Ramp-Wave Compression Experiment with Direct Laser Illumination on ShenGuang-Ⅲ Prototype Laser Facility

Ramp-wave compression experiment to balance the high compression pressure generation in aluminum and x-ray blanking effect in transparent window is demonstrated with an imaging velocity interferometer system for any reflector(VISAR)on ShenGuang-Ⅲ prototype laser facility.The highest pressure is about 500 GPa after using the multilayer target design Al/Au/Al/LiF and ~10^(13)W/cm^2 laser pulse illuminated on the planar Al target,which generates the spatial uniformity to <1% over 500μm on the ablation layer.A 2-pm-thick Au layer is used to prevent the x-ray from preheating the planar ablation Al layer and window material LiF.The imaging VISAR system can be used to record the abrupt loss of the probe beam(λ= 532 nm)caused by absorption and reflection of 20-μm,30-μm and 40-μm-thick Al,i.e.,the blanking effect.Although there are slight shocks in the target,the peak pressure 500 GPa,which is the highest data up to now,is obtained with ramp-wave compression.

Structure design and compression experiment of the supporting node for JUNO PMMA detector

Introduction Jiangmen Underground Neutrino Observation is going to build a huge polymethyl methacrylate(PMMA)detector to hold 20,000 tons of liquid scintillator to capture neutrinos in a 700-m underground cave.This PMMA detector has a spherical shape with an inner diameter of 35.4 m and is supported by an outside stainless steel structure through 590 supporting nodes.The maximum compression force applied to these supporting nodes would be about 150 kN when the detector is running.Method This paper focuses on the design and validation of the PMMA supporting node and compares the effects of two gaskets(round gasket and ring gasket)on the supporting node stress and ultimate compression load.An innovative PMMA supporting node structure is first proposed,and a 1/4 symmetric model with the material nonlinearity and frictional contact boundary is established in the finite element analysis(FEA).Results The FEA results show that the principal stress of the structure is less than 3.5 MPa and the Mises stress is less than 5.5 MPa.The stress and deformation at the groove of the supporting node using the ring gasket are smaller than that using the round gasket.The compression experiments of the supporting node using two types of gaskets were conducted to study the effect of gaskets on the ultimate compression load of supporting node.The ultimate compression load of the supporting node with ring gasket is larger than 900 kN,which is six times of design load.In a comparison of experimental results with FEA,the maximum difference is 15.78%,demonstrating the validity of FEA results.Through the material test of PMMA and experiment of the PMMA supporting node,it is known that PMMA is a brittle material and it is very sensitive to sharp corner defects that should be avoided in the design of PMMA structure.

Prediction of Load-Displacement Curve of Flexible Pipe Carcass Under Radial Compression Based on Residual Neural Network

The carcass layer of flexible pipe comprises a large-angle spiral structure with a complex interlocked stainless steel cross-section profile, which is mainly used to resist radial load. With the complex structure of the carcass layer, an equivalent simplified model is used to study the mechanical properties of the carcass layer. However, the current equivalent carcass model only considers the elastic deformation, and this simplification leads to huge errors in the calculation results. In this study, radial compression experiments were carried out to make the carcasses to undergo plastic deformation. Subsequently, a residual neural network based on the experimental data was established to predict the load-displacement curves of carcasses with different inner diameter in plastic states under radial compression.The established neural network model’s high precision was verified by experimental data, and the influence of the number of input variables on the accuracy of the neural network was discussed. The conclusion shows that the residual neural network model established based on the experimental data of the small-diameter carcass layer can predict the load-displacement curve of the large-diameter carcass layer in the plastic stage. With the decrease of input data, the prediction accuracy of residual network model in plasticity stage will decrease.

考虑开发动态的定性经验出砂动态预测

储层出砂是一个动态发展的过程,仅凭开发初期的测井资料开展定性经验出砂静态预测难以满足开发需要,应综合考虑开发动态资料来开展出砂动态预测。首先,在模拟三轴应力环境下进行了不同含水饱和度及孔隙压力变化影响下的疏松砂岩纵波波速测试,研究表明随含水饱和度增加,纵波波速逐渐增加,且胶结越弱,含水饱和度对纵波波速影响越显著;随储层孔隙压力降低,纵波波速逐渐增加,且胶结越强,孔隙压力变化对纵波波速影响相对越小;其次,采用二元二次函数拟合及最优化原理建立了含水饱和度及无因次孔隙压力变化综合影响的纵波波速模型,在此基础上引入储层压力亏空、含水率及岩性影响因子,发展了经典的组合模量模型,建立了定性经验出砂动态预测模型。加蓬Obangue油田现场应用分析表明,该模型具有较好的可靠性和实用性。

Experimental Study on Friction in Ferrules during Compression Tuning of Fiber Bragg Grating

The effect of friction in ferules on compression tuning characteristics of fiber Bragg gratings (FBG) was observed and analyzed in this paper. It was demonstrated that the friction would make a non-uniform strain in the FBG and degradations of its reflection spectrum. To avoid the effect, some measures have been applied. Near 9 nm tuning range can be obtained with good spectral performance.

An interlaminar damage shell model for typical composite structures

Using the plate/shell elements in commercial software,accurate analysis of interlaminar initial damage in typical composite structures is still a challenging issue.To propose an accurate and efficient model for analysis of interlaminar initial damage,the following work is carried out:(A)A higher-order theory is firstly proposed by introducing the local Legendre polynomials,and then a novel shell element containing initial damage prediction is developed,which can directly predict transverse shear stresses without any postprocessing methods.Unknown variables at each node are independent of number of layers,so the proposed model is more efficient than the 3D-FEM.(B)Compression experiment is carried out to verify the capability of the proposed model.The results obtained from the proposed model are in good agreement with experimental data.(C)Several examples have been analyzed to further assess the capability of the proposed model by comparing to the 3D-FEM results.Moreover,accuracy and efficiency have been evaluated in different damage criterion by comparing with the selected models.The numerical results show that the proposed model can well predict the initial interlaminar damage as well as other damage.Finally,the model is implemented with UEL subroutine,so that the present approach can be readily utilized to analyze the initial damage in typical composite structures.

Damage evolution of PμLSE additive-manufactured micro-lattice metastructures: Synchrotron radiation 3D tomography image-based analysis

The manufacturing of additives with projection micro litho stereo exposure(PμLSE)has provided an opportunity for the fabrication of metastructures with complex microstructures at micro-nano resolutions.However,the performance evaluation of as-fabricated metastructures is challenging.The benefit of synchrotron radiation-based 3 D imaging techniques and advanced image processing methods makes it is feasible to study fabrication defects and damage processes of micro-nanoscale bodycentered cubic(BCC)lattices manufactured with PμLSE.First,synchrotron radiation technology is used to capture the structural features inside the micro-lattice samples.Subsequently,several types of statistical defects-based image finite element models are adopted to analyze the failure process of the structure under compression loading.Finally,comparisons between in situ experiments and numerical simulation results are performed for verification.The method of the combined non-destructive testing of synchrotron radiation and image finite element technology provides a robust technique for evaluating the performances of additive-manufactured micro-lattice with complex microstructures.