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Due to the mismatch of thermal expansion coefficients and effective moduli between fibers and matrix materials, local stress concentrations arise in composites during the curing process from the high preparation temperature to room temperature. To evaluate the effect of thermal residual stresses on local stress distributions in composites, a high-precision microscale model is established in this paper. The numerical results obtained indicate that the thermal residual stresses cannot give rise to plastic strains in the matrix. [ABSTRACT FROM AUTHOR]

Chang'e-5 (CE-5) mission is expected to land and sample in the Rümker region, north of the Oceanus Procellarum. To select optimal sampling points, the microwave radiation features in this mare unit are analyzed, and the dielectric constant and thickness of lunar regolith are retrieved based on Chang'e lunar microwave sounder (CELMS) data. According to the microwave brightness temperature (TB) maps, TB varying with frequency at noon and midnight are different, in which noon TB increases with frequency, but midnight TB does not follow this rule. Moreover, there are differences among TB distributions at the three higher frequencies, especially in the southern part. In addition, a great TB difference between noon and midnight can be seen in Rümker E that shows higher daytime temperature but lower nighttime temperature The inversion results reveal that the dielectric constant is lower in the west and north, higher in the middle and east, and the largest value occurs in Rümker E. As for the regolith thickness, most areas are uniform and no more than 4 m, with the thickest and thinnest regolith appearing in the northwest and Rümker E, no less than 6 m and about 2.5 m, respectively. Considering the safety and operability of landing and sampling, the northwest with thick regolith is recommended, while the Rümker E should be eluded. [ABSTRACT FROM AUTHOR]

Iron-based soft magnetic composites insulated with parylene C film were prepared via chemical vapor deposition polymerization, and their morphologies, magnetic properties, and corrosive resistance were investigated. Scanning electron microscopy and Fourier transform infrared spectrum confirmed that the surface of the iron particle was completely uniform insulated with parylene C, resulting in reducing the core loss of the synthetic compacts. The results show that compressed pressure has an important influence on the magnetic properties of the soft magnetic composites, enhance the magnetic induction value from 0.64 to 1.01 T and is obtained with increased the compressed pressure from 300 to 650 MPa. The loss separation results show that the hysteresis loss coefficient of 4 wt% parylene C insulated samples decreased from 1.743 to 1.657 and eddy current loss coefficient decreased from 0.019 to 0.012 as compared with uncoated compacts under the same compress pressure. The acid and salt corrosion resistance of the iron particles is apparently enhanced when the chemically stable parylene C layer was exited in the surface. [ABSTRACT FROM AUTHOR]

Iron-based soft magnetic composites with silicone resin coating have been designed to reduce the core loss and improve the magnetic properties of cores. The silicone resin serving as electrical insulating layer was modified by 3-glycidoxypropyltrimethoxy silane, and the effect of silicone resin content, coupling agent, annealing treatment, and thermal cycling on the magnetic properties of composites was investigated in the frequency range from DC to 150 kHz. The coated silicone resin insulating layer was characterized by scanning electron microscopy and energy dispersive spectroscopy. The results showed that the optimum coating content of silicone resin to attain the acceptable permeability and the minimum magnetic loss for the prepared composites is 4 wt%. The sample with silicone resin coat exhibited better DC-bias superposition characteristics compared to the uncoated sample, 6 wt% silicone resin coating sample have excellent percentage effective permeability (84.8%) under 50 Oe applied field. AC magnetic properties evaluated at 1 and 100 kHz do not vary with a 95% confidence interval with the number of thermal cycles; therefore, the properties of the silicone resin-insulating composites are stable under thermal cycling. [ABSTRACT FROM AUTHOR]

The paper applies dual BIE with crack opening displacements for the calculation of stress intensity factors of a 3D crack. A general transformation is introduced to remove the weak singularity no matter where the source point is located. A singular integration element is subdivided into several quadrilaterals and triangles with fine shapes to ensure the high accuracy of singular integrals. Two types of special crack front elements based on the quadrilateral discontinuous element are proposed to model the distribution of displacements in the vicinity of the crack tips. Results of our method are in very good agreement with the existing results. [ABSTRACT FROM AUTHOR]

As a widely used numerical method, boundary element method (BEM) is efficient for computer aided engineering (CAE). However, boundary integrals with near singularity need to be calculated accurately and efficiently to implement BEM for CAE analysis on thin bodies successfully. In this paper, the distance in the denominator of the fundamental solution is first designed as an equivalent form using approximate expansion and the original sinh method can be revised into a new form considering the minimum distance and the approximate expansion. Second, the acquisition of the projection point by Newton-Raphson method is introduced. We acquire the nearest point between the source point and element edge by solving a cubic equation if the location of the projection point is outside the element, where boundary integrals with near singularity appear. Finally, the subtriangles of the local coordinate space are mapped into the integration space and the sinh method is applied in the integration space. The revised sinh method can be directly performed in the integration element. Averification test of our method is proposed. Results demonstrate that our method is effective for regularizing the boundary integrals with near singularity. [ABSTRACT FROM AUTHOR]