Sensor Optimal Placement For Risk Identification Of Gantry Crane Structure

As the crane is one of the important machines for industrial production and logistic industry.that whether it is running safety is directly related to the secutity of the enterprise’s production and the national economy. With the rapid development of the national economy,the crane has been widely uesd in and abroad,at the same time,the requirement for it’s safety increasing rapdily along with the crane’s optimizing process for larger-scale structure and diversified fuction.The health monitoring system of crane has also been attached more attention to by the development of the crane’s manufacturing industry and the widespread use of crane.However.considering the bearing capacity of the crane structure in normal working conditions.the traditional health mornining system only can monitor the accumulated damage of the structure but not the special dangerous working condiions,such as,lifting weights inclinedly and skewed forward under the action of typhoon. With a large stiffness which is different form the flexible bridges,crane’s normal failure modes are always the unexpected collapse and derailment which are not caused by accumulated damage is quiet different form the failure modes of the normal structural.Therefore,setting the mode,stress and strain as the monitoring paramenters for the traditional health monitoring system does not make many sense for the risk warning and safety assessment of the crane.According to the situation above,it is urgent to perfect the crane’s risk monitoring system.Using the intelligent sensing technology to monotor the risk of the crane caused by the accumulated damage and combining the working condition and the failure modes of the crane in monitoring the unexpected failure condition of the crane are two important parts in crane’s risk monitoring system.With the improved risk monitoring system of the crane,it is possible to recoginze and judge the risk timely and accuracily,so as to put forward the risk treatment stragety and reduce the possibility of the accidents. With the gantry crane as the research object,this paper put forward a new risk monitoring concept of the crane which is more scientific,comprehensive and related more closely to the risk of the crane. With the new concept of the risk monitoring of the crane,the framework of the health monitoring system of the crane in risk identity has been put forward.The sensor placement of the new risk monitoring system of the crane has also benn optimized with the modified harmony search algorithm in this paper.Firstly,as the traditional health monitoring system for crane’s risk caused by accumulated damage is not intact,combing with the concept of the risk of structure and the characteristics of the crane structure,the new concept of crane’s risk monitoring system based on it’s working situation was divided into two parts:the first is aimed at monitoring crane’s risk based on it’s state,the other is aimed at monitoring crane’s risk caused by it’s accumulated damage.Secondly,the layout plan for monitoring crane’s working environment was obtained refering to the Design rules for cranes and Safety rules for lifting appliances.For monitoring crane’s working space,the arrangement plan for mornitoring instrument was obtained by applying the rail-mounted crane collision avoidance system developed by our research group.Moreover,sensor placement for monitoring crane’s own state which an important part of the crane’s risk monitoring systemis was acquired by numerical simulation with the large finite element analysis software ANSYS.All these date accumulated form the risk monitoring system based on crane’s statue provide the theory basis and the data sources for intimely identifying risks and effectively dealing with risks.Thirdly,generally,the stress and displacement sensors are usually arrangemented at the danger points with high stress and displacement.A opinion that the stress and placement sensors can be used to identify crane’s risk based on it’s own state.To identify crane’s risk based on it’s own state,using comprehensive evaluation method,a method of optimal monitoring stress and placement sensor location was proposed.According to the characteristics of gantry crane’s structure,working environment,analysis result of ANSYS,the factor set affecting sensor placement was determinded.And the weight of each factor was determined based on Analytical Hierarchy Process(AHP).The fuzzy support matrix was constructed by using the distance mensure matrix of the proposed measure points.Based on fuzzy mathematics methods,factors of the factor set were classified and standardized. At last,the selected monitoring points of stress and placement sensors were optimized according to the comprehensive evaluation method.Finally,the acceleration sensors are used to monitor crane’s risk caused by accumulated damage.The sensor optimal placement procedure for monitoring crane’s risk caused by accumulated damage was optimized by means of the commercial mathematical software MATLAB and the superiority in convergence rate and stability of the optimized procedure was proved with the steel truss girder bridge.The improvement is carried out through three aspects:the number of modes is determined by the grediant of ROC;the number of sensors is determined using the basic harmony algorithm;the improvement of harmony algorithm is conducted by perfecting the initial values of the harmony memory set and setting three paramenters change along with the iteration.A better layout plan for sensors monitoring crane’s risk caused by accumulated damage was figured out with the proposed optimal sensor placement procedure that brings a better balance between economy and reliability.