Analysis of different techniques for obtaining pre-cracked/notched small punch test specimens

Nowadays, there are standards for determining the mechanical and fracture properties of a material. However, these standards require a sufficient amount of material to be tested, something that is not always possible or convenient. In those cases where there is not enough material for conducting conventional tests to determine these properties of the material analyzed, there are now several non-standard tests that will achieve this purpose. One of them is the small punch test (SPT), which basically consists of deforming a miniature specimen using a high-strength punch, while the sides of the specimen are clamped between two dies. One of the greatest challenges at present is to obtain the fracture properties of a material from this type of test using pre-cracked specimens. To achieve this initial crack in the SPT specimen prior to fracture testing, there are two techniques which are mainly being used at present. The first one uses high-precision micromachining (HPM), while the second relies on laser-induced micromachining (LIM). The main objective of this paper is to analyze the differences between these two techniques, taking into account the shape of the pre-crack obtained and the stress distribution at the pre-crack tip during the test. In this way, it is possible to determine which of them is the most appropriate for estimating the fracture properties of the material used.     

EthernetPOWERLINK在机器控制领域中的应用

EthernetPOWERLINK技术是最早被开发和投入使用的一种实时通信技术，目前它已经被广泛地应用于各类对动态性能和精度要求较高的机器控制场合。本文主要介绍EthemetPOWERLINK技术在CNC与机器人和高速、高精度同步运动控制领域中的应用。     

液压控制在焦炉取门机构中的设计分析

研究了焦炉取门机构液压控制原理设计及性能特点,采用减压、比例、浮动、磁致伸缩等技术,使取门机构的精确性、稳定性、安全环保及节能更加显著。     

一种新型滑坡体无线远程监测系统设计

针对目前滑坡体监测仪器高测量精度、高可靠性、高自动化程度及低功耗的要求,设计了一套滑坡体全数字高精度自动远程监测系统。系统以STM32为核心,集成了SCA100T高精度双轴加速度传感器、MPS-S-400 mm-P位移传感器及SRY-1雨量计,采用SIM900模块实现GSM网络接入,基于12 V/40 AH蓄电池和小型太阳能发电系统完成系统持续供电。系统程序设计采用动态周期采集机制降低功耗,利用雨量阈值触发,驱动倾角传感器与位移传感器采集,并启动GSM实现远程数据传输。实验结果表明：系统能够实现滑坡体区域的雨量、表面位移和深部倾角参数自动化远程采集与传输;雨量采集精度为0.1 mm、地表位移采集精度为0.022 mm、深部倾角采集精度高达0.035°;该系统在无太阳能充电的环境下续航时间持续15 d,正常日照条件下持续工作时间大于90 d。     

高精度仪表自动判读技术研究

对高精度仪表自动判读方法进行了研究,研究过程主要分为三个部分。首先,根据视差形成原理分析了低精度仪表自动判读方法镜头的正确位置。接着,分析了采用低精度仪表自动判读方法对高精度仪表进行自动读数时,引入误差会增大高精度仪表的读数误差。最后,提出了一种采用图像处理技术及伺服跟踪技术相结合高精度模拟仪表读数自动识别的方法。实验结果表明,这种方法非常适宜于高精度仪表自动判读。     

智能称重仪表的原理与设计

运用单片机技术设计而成的智能称重仪表，具有结构简单、性能可靠、称重准确、功能齐全等特点，所采用的模拟输入接口电路仅用一个电阻就能对增益进行准确校正，大大优越于传统的三片运放电路。称重系统的硬件结构合理，软件设计先进，为计算机在电子衡器中的应用提供了良好的范例。     

近距离高精度汽车定点定位通信系统

针对汽车GPS通信系统在近距离定位上的精度问题,设计了一种近距离高精度定位辅助系统,并实现了周围汽车高效实时的通信。该系统利用超声波测距技术获得汽车之间的距离,并计算相对角度。通过有效的通信初始化算法与动态更新算法,将此数据与设备通信地址进行绑定,生成完整的节点信息。对节点信息进行处理,实时构建汽车周围环境的二维平面图,从而实现汽车近距离选择性通信的目的。     

Precision position control using combined piezo-VCM actuators

This paper presents the control performance of a high-precision positioning table using the hybrid actuators composed of the piezoelectric (PZT) actuators and voice-coil motors (VCMs). The combined piezo-VCM actuator features two main characteristics, i.e., a large operation range due to the long stroke of VCM, and a high precision and heavy load positioning ability due to the actuation of PZT impact force. In this paper, a one-degree-of-freedom (1-DOF) experimental setup was configured to examine the control performance and the parametric identification for the VCM was performed based on the recursive-least-square (RLS) method. The control performance was effectively demonstrated by using a switching controller configured by an integral variable structure controller (IVSC) for the VCM to conduct rough position control and an impact force controller (IFC) for the PZT actuator to conduct fine position control. The experimental results showed that the positioning table having mass 881 g was successfully positioned within the positioning accuracy of 10 nm by both the forward and backward positioning processes. In the forward control, it totally took 1.253 s for the sliding table to reach the target position of 450 μm; in the backward control, it took 1.387 s for the sliding table moving from the position of 450 μm to the target position of 200 μm.     

特厚煤层综放面高精度微震监测技术的应用

为了研究同煤集团塔山煤矿特厚煤层综放面围岩运动的规律、科学地进行开采设计并为矿山压力控制提供科学依据,根据综采放顶煤工作面的实际情况,按高精度微震监测技术的要求,确定了测区布置的原则,分析了影响监测定位精度的主要因素,对采集数据进行了研究比对,初步得出了塔山煤矿特厚煤层综放工作面围岩运动参数.     

高精度冷拔钢管模具的磨削工艺研究

介绍了用于冷拔高精密钢管的高光洁度模具的加工工艺试验情况。试验结果表明,改进磨创工艺,采用普通磨床可以生产高光洁度模具,这种模具可显著提高冷拔管的光洁度,降低模耗。