基于有限元的钢筋混凝土开口深梁设计与分析

深梁在受到外荷载时,其受力特点较为复杂。对此,采用有限元模型分析简支深梁和连续深梁存在孔洞时其受力变形规律。结论如下:①开口深梁在受到外荷载作用时,横截面不符合平面假定;②梁体受到外荷载时,其挠度值能够满足要求。③简支开口深梁梁体在开口处存在应力集中现象,应在梁两端增加斜向钢筋配置,在开口处也应加强钢筋构造,其余部位按照一般梁配筋。④两跨连续开口深梁开口处应力集中现象与单跨梁相比较弱,但中间支座受到的剪应力最大,需加强中间支座处的钢筋布置。

浅析一种深喉口液压冲孔机设计

这种深喉口液压冲孔机是为某工程机械企业生产需求,加工驾驶室、覆盖件等钣金件安装孔的设备。该机床以液压为动力,驱动液压缸上下移动,带动冲头移动,完成钣金件的冲裁加工,本机床具有体积小、造价低、结构简单紧凑、运行平稳、操作简单等特点,适用于小批量、多品质、大尺寸的钣金件工艺孔加工。

地下连续墙超深空口处理施工技术

结合工程项目的特点及常规空口处理技术中的不足,提出新颖的刚性接头墙体超深空口处理施工技术与柔性接头墙体超深空口处理施工技术,通过具体的施工及工程实践,证明上述两项施工技术具有节约成本,加快进度,减少环境污染,节约社会物质资源等优点,改变了常规空口处理的施工技术,在遇到类似工程项目时,可供借鉴与推广应用的施工技术。

硬质合金在中小型拉深、缩口模上的应用

本文阐述了用硬质合金制作中小型拉深、缩口模具有精度高、耐腐耐用等特点，在批量生产中可取得理想的经济效果。

地下连续墙超深空口处理施工技术浅析

介绍了地下连续墙空口处理的必要性,论述了地下连续墙超深空口处理施工工艺与方法,阐述了主要施工质量控制措施和实施效果。

敞口深腔铝件的加工工艺分析

本研究通过深入研究敞口深腔铝件加工工艺,分析出在铝件加工过程中存在断刀、粘刀以及小倒角这些问题,从这些问题出发,结合敞口深腔铝件加工的特点,提出解决上述问题的建议与意见,重点阐述了敞口深腔铝件的加工工艺流程,以期优化高速加工的工艺参数。

珠三角鼎湖—高明—金湾深地震测深剖面地壳构造与速度结构特征分析

为研究珠江三角洲及近海区域深部地壳结构,广东省地震局联合多家单位于2015年在珠江口区域实施了大规模三维人工地震测深实验.本文利用珠江口西侧NW向鼎湖—高明—金湾L1测线数据进行处理、解释,采用地震射线走时正演构建了该剖面二维速度模型.结果表明:沿剖面莫霍面深度从NW向SE,从30.0 km逐渐抬升到28.0 km,鼎湖至高明间存在莫霍面隆起;中地壳低速层非均匀连续,NW一侧速度低于SE一侧,且莫霍面隆起区之上为最显著的低速异常区域,中心最低速度为6.05 km·s-1;吴川—四会断裂、广州—恩平断裂可能为深部物质上涌的主要通道之一,两条断裂所围限的从珠江口西侧的鼎湖、高明往北东延伸到珠江口东侧的清远、从化区域为可能的连续莫霍面隆起区.

旋耕机防尘罩冲压工艺与模具设计深析

为了保证旋耕机防尘罩冲压件的顺利成形,并降低模具成本及模具数量和减少对冲压设备的使用,通过冲压工艺分析,确定冲压工艺方案,设计了落料拉深扩口冲孔复合模和冲6-013孔模两副模具来实现成形。所设计的两副模具既减少了模具数量和对冲压设备的使用,又降低了模具成本、提高了冲压生产的效率,保证了产品精度要求。截至目前,已经冲压生产2万余件,模具运行情况良好,所得冲压件质量稳定。

60m超深地下连续墙施工技术

分析了上海大中里地块60 m超深地下连续墙施工的难点,结合类似工程的成功经验,并根据试成槽和锁口管试拔的情况,最终确定了成槽设备,并对钢筋笼的形式进行了改进。通过采取一系列的技术措施后,较好地解决了超深地下连续墙塌方、混凝土绕流、垂直度、锁口管顶拔等施工难题。

Study on Remote Sensing of Water Depths Based on BP Artificial Neural Network

A momentum BP neural network model （MBPNNM） was constructed to retrieve the water depth information for the South Channel of the Yangtze River Estuary using the relationship between the reflectance derived from Landsat 7 satellite data and the water depth information. Results showed that MBPNNM, which exhibited a strong capability of nonlinear mapping, allowed the water depth information in the study area to be retrieved at a relatively high level of accuracy. Affected by the sediment concentration of water in the estuary, MBPNNM enabled the retrieval of water depth of less than 5 meters accurately. However, the accuracy was not ideal for the water depths of more than 10 meters.

大孔径工件内径测量装置设计

在诸多生产领域中常会涉及很多大孔径工件,为确保这些部件的内径尺寸符合工作和生产的需要,需要对这些内径尺寸进行测量。目前常用的测量工具并不能与这些部件的测量部位进行很好的抵压,同时由于工件的口径深浅不一,导致测量存在较大的误差。本文采用光栅尺作为测量元件,设计了两种内径测量装置,能够分别对深口和浅口的大孔径工件的内径尺寸进行有效的测量。本文设计的大孔径内径测量装置具有高效、准确、便捷的特点,能够为生产过程中工件的尺寸测量提供支持,保证工件的安装质量,提高生产的效率。

Process window diagram of conical cups in hydrodynamic deep drawing assisted by radial pressure

Major defects in forming of conical cups are wrinkles and rupture.Hydrodynamic deep drawing assisted by radial pressure（HDDRP） is a sheet hydroforming process for production of shell cups in one step.In this work,process window diagrams（PWDs） for Al1050-O,pure copper and DIN 1623 St14 steel are obtained for HDDRP process.The PWD is determined to provide a quick assessment of part producibility for sheet hydroforming process.Finite element method is used for this purpose considering the process parameters including pressure path,and the blank material and its thickness.Numerical results are validated by experiments.It is shown that the sheets with less initial thickness and higher strength show better formability and uniformity of thickness distribution on final product.The results demonstrate that the obtained PWD can predict appropriate forming area and probability of rupture or wrinkling occurrence under different pressure loading paths.

Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum

When an extremely thick rock bed exists above a protected coal seam in the bending zone given the condition of a mining protective seam, this extremely thick rock bed controls the movement of the entire overlying stratum. This extremely thick rock bed, called a ＂main key stratum＂, will not subside nor break for a long time, causing lower fractures and bed separations not to close and gas can migrate to the bed separation areas along the fractures. These bed separations become gas enrichment areas. By analyzing the rule of fracture evolution and gas migration under the main key stratum after the deep protective coal seam has been mined, we propose a new gas drainage method which uses bore holes, drilled through rock and coal seams at great depths for draining pressure relief gas. In this method, the bores are located at a high level suction roadway （we can also drill them in the drilling field located high in an air gateway）. Given the practice in the Haizi mine, the gas drainage rate can reach 73% in the middie coal group, with a gas drainage radius over 100 m.

Prediction of fracture limits of Ni-Cr based alloy under warm forming condition using ductile damage models and numerical method

The stretch forming and the deep-drawing processes were carried out at 300 and 673 K to determine the safe forming and fracture limits of IN625 alloy.The experimentally obtained strain-based fracture forming limit diagram(FFLD)was transformed into a stress-based(σ-FFLD)and effective plastic strain(EPS)vs triaxiality(η)plot to remove the excess dependency of fracture limits over the strains.For the prediction of fracture limits,seven different damage models were calibrated.The Oh model displayed the best ability to predict the fracture locus with the least absolute error.Though the experimentally obtained fracture limits have only been used for the numerical analysis,none of the considered damage models predicted the fracture strains over the entire considered range of stress triaxiality(0.33<η<0.66).The deep drawing process window helped to determine wrinkling,safe and fracture zones while drawing the cylindrical cups under different temperature and lubricating conditions.Further,the highest drawing ratio of 2 was achieved at 673 K under the lubricating condition.All the numerically predicted results of both stretch forming and deep drawing processes using the Hill 1948 anisotropic yielding function were found to be good within the acceptable range of error.

Wellhead anti-frost technology using deep mine geothermal energy

The auxiliary shaft is an important location for coal mine heating in the winter, where the main purpose of heating is to prevent icing of the shaft. Wellhead heating requires characteristics of openness, no-noise and big heat loads. The original coal-fired boiler heating mode causes significant waste of energy and environmental pollution due to the low efficiency of the heat exchange. Therefore, to solve these prob- lems, we will use deep mine geothermal energy to heat the wellhead by making full use of its negative pressure field and design a low-temperature water and fan-free heating system. Through numerical cal- culations we will simulate temperature fields, pressure fields and velocity fields under different air sup- ply temperatures, as well as different air supply outlet locations and varying number of radiators in the wellhead room of a new auxiliary shaft to find the proper layout and number of radiators that meet well- head anti-frost requirements from our simulation results, in order to provide guidelines for a practical engineering design. Tests on the Zhangshuanglou auxiliary shaft wellhead shows good, look promising and appear to resolve successfully the problem of high energy consumption and high pollution of well- head heating by a coal-fired boiler.

CAN-based Control System Design on Minor-caliber Deep Well Rescue Robot

By introdming a small-caliber deep well rescue robot, a hold-hug pattern rescue mechanism was brought forward. In order to reduce the volmne, the trader-well rescue imclmnism is modularizing designed. At the same tirae, the audio and video systyems, the illumination system and the ventilation system are expatiated. The rescuing robot can rescue the falling person in the deep well, it can save much manateral resources and time. It＇s really an ideal rescue device for the small-caliber fall.

Parametric Instability Analysis of Deepwater Top-Tensioned Risers Considering Variable Tension Along the Length

Parametric instability of a riser is caused by fluctuation of its tension in time due to the heave motion of floating platform. Many studies have tackled the problem of parametric instability of a riser with constant tension. However, tension in the riser actually varies linearly from the top to the bottom due to the effect of gravity. This paper presents the parametric instability analysis of deepwater top-tensioned risers(TTR) considering the linearly varying tension along the length. Firstly, the governing equation of transverse motion of TTR under parametric excitation is established. This equation is reduced to a system of ordinary differential equations by using the Galerkin method. Then the parametric instability of TTR for three calculation models are investigated by applying the Floquet theory. The results show that the natural frequencies of TTR with variable tension are evidently reduced, the parametric instability zones are significantly increased and the maximum allowable amplitude of platform heave is much smaller under the same damping; The nodes and antinodes of mode shape are no longer uniformly distributed along the axial direction and the amplitude also changes with depth, which leads to coupling between the modes. The combination resonance phenomenon occurs as a result of mode coupling, which causes more serious damage.

Physical and Numerical Modelling Applied to a Major New Port Development and Impacts of Its Deep Navigational Channel

This paper describes the use of a numerical and physical modelling study in the design of large breakwaters for a new port and dry dock complex on the southern coast of Oman. The numerical modelling was carried out to optimise the entrance channel layout with respect to wave penetration into the port and to refine design conditions for the sizing of the primary armour on the breakwaters. Wave conditions inside and outside of the port have been assessed using the 2-dimensional numerical wave penetration model MIKE21 EMS （Elliptic Mild-Slope）. As part of the design process, 3D physical modelling studies were also undertaken at Delft Hydraulics in the Netherlands to confirm the stability of the armour on the trunk and roundhead of the breakwaters and to verify the influence of the deep approach channel on stability. The opportunity was taken to extend the physical model tests to assess the influence of the deep channel on wave penetration through the port entrance. The paper focuses on the influence of the deep channel on wave conditions in the entrance to the port and compares the results from the numerical and physical modelling.

铝合金板材轮毂卷边轮缘成形工艺

为了提高铝合金板材轮毂的强度、刚度和外观质量,需对其轮缘进行卷边成形。轮缘部位的成形工艺因其高精度要求而变得复杂,且成形过程难于控制。通过试验研究和有限元模拟方法,对铝合金板材轮缘卷边部位的拉深-缩口成形工艺进行研究。建立了3-D弹塑性有限元模型,并给出合适的边界条件。分析了卷边轮缘成形过程中塌边、塌角和端面圆跳超差产生的原因。结果表明,通过一次拉深和30°、60°、90°的3次缩口成形,可以得到优良的卷边轮缘。