Research On Deterioration Model Of Metal Roofing Board Based On Vehicle

With the extensive application of metal roofing board in our country,the corresponding safety problems are getting more and more people’s attention.The accident type of metal roofing board is mainly wind exposure.It is not difficult to find that the metal roofing board itself is not easy to damage in daily use.The reason for the wind exposure accident is mainly the change of the boundary conditions of the metal roofing board.Metal roofing panels are usually connected to the substructure via supports.Bearing as the main boundary condition of metal roofing board can not be obtained visually when damage occurs.For this kind of problem,the industry usually adopts the method based on modal parameters to identify the degraded pattern.For example,long-term health monitoring systems for Bridges or high-rise buildings.But large metal roofing panels,usually more than 10000 square metres,cannot be fitted with long-term health monitoring systems.Therefore,this paper innovatively proposes to adopt the sensor mounted on the moving platform to realize the movable measurement on the metal roofing board.It has the characteristics of high cost performance.First,it is necessary to find the appropriate modal parameters to reflect the damage of the support.Through the establishment of mechanical model and finite element simulation to study whether different dynamic parameters are sensitive to the damage of metal roof plate support,it is found that the base frequency can reflect the health of the support under the moving car,and is not affected by the surrounding support.Considering that a large number of files can be automatically read for modal identification,a data-driven random subspace method is adopted to extract the base frequency.Then the sensitivity of basal frequency to different damage modes was studied.By comparing ABAQUS modeling with the experimental results,the contribution of bearing in different positions to the vertical stiffness was obtained.Basic frequency,as the index of bearing damage state,which is easily affected by temperature.The effect of one day’s temperature change on base frequency is investigated.Through experimental verification,it is found that the frequency of metal roofing substrate is negatively correlated with the temperature.However,within the range of temperature difference within one day,the variation range of base frequency is less than 0.2 Hz,which is far less than the impact of bearing damage.Therefore,the influence of temperature can be ignored for the time being.A field test was carried out on the roofing board of a high-speed railway station ineast China.A damage condition similar to that of the laboratory was found in the field,and the result of basic frequency identification was basically consistent with the conclusion of the laboratory.But problems have also been found.Firstly,in the field test,for the reason that sensor is located between two tracks in the abdomen of the robot,the collected signal’s signal-to-noise ratio is not high,and the modal recognition effect is not as good as that in the laboratory.Secondly,many other types of deterioration patterns were found.However,due to the lack of experiments and studies on the corresponding patterns,the influence of these conditions on the deterioration indicators could not be determined.Therefore,the excitation source can be applied to the robot to improve the signal-to-noise ratio.At the same time,the research on other kinds of deterioration pattern is also carried out.