基于形变测试的分体式恒温试验箱的设计

为双金属片形变测试系统提供可靠的测量环境,设计了基于Labview和PLC的恒温试验箱。该试验箱采用分体式结构来减少振动对测试的影响,其控制系统基于模糊PID控温技术、变频调风速技术以改善测试区温度过冲现象,降低温度的波动性,提高温度均匀性。实验表明:该试验箱操作简单、稳定可靠,在稳定阶段其温度波动性≤±0.1℃,温度均匀性≤±0.5℃,且升降温速度、测试区振动等各项指标均满足形变测试系统的工作要求。

引信天线罩形变遥测图像动态测试方法

针对传统形变测试方法不适用于在高速、高温、高过载的恶劣环境中进行引信天线罩形变动态测试的问题,提出一种基于遥测的非接触式引信天线罩形变动态测试方法。该方法将CMOS图像传感器安装在天线罩内部,对飞行过程中引信天线罩内表面进行在线拍摄,将拍摄到的图像利用无线遥测传输到地面,通过地面图像分析和特征解算获得引信天线罩的变形量曲线。其中变形量计算的关键技术采用了Hough圆检测方法,具有精度高、抗干扰能力强等优点。实验结果表明,该方法满足天线罩动态测试需求,能够测量出天线罩飞行过程中产生的形变量。

一种适于柔性无人机机翼形变的测试方法

文中叙述了一种适用于轻质柔性无人机机翼弹性形变实时测量与监测的系统方法;该方法采用光纤光栅传感器在翼梁上测得的应变数据,通过Ko位移理论公式[1],求出测量点处的实际变形,从而显示出无人机在飞行过程中,受到弯曲、扭转载荷以及弯扭组合载荷的挠度、转角等信息,使地面控制人员能够直观地观察到机翼的变形情况,从而改变控制策略、防止结构破坏危险的发生;该方法已经通过样机地面滑跑试验的验证,光纤测量值经过统计修正,使得地面滑跑试验结果精度高,可靠性好,未来可以作为柔性机翼实时变形测试的实现方法。

基于快速DIC与正则化平滑技术的结构形变测试

传统的有接触结构形变测试存在现场操作困难、多点测试不便、测试成本高等问题,难以应对工程结构形变测试中较为复杂的应用场景。为实现无需人造靶标、可远距离测试且具有较高测试精度的非接触无靶标形变测试,针对采集的结构形变视频图像,引入数字图像相关(Digital Image Correlation,DIC)技术,采用基于Fourier变换的互相关整像素匹配算法与反向组合高斯-牛顿迭代亚像素匹配算法,利用英伟达公司的CUDA并行计算平台,实现结构多点动位移时程的快速测试;基于有限元应变计算与正则化平滑理论,采用位移场后处理方式实现结构连续与非连续应变场的计算。对DIC匹配算法的精度及运算速度、应变算法处理连续与非连续位移场的性能进行对比分析;对超高性能混凝土墩柱抗冲击试验及拱桥吊杆振动试验视频数据进行处理,得到多点位移(频率)测试结果,并与传统测试方法进行对比分析;对砂体抗拔试验及混凝土梁抗弯试验视频进行处理,以云图方式展现位移场与应变场的分布,并与基于逐点最小二乘法的应变测试结果进行对比。研究结果表明:基于快速DIC与正则化平滑技术的非接触结构形变测试方法在结构多点变形、位移频谱及应变场,特别是非连续应变场的测试中得到了较理想结果,具有一定的工程应用价值。

基于工业相机的橡胶软管静液压性能测试方法

文中简单介绍了橡胶软管的长度和弯曲试验性能测试过程,提出用工业相机拍照的方法,自动测试静液压性能。首先对用于自动化测量的工业相机的型号给出了选择依据,然后详细说明了橡胶软管在静液压性能测试中的长度变化率、弯曲角度及弯曲值算法。为橡胶软管承压形变测试的自动化测量提供了一种方法。

传动链节距形变量在线检测的新方法

提出了传动链链节形变量在线测量的新方法。用距离传感器采集测量数据,用数字信号处理器进行数据计算,详尽介绍了计算公式的推导过程,对该公式的精度进行验证。从验证的结果可知,本方法不但结构简单易实现,而且测量的精度高(<=0.08MM),可作为传动链检测系统设计与开发的基础。

智能动态拉压试验机的软件设计

本文介绍了用于智能动态拉压试验机的测控部分软件设计 ,主要解决在满足高速测量需要的同时能够进行实时显示与监控的问题。

位移计测量哑铃形陶瓷样品拉伸μ值和E值误差分析和校正系数推导

本文分析和推导了陶瓷板材拉伸试样用位移计法测量泊桑比μ和拉伸弹性模量 E 的误差和校正系数。陶瓷的拉伸形变测试是一项既重要,难度又较大的工作,特别是在高温下。本分析工作不仅适用于常温拉伸试验,也适用于高温拉伸试验。

Plastic deformation behavior of Mg97Zn1Y2 extruded alloys

The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic tension-compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 （molar fraction, %）, which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1 Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.

Thermo-plasticity of high-strength and high-ductility 7050 aluminum ingot

Thermo-plasticity of homogenized 7050 aluminum ingot was investigated by instantaneous tensile tests conducted at different temperatures. The results show that, with the increase of testing temperatures, the strength decreases, and the plasticity increases firstly and then decreases in homogenized 7050 ingot. When the studied alloy is deformed between 380℃ and 420℃, the deformation resistance is lower and plasticity is better. And the actual heating temperature for ingot before hot extrusion should be controlled between 360 ~C and 400 ~C. At low tensile temperatures, the deformation structure is mainly composed of dislocation substructure. With the increase of testing temperatures, transgranular fracture transforms into intergranular fracture progressively during deformation. At high tensile temperatures, the grain boundaries are weakened, deformation is concentrated at the grain boundaries and the re-orientation of equilibrium phases at grain boundaries appears.

Deformation tests and failure process analysis of an anchorage structure

In order to study the failure process of an anchorage structure and the evolution law of the body＇s defor- mation field, anchor push-out tests were carried out based on digital speckle correlation methods （DSCM）. The stress distribution of the anchorage interface was investigated using the particle flow numerical simulation method. The results indicate that there are three stages in the deformation and fail- ure process of an anchorage structure： elastic bonding stage, a de-bonding stage and a failure stage. The stress distribution in the interface controls the stability of the structure. In the elastic bonding stage, the shear stress peak point of the interface is close to the loading end, and the displacement field gradually develops into a ＂V＂ shape, in the de-bonding stage, there is a shear stress plateau in the center of the anchorage section, and shear strain localization begins to form in the deformation field. In the failure stage, the bonding of the interface fails rapidly and the shear stress peak point moves to the anchorage free end. The anchorage structure moves integrally along the macro-cracl~ The de-bonding stage is a research focus in the deformation and failure process of an anchorage structure, and plays an important guiding role in roadway support design and prediction of the stability of the surrounding rock.

Numerical simulation analysis for deformation deviation and experimental verification for an antenna thin-wall parts considering riveting assembly with finite element method

In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.

New double yield surface model for coarse granular materials incorporating nonlinear unified failure criterion

A new double-yield-sarface （DYS） model was developed to characterize the strength and deformation behaviors of coarse granular materials （CGMs）. Two kinds of deformation mechanisms, including the shear and compressive plastic deformation, were taken into account in this model, These two deformation mechanisms were described by the shear and compressive yield functions, respectively. The Lode angle dependent formulations of proposed model were deduced by incorporating a 3D nonlinear unified failure criterion. Some comparisons were presented between the numerical predictions of proposed model and test data of true triaxial tests on the modeled rockfills. The model predictions are in good agreement with the test data and capture the strain hardening and plastic volumetric dilation of CGMs. These findings verify the reasonability of current DYS model, and indicate that this model is well suited to reproduce the stress-strain-volume change behavior of CGMs in general.

Study on full-length recoverable resin-metal bolts

The paper introduces a kind of full length recoverable resin metal bolts, expounds its structural principle and stress features, and gives some instances in laboratory tests and underground tests. The results show that full length recoverable resin metal bolts can be used for supporting the walls of class Ⅰ～Ⅲ mining gateways, that the anchoring force is 50 kN or so, and that the recoverability rate is more than 80%, thus the supporting effect is better than that of split set bolts.

Permanent deformation response parameters of asphalt mixtures for a new mix-confined repeated load test

The main objective of this work is to propose new mixture response parameters and to compare correlations with rut depths and sensitivity of permanent deformation response parameters based on field extracted cores and lab-mixed duplicates. A new "mix-confined" test is developed and four new parameters for this test are proposed. Correlation coefficients with rut depths and coefficients of variation (sensitivity) are compared between the four new and two existing parameters. Some parameters are recommended to be used for the newly developed test. The results show that, newly developed test can capture the changes of permanent deformation of asphalt mixtures. Only one new parameter (D1 of Stephen Price model) and one existing parameter (flow number, Fn ) have strong correlations with rut depths of asphalt pavements (R2 greater than 0.7) and have relative small sensitivity (coefficient of variation, COV, less than 30%). For polymer modified asphalt mixtures, the parameter D1 rather than Fn should be used. These findings can be used to check the permanent deformation of asphalt mixture during the mix design.

High temperature tensile behaviors of extruded and rolled AZ31 Mg alloy

High temperature tensile ductilities and deformation mechanisms of an extruded and rolled AZ31 Mg alloy were investigated.Elongation-to-failure tests were conducted under constant T-head velocity and constant temperatures ranging from 300℃ to 450℃.Strain-rate-change tests were conducted under varying strain rate from 5×10-5s-1to 2×10-2s-1and constant temperature from 300℃ to 450℃.Experimental results show that the maximum elongation of the AZ31 alloy with an average grain size of about 19μm is 117%at strain rate of 10- 3s-1 and temperature of 450℃.Stress exponent and activation energy were characterized to clarify the deformation mechanisms.The enhanced ductility is dominated by solute drag dislocation creep,and the major failure mechanism is cavity growth and interlinkage.

Exact Solutions,Symmetry Reductions,Painlevé Test and Bcklund Transformations of A Coupled KdV Equation

A coupled KdV equation is studied in this manuscript. The exact solutions, such as the periodic wave solutions and solitary wave solutions by means of the deformation and mapping approach from the solutions of the nonlinear φ4 model are given. Using the symmetry theory, the Lie point symmetries and symmetry reductions of the coupled KdV equation are presented. The results show that the coupled KdV equation possesses infinitely many symmetries and may be considered as an integrable system. Also, the Palnleve test shows the coupled KdV equation possesses Palnleve property. The Backlund transformations of the coupled KdV equation related to Palnleve property and residual symmetry are shown.

An index for deformation controllability of small-volume materials

Mechanical tests on small-volume materials show that in addition to the usual attributes of strength and ductility, the controlla- bility of deformation would be crucial for the purpose of precise plastic shaping. In our present work, a ＂mechanical controlla- bility index＂ （MCI） has been proposed to assess the controllability of mechanical deformation quantitatively. The index allows quantitative evaluation of the relative fraction of the controllable plastic strain out of the total strain. MCI=0 means completely uncontrollable plastic deformation, MCI=∞ means perfectly controllable plastic shaping. The application of the index is demonstrated here by comparing two example cases： 0.273 to 0.429 for single crystal A1 nanopillars that exhibit obvious strain bursts, versus 3.17 to 4.2 for polycrystalline A1 nanopillars of similar size for which the stress-strain curve is smoother.