Assessment of local strain field in adhesive layer of an unsymmetrically repaired CFRP panel using digital image correlation

The present study focuses on experimental investigation of through the thickness displacement and strain field in thin adhesive layer in single sided (unsymmetrical) patch repaired CFRP (carbon fiber reinforced polymer) panel under tensile load. Digital image correlation (DIC) technique is employed to acquire the displacement and strain (longitudinal, peel and shear) field. Experimental determination of shear transfer length based on shear strain field obtained from DIC is introduced to estimate the optimum overlap length which is an essential parameter in patch design for the repair of CFRP structures. Further, DIC experiment with magnified optics is performed to get an insight into complex and localized strain field over thin adhesive layer especially at critical zones leading to damage initiation. The failure mechanism, load displacement behavior, damage initiation and propagation are closely monitored using DIC. The influence of patch edge tapering on strain distribution in adhesive layer is also investigated. The DIC successfully captures the global and localized strain field at critical zones over thin adhesive layer and further helps in monitoring the damage based on strain anomalies. Strains are found to have maximum magnitude at the patch overlap edge and the shear strain level in adhesive layer is higher than the peel strain. Normal tapering increases the peel strain and has negligible influence on shear strain level in adhesive layer. The recommended overlap length is found to be consistent with the recommendation in the literature. Whole field strain pattern and the overlap length obtained from experiment are further compared with the finite element analysis results and they appear to be in good coherence.     

Recovery planning of industrial robots based on semantic information of failures and time-dependent utility

Industrial robots are required to recover from temporary errors and continue operations under a changing environment. In this paper, we propose a recovery planning system that considers the semantic information behind errors during robotic actions. In order to establish general repair strategies for feasible recovery plans under uncertainties, the proposed system uses a conceptual graph based on case grammar and a Bayesian network that is dynamically constructed according to the semantic information. In addition, we tackle the problem that the wealth of the recovery plan depends on the uncertainty of execution costs against the deadline at the production site. The proposed system controls the decision model by using a time-dependent utility. We demonstrate the effectiveness of the proposed system through simulations of assembly tasks by multiple robots.     

工程轮胎修补胶国产化研制

根据矿山井下工程轮眙的使用要求,结合引进TIP.TOP公司修补胶的物性炼点,经过反复试验研制出的自制修补胶片物性接近与进口胶片,且成本低廉,完全满足了工程轮胎修补需要。     

水泥混凝土路面压浆技术处理的实践与认识

通过对某城市快速干道水泥混凝土路面出现的沉陷、错台、唧泥，致使板块脱空、扇动等现象的介绍，采用压浆技术进行维修养护。通过施工实践的回顾与总结，提出新的认识，这对今后水泥混凝土路面维修养护具有一定的参考意义。     

KJC－2型矿山机械工程检修车

ＫＪＣ－２型矿山机械工程检修车是集机械设备状态监测与故障诊断研究实验室和修理车间两大功能于一体的大型自行式设备．本文介绍其基本结构与装备、性能参数、适用范围和使用条件．     

实施信号设备状态修降低设备故障率

介绍了信号设备状态修,如何实施信号设备状态修和状态修带来的经济效益.     

延长井下工程轮胎使用寿命的途径

总结了管理井下工程轮眙使用维护的经验,提出通过工况选型、使用维护、调整利用等途径,有效延长工程轮胎使用寿命,从而降低消耗,提高矿山整体经济效益。实践证明行之有效。     

Repair of damaged aluminum truss joints of highway overhead sign structures using FRP

An innovative repair technique is introduced for aluminum truss-type highway overhead sign structures, using fibre-reinforced polymer (FRP) sheets. The welded k-joints are typically subjected to excessive fatigue-induced cracking under the effects of wind and moving traffic. The repair technique proposed in this paper utilizes longitudinal FRP layers bonded to the diagonals and wrapped around the main chord to form alternating v-patterns, followed by additional circumferential layers for anchorage. Eight tests were conducted on four full-scale specimens. Weld lines at the junction between diagonals and main chord were ground to simulate a 90% loss of joint strength. After repair, diagonals were loaded to failure in tension. The study showed that full strength of the welded joints was restored using carbon-FRP sheets. Only 70% of joint strength was restored when using glass-FRP. The strengthening technique is particularly sensitive to quality control during installation. A field application using the proposed technique was successfully completed by the New York State Department of Transportation for a cracked aluminum truss over Route 88 in NY State.     

图形电镀夹膜修理方法

图形电镀已经是PCB制造加厚铜的主要方式,夹膜问题是此工艺流程的一大顽疾,本文为各位同仁介绍一种有效、简便、实用的修理夹膜的方法.