The maximum thermal stress value was 326. 21 MPa of the case of 21 mm outlet length and 5 mm outlet diameter outlet with the non-symmetry outlet position; the minimum thermal stress value was 174. 1 MPa of the case of 19 mm outlet length and 5mm outlet diameter with the non-symmetry outlet position.

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carbon fiber reinforced plastic (CFRP) laminated composites, called bi-stable composites, are applied as soft morphing host structural component. These bi-stable composites have two cylindrical stable states which have parallel direction between fiber direction of composites and principle curvature of bi-stable shape. Their final curvature can be tailored by the initial curvature. However, the cross-ply composites have twisted shape in a certain negative initial curvature. These twisted shapes also have bi-stability. Herein, the reasons for the twisted shapes are discussed from a mechanical perspective. In addition, the twisted shape was simulated by a developed analytical model considering the discussed mechanical mechanism. The simulation results show that the CFRP laminated composites have two kinds of bi-stable states (conventional shape or twisted shape) and a mono-stable state with respect to the negative initial curvature. These analytical results were verified by comparing them with those obtained by finite element analysis (FEA). [ABSTRACT FROM AUTHOR]

Permanent magnet motor offers various advantages such as simple construction and high efficiency which are highly demand in domestic appliances. The standard single-phase ceiling fan motors that are driven by the induction motor are inherently low efficiency. This paper presents an analysis on radial and Halbach permanent magnet array configurations of permanent magnet synchronous machine for ceiling fan. The proposed design of ceiling fan machine comprises a motor and a generator in one machine that implement a concept of the single rotor double stator. An analysis was conducted via finite element analysis to compare the performance of the flux distribution, air-gap flux density and back EMF between the conventional radial and Halbach permanent magnet machine. Overall, Halbach permanent magnet machine generates a high intensity of flux lines and flux density due to the self-magnetization features. However, the generated back EMF is not significant as compared to radial permanent magnet machines. Considering the simplicity of the design, radial array machine is identified as the optimized design configurations. [ABSTRACT FROM AUTHOR]

A modified viscoelastic constitutive model is proposed to predict cure-induced residual stresses in polymer matrix composites. The modifications rely on using the inverse of the Deborah number to describe regimes corresponding to a fully relaxed state, a viscoelastic state and an elastic state. The composite is only in a viscoelastic state for limited ranges of the Deborah number. By considering the evolution of the Deborah number during curing of the AS4/3501-6 composite, the composite is in a fully relaxed state when it is cured at high temperature and the degree of cure is lower than 0.73, and no further changes in the viscoelastic characteristics when the degree of cure is higher than 0.8. A 3D simulation of a composite laminate plate is used to predict the evolution of the residual stresses. The analysis reveals that the accurate simulation on the cure-induced residual stress should include the last two states of the entire cure process, and consider the stress relaxation, thermal deformation and chemical shrinkage. [ABSTRACT FROM AUTHOR]

Aiming at understanding the performance of the large telescope, those three basic methods to specify the wind load are shown while the response of the large telescope under wind was more and more interested by the engineers. The shortage and advantage of the three approach，namely，power spectral density method，computational fluid dynamics and modal model method were presented in the paper. Con­cretely， power spectral density method is the first method. According to this method，the wind spectrum cannot always satisfy the ideal model achieved form the statistics method. The computational fluid dynamics ( CFD) is the second one for this method，major concerned thing is the modeling accuracy. The results indicate that for the next generation ground based telescope，the previous testing on the dummy mirror is necessary to processed to achieve the response to the wind load，after the PSD and CFD is applied. [ABSTRACT FROM AUTHOR]

Objective: To investigate the biomechanical effects of en-mass retraction with different kinds of vertical traction on maxillary teeth. Methods: A three dimensional finite element model of en-mass maxillary anterior teeth retraction force system was constructed with CT scanning and MIMICS software, the initial displacement of maxillary teeth was calculated when adding vertical traction between anterior teeth. Results: Lingual tipping of anterior teeth decreased with vertical traction; The different locations of vertical force cause different effects on anterior teeth; The first molar seems to move in a way of distal tipping. Conclusions: Torque of anterior teeth could be easily controlled when adding vertical traction; Bodily movement seems more likely to occur with vertical traction; Vertical control was realized in en-mass retraction with micro-implant anchorage. [ABSTRACT FROM AUTHOR]

Aiming at the magnetic field analysis and iron loss calculation of switched reluctance motor (SRM, which has doubly salient structure, the method of iron loss calculation of SRM was investigated, and the relationship between the motor iron loss and quadrature components of core flux density was established. According to the core loss orthogonal equivalent theory, a method, Ellipse method, was presented to estimate the iron loss of SRM. A three-phase 12/8 SRM was analyzed with Ansoft so that the magnetic flux density and components Br,Bt could be got and their FFT could be achieved. The accuracy of the Ellipse method was evaluated on the comparison between the iron loss value using Ellipse method, and the iron loss value using Harmonic method. The results indicate that Ellipse method to calculate the iron loss is more accurate than the Harmonic method and more advantageous for the design of motor body,cooling systems and insulation materials of SRM. [ABSTRACT FROM AUTHOR]

new method of switched reluctance wind power generation position sensorless based on DFNN by FEA was proposed. Through current and magnetic linkage to get the angle of SRG rotor position, the nonlinear mapping of current-magnetic linkage-angle was built. By training these sample data from FEA, the angle of SRG rotor position was replaced by the output of DFNN to achieve SRG position sensorless. Simulation results show that the error between actual rotor position and estimate rotor position is small; SRG can commutate with great accuracy; and the output voltage of SRG wind power system under variable wind speed is essentially constant. [ABSTRACT FROM AUTHOR]

Through virtual design and virtual test, dynamic characteristics of safety and arming device with transient and high acceleration are studied. Based on the test result of acceleration in bore and the FEA method, a FEA model is built up and ballistm environment is input. Simulation result indicated that the intention of safety in arming device is deficient. With the clock mechanism movement in bore, the failure of safety and arming device is investigated. The result indicates that the transient and high acceleration hear the bore, acting on the radial direction of the munition is the main reason that causes the failure of safety and arming device. [ABSTRACT FROM AUTHOR]

In this work, the synergistic effect of 3D orthogonal woven structure and asymmetric carbon/glass hybridization on impact response was studied by experimental and numerical methods. The hybrid 3D orthogonal woven (H3DOW) composite plates were manufactured on a home-made 3D weaving machine. Impacts with various energies 42.9, 54.9, 66.9 and 78.9 J were applied to carbon (CG) and glass (GC) sides. The impact response was examined using fracture morphology observation and mechanical curves. Yarn-level finite element models including failure criteria and progressive damage law were established in ABAQUS/Explicit to compare the structural deformation and damage behavior. The impact side significantly influences the failure modes of H3DOW materials. GC specimen failed through delamination between carbon layers at non-impact side and subsequent fiber tensile breakage, whereas the crushing damage in the carbon yarn located in the impact-side and large area debonding between yarn and matrix resin in superficial layers was the dominant failure mode in CG specimen. This caused the CG configuration to exhibit better impact resistance with respect to the perforation threshold energy. [ABSTRACT FROM AUTHOR]