摘要
为解决变温变湿状态下木材拉伸和压缩蠕变试验过程中普遍存在的试验环境难以控制、蠕变变形量难以测量、数据采集烦琐、设备长期运行稳定性较差等问题,依据木材拉伸及压缩力学性能的测试基本原理和相关国内外标准研制了一套木材拉伸及压缩一体化蠕变自动监测系统。系统主要由软件系统和硬件系统两个部分组成,软件系统基于VB语言和查表算法进行开发,硬件系统包括蠕变测试环境系统、框架和受力导向系统、加载系统、拉伸和压缩蠕变测试的转换系统、试件夹装系统及数据采集系统、检测装置与环境系统的连接机架、信号接收和转换系统。该套系统的试验环境参数可调控范围为温度-10~70℃,相对湿度10%~98%,风速为0.3~5.6 m/s,蠕变变形量测试精度为0.001 mm,数据采集间隔1 s~24 h多梯度可调。经过前期14.6 d的木材拉伸蠕变测试和30 d的木材压缩蠕变试验检验,证明该系统可对木材的拉伸或压缩蠕变变形量进行长时间、稳定可靠和高精度的实时动态监测、记录和显示。同时,本次研究的拉压转化装置和加载装置大大降低了同类系统的总质量及试验操作的复杂性,为木材拉伸及压缩蠕变测试和研究提供了一个新的平台。
In order to solve the problems of difficult to control experimental environment,difficult to measure creep deformation,cumbersome data acquisition and poor stability of long-term operation of the equipment in the process of wood tensile and compressive creep experiments under variable temperature and humidity,this research developed an integrated creep automatic monitoring system for wood tension and compression properties based on the basic principles of wood mechanical testing and relevant Chinese and international standards.The system consisted of eight parts:creep test environment system,frame and force guiding system,loading system,conversion system for tensile and compressive creep test,specimen clamping system and data acquisition system,connecting frame of testing device and environment system,signal receiving and conversion system,and software system.Among them,the software system was developed based on Visual Basic and lookup table algorithm.By analyzing the distribution range and consistency of the interference check points,the correctness of the sampling data was evaluated by the detection system and the data with errors arising caused by the interference were removed.What’s more,this method may make up the deficiency of hardware system and avoid any interference to experimental caused by hardware imperfections.The experimental environment parameters of the system were regulated from-10 to 70 ℃,10% to 98% relative humidity,0.3 to 5.6 m/s wind speed,creep deformation test accuracy up to 0.001 mm,and adjustable data acquisition interval from 1 s to 24 h in multiple gradients.After 14.6 d of tensile creep test and 30 d of compressive creep test,it was found that the deformations of tensile creep and compressive creep were extremely small,and their deformations did not exceed 0.2 mm under a single humidity gradient.In addition,creep in the tensile creep test increased continuously except for the creep during the first moisture absorption,while the creep in the remaining creep stages increased in the moisture absorption stage and decreased in the desorption stage.Except for the creep of the first moisture absorption,compressive creeps increased continuously,and the remaining creep processes were consistent with the mechanical adsorption creep characteristics of the decreasing creep in the hygroscopic phase and increasing creep in the desorption phase.It was proved that the system could monitor,record and display the tensile or compressive creep deformation of wood in real time with long time period,stable,reliable and high accuracy.At the same time,the first tensile-compressive conversion device and loading device of this development greatly reduced the total weight of similar systems and the complexity of experimental operation,providing a new platform for wood tensile and compressive creep testing and research.
作者
王杰
张梓建
万辉
邓书端
董春雷
WANG Jie;ZHANG Zijian;WAN Hui;DENG Shuduan;DONG Chunlei(School of Materials Science and Engineering,Southwest Forestry University,Kunming 650224,China)
出处
《林业工程学报》
CSCD
北大核心
2022年第2期151-158,共8页
Journal of Forestry Engineering
基金
国家自然科学基金(31960291)。
关键词
蠕变环境
拉伸和压缩蠕变
转换系统
自动监测
creep environment
tensile and compressive creep
conversion system
automatic monitoring
作者简介
王杰,男,研究方向为竹木质工程材料;通信作者:董春雷,男,高级实验师。E-mail:dchunlei@swfu.edu.cn。
