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Laser deposition manufacturing (LDM) technology provides the potential to manufacture large, difficult-to-process metal components for aerospace and other applications. However, the residual stresses resulting from the considerable temperature gradients in the LDM process can lead to distortion and even cracking of the fabricated components. Rapidly predicting the distortion for large additive metal components is critical to controlling the distortion and achieving high-quality forming of large components. Considering the principle of LDM technology, the partitioning method based on typical geometric features for aerospace titanium alloy frames, beams, and wall plates is proposed in this paper. It establishes a rapid prediction method for distortion of large additive metal components based on feature partitioning and temperature function method (TFM) by considering the effect of critical parameters of temperature function on distortion prediction. The results show that the prediction of additive component distortion through this method agrees with the results predicted by the traditional method and experimental results. Furthermore, the computational efficiency of the method has improved by 96% compared to the traditional approach, meeting the need for rapid distortion prediction in large metal additive components. [ABSTRACT FROM AUTHOR]

This paper presents an automatic fatigue crack propagation solution for particulate-reinforced composites. In this solution, the Eshelby's equivalent inclusion method is used to solve the elastic fields of a two-dimensional plane containing multiple elliptical inclusions. Then the continuous distributed dislocations in an infinite plane are adopted to model the multiple cracks in the plane containing multiple elliptical inclusions. By combining the two methods, a system of singular integral equations can be formulated based on the stress condition of the cracks. The stress intensity factor of each crack can be obtained by solving the singular integral equations. The propagation of the cracks is studied based on the maximum circumferential stress criterion. Numerical examples are presented to show the complicated changes in the stress intensity factors and crack growth behaviors of the cracks affected by the inclusions. [ABSTRACT FROM AUTHOR]

This paper presents a numerical solution to calculate the two-dimensional elastic fields of a finite plate containing a circular inclusion. The boundaries of the plate are modeled by distributed dislocations. This method results in a system of singular integral equations with Cauchy kernels which can be solved by Gauss-Chebyshev quadrature method. The elastic fields of the plate can be solved with the integral along the whole boundary which is modeled by distributed dislocations. Several numerical examples are given to assess the performance of the presented method. [ABSTRACT FROM AUTHOR]

The intermittent cutting behavior, performing as periodic contact phase and separation phase between abrasive grit and workpiece, is an important characteristic in the ultrasonic vibration-assisted grinding (UVAG). This study investigated the effect of intermittent cutting behavior on the grinding force in UVAG. At first, a grinding force model was established by determining the quantity of effective grits and the grinding force of a single grit. Then, the influences of ultrasonic vibration phase on the intermittent cutting behavior and grinding force were discussed. Finally, the prediction accuracy of the model was tested through experiments. Results indicated that the intermittent cutting behavior was divided into the contact phase and separation phase. A large unchanged chip thickness of 1.05 μm was generated at the start of contact phase. The quantity of effective grits firstly increased to maximum 232 at the vibration phase of 0.5 π and then gradually decreased to zero when entering the separation phase. The maximum error of the grinding force model was 15%, indicating that the model was of high accuracy for the force prediction in UVAG. [ABSTRACT FROM AUTHOR]

The ATP-gated P2X7 receptor is highly expressed in microglia and has been involved in diverse brain diseases. P2X7 effects were also described in neurons and astrocytes but its localisation and function in these cell types has been challenging to demonstrate in situ. BAC transgenic mouse lines have greatly advanced neuroscience research and two BAC-transgenic P2X7 reporter mouse models exist in which either a soluble EGFP (sEGFP) or an EGFP-tagged P2X7 receptor (P2X7-EGFP) is expressed under the control of a BAC-derived P2rx7 promoter. Here we evaluate both mouse models and find striking differences in both P2X expression levels and EGFP reporter expression patterns. Most remarkably, the sEGFP model overexpresses a P2X4 passenger gene and sEGFP shows clear neuronal localisation but appears to be absent in microglia. Preliminary functional analysis in a status epilepticus model suggests functional consequences of the observed P2X receptor overexpression. In summary, an aberrant EGFP reporter pattern and possible effects of P2X4 and/or P2X7 protein overexpression need to be considered when working with this model. We further discuss reasons for the observed differences and possible caveats in BAC transgenic approaches. [ABSTRACT FROM AUTHOR]