Orientation Dependence of the Micro-Pillar Compression Strength in an Electron Beam Melted Ti–6Al–4V Alloy

An α/β two-phase Ti-6 Al-4 V alloy was fabricated by electron beam melting to obtain a basketweave structure.The orientation dependence of the mechanical properties of Ti-6 Al-4 V alloy was studied by micro-pillar compression and post-mortem transmission electron microscopy analysis.The results indicate that different grains have different mechanical responses,and the possible attributions were discussed.Besides the orientation effect,due to the limited volumes of micropillars,the size of the a phases,dispersion of the β phases,and the presence of the free dislocation path also affect the mechanical properties of the micropillars to a large extent.Although no direct link was discovered between the mechanical properties and the parent βorientations,this work provided a promising method to further study the anisotropic mechanical behavior in Ti-6 Al-4 V alloy.     

Mechanical behavior of electrochemically hydrogenated electron beam melting (EBM) and wrought Ti–6Al–4V using small punch test

The influence of electrochemical charging of hydrogen at j = ?5 mA/cm² for 6, 12, 48 and 96 h on the structural and the mechanical behavior of wrought and electron beam melting (EBM) Ti–6Al–4V alloys containing 6 wt% β and similar impurities level was investigated. The length of the α/β interphase boundaries in the EBM alloy was larger by 34% compared to that in the wrought alloy. The small punch test (SPT) technique was used to characterize the mechanical behavior of the non-hydrogenated and hydrogenated specimens. It was found that the maximum load and the displacement at maximum load of the wrought alloy remained nearly stable after 6 h of charging, showing a maximum decrease of ～32% and 11%, respectively. Similarly, hydrogenation of the EBM alloy resulted in a gradual degradation in mechanical properties with charging time, up to ～81% and 86% in pop-in load and displacement at the “pop-in” load, respectively. The mode of fracture of the wrought alloy changed from ductile to semi-brittle with mud-cracking in all hydrogenated specimens. In contrast, the mode of fracture of the EBM alloy changed from a mixed mode ductile-brittle fracture to brittle fracture with star-like morphology. The degraded mechanical properties of the EBM alloy are attributed to its α/β lamellar microstructure which acted as a short-circuit path and enhanced hydrogen diffusion into the bulk as well as δ_a and δ_b hydride formation on the surface. In contrast, a surface layer with higher concentration of δ_a and δ_b hydrides in the wrought alloy served as a barrier to hydrogen uptake into the bulk and increased the alloy resistivity to hydrogen embrittlement (HE). This study shows that EBM Ti–6Al–4V alloy is more susceptible to mechanical degradation due to HE than wrought Ti–6Al–4V alloy.     

特大悬索桥顺层山脊重力式锚碇基坑爆破开挖

爆破开挖山脊重力式锚碇基坑,势必扰动溶蚀严重顺层山体,易致岩体塌落和岩层滑动,影响后期锚碇稳定,特别是类似于赤水河特大桥情况,控制爆破扰动至关重要。针对特大桥特殊的地貌,复杂的地质构造,结合锚碇基坑开挖轮廓设计线,依据爆破地震波能流密度分布主方向及其大小特征等爆源因素相干性等控制爆破理论,对特大桥顺层山脊重力式锚碇基坑爆破开挖参数进行研究,提出了适宜的开挖工艺,经监测岩层损伤在控制范围内。     

Hydrogen annealing induced physical properties of ZnTe thin films

The ZnTe material has an unprecedented role in the fabrication of high efficiency CdTe thin film solar cells and optimization of hydrogen annealing induced physical properties of ZnTe films is next required step. Consequently, in the present work, the impact of Hydrogen annealing temperature on the structural, optical, electrical, topographical, morphological, and compositional properties of ZnTe films is explored. The ZnTe thin films (having 300 nm thickness) are grown via electron-beam evaporation technique on glass and ITO substrates followed by annealing at different temperatures under a Hydrogen atmosphere. The ZnTe films are found to crystallize in cubic phase with (111) predominant peak having crystallite size in the range of 19–28 nm, whereas annealed films demonstrated lower optical transmittance vis-à-vis to pristine films. The PL spectra exhibit two luminescence peaks with a stronger band at ～351 nm and a weaker band at ～450 nm. Ohmic behavior of ZnTe films is assured through I–V characteristics, while the AFM images revealed hill-like surface topographies. The FESEM image of pristine films demonstrated a homogeneous surface comprising spherical grains whereas annealed films have spherical, stone, and blisters like morphologies. The EDS patterns assured the Te element richness as well as successful ZnTe films deposition. The observed findings signify that the Hydrogen annealing at different temperatures notably modified the physical properties of ZnTe films.     

阴极铜剥片装置的优化改造

针对阴极剥片机组核心区域剥片装置故障高的问题 , 结合生产操作 , 以及实际检修过程 , 从设备的角度分析剥片装置故障率高的主要原因 , 根据原因提出设备改进方案 , 降低剥片装置故障率，保证剥片机组稳定运行，并且通过改进检修方式，减少故障检修时间，降低检修劳动强度。     

Failure load prediction and optimisation for adhesively bonded joints enabled by deep learning and fruit fly optimisation

Adhesively bonded joints have been extensively employed in the aeronautical and automotive industries to join thin-layer materials for developing lightweight components. To strengthen the structural integrity of joints, it is critical to estimate and improve joint failure loads effectually. To accomplish the aforementioned purpose, this paper presents a novel deep neural network (DNN) model-enabled approach, and a single lap joint (SLJ) design is used to support research development and validation. The approach is innovative in the following aspects: (i) the DNN model is reinforced with a transfer learning (TL) mechanism to realise an adaptive prediction on a new SLJ design, and the requirement to re-create new training samples and re-train the DNN model from scratch for the design can be alleviated; (ii) a fruit fly optimisation (FFO) algorithm featured with the parallel computing capability is incorporated into the approach to efficiently optimise joint parameters based on joint failure load predictions. Case studies were developed to validate the effectiveness of the approach. Experimental results demonstrate that, with this approach, the number of datasets and the computational time required to re-train the DNN model for a new SLJ design were significantly reduced by 92.00% and 99.57% respectively, and the joint failure load was substantially increased by 9.96%.     

Predicting shear strength of slender beams without reinforcement using hybrid gradient boosting trees and optimization algorithms

Shear failure of slender reinforced concrete beams without stirrups has surely been a complicated occurrence that has proven challenging to adequately understand. The primary purpose of this work is to develop machine learning models capable of reliably predicting the shear strength of non-shear-reinforced slender beams (SB). A database encompassing 1118 experimental findings from the relevant literature was compiled, containing eight distinct factors. Gradient Boosting (GB) technique was developed and evaluated in combination with three different optimization algorithms, namely Particle Swarm Optimization (PSO), Random Annealing Optimization (RA), and Simulated Annealing Optimization (SA). The findings suggested that GB-SA could deliver strong prediction results and effectively generalizes the connection between the input and output variables. Shap values and two-dimensional PDP analysis were then carried out. Engineers may use the findings in this work to define beam's geometrical components and material used to achieve the desired shear strength of SB without reinforcement.     

Calibration of laser beam direction for optical coordinate measuring system

For the purpose of measuring free form surfaces of some key parts in the aviation field accurately and effectively, such as blades, a non-contact optical coordinate measuring system is set up in the paper. A laser displacement sensor is mounted on the Z axis of a CMM via a turntable and adjusted to the suitable orientation according to the shape of the target surface. The combination of optical sensor and CMM can reach the full potential of them both. To enable the laser sensor to perform measurement in every direction, a calibration method used to determine the laser beam direction based on a standard sphere is proposed, the principle of which is analyzed in detail in the paper. In the calibration procedure, the sensor moves at an equal step along X, Y and Z axes respectively and then equation sets are established to calculate the unit direction vector of the line which the laser beam is on. In the process of solving the unknown quantities, a new parameter substitution method is applied. Finally, a gauging block and a sphere with known size are used to verify the method. As the experimental results show, the measuring errors in several directions are all smaller than 0.05 mm, which manifests that the calibration method proposed can meet the requirements of reverse engineering.     

新型提渣装置在步进式加热炉上的开发应用

针对步进式加热炉炉底出渣较困难的情况,分析氧化铁皮渣产生的原因,开发了一种新型提渣装置,以解决炉底地坑内堆积炉渣的清理问题,实现了无需用天车即可将炉底氧化铁皮渣运至地面以上。通过以上工作,承钢成功研制了一种步进式加热炉炉底提渣专利装置。     

土层锚杆在深基坑支护中的应用研究

针对土层锚杆在深基坑支护中的应用,提出一种适用于实际工程支护设计的数学方法。通过对土层锚杆支护理论及受力机理进行研究分析,结合锚杆支护在地铁深基坑工程中的应用实例,基于锚杆抗拔承载力试验及锚杆轴力的监测数据,采用统计归纳的数学分析方法,对几种设计理论与实测结果之间的关系进行分析,提出了采用粘结强度影响系数法对土层锚杆在深基坑支护工程中的应用进行设计的数学描述,给出了相应的数学表达式。