Fatigue Life Study Of Rolled-Steel Pallet

With the growth of the economy, developing of the technology and upgrading of the industry, the need for high-end steel product rolled-steel is growing quickly. The characters of rolled-steel transportation which is long-altitude, high-weight and the product place is inner land determines that the best method is by train. Safe and reliability of the cargo loading and fixing is the base of the quick and efficient transportation. The rolled-steel pallet is used more and more widely for its recycled, easy-installing, easy-loading-unloading and less influence of the safety.The now using method to test the rolled-steel pallet is to measure the stress of the test point at the shock situation to ensure that the maximum stresses of all the points are less than the allowable stress of the material we use. The pallet will be announced safe if it can meet the demand we ask for. Meanwhile, the mental material will be damaged by another kind of invalid which is called fatigue comparing the static stress damage. During the whole using life of the pallet, the operation condition when the pallet is under changing load is the main statue of the pallet and the shock condition when the pallet is under the maximum load of its life is the unusual statue. The pallet in the operation condition suffers the changing load because of the vibration of the car coming from the irregularity of the rail which leads the fatigue damage of the rolled-steel pallet. The study of calculation of the fatigue life is meaningful for the safety and economy.In this thesis, the rolled-steel pallet which is analyzed as a model is designed and made in Sichuan PanZhiHua Steel Corp. The fatigue life of the rolled-steel pallet is calculated to help judge the safety as the following strategies.(1) Accessing the load time series of the rolled-steel pallet.Build the vehicle dynamics model of the car carrying rolled-steel pallet and rolled-steel on it using the multi-body dynamics software SIMPACK. Simulate and calculate to get the load time series of the rolled-steel pallet under the real car-running situation and irregularity of rail.(2) Stress analysis of the rolled-steel pallet.Simulate the stress of the rolled-steel pallet under the standard load by interactive calculation with the 3D modeling software SolidWorks, finite element creating software Hypermesh and finite element simulation software ANSYS.(3) Damage analysis of each fatigue test point and life prediction of the rolled-steel pallet.Access the tress time series of each test point by simulation under the load time series. Calculate the fatigue damage in the test distance of each point according to the British rules BS7608:1993<Fatigue Design and Assessment of Steel Structures> using the rain flow counting method.Predict the fatigue of pallet according to the fatigue damage of each test point. The calculation method is convinced believable with the result is similar to the life of the pallet in real using situation.The calculation method can be used in the future to test the pallet ensuring the safety and determining the service life.(4) Structure optimization of the rolled-steel pallet.Choose the fittest method after analyzing all the different method to extend the fatigue life of the pallet which is convinced to extend the life of the rolled-steel pallet apparently.In this article, a new method of test the rolled-steel pallet which is based on the theory of the multi-body dynamics and fatigue damage is put forward to ensure the safety. The method is proved effective by comparing the simulation result and the real data of the rolled-steel pallet made in PanZhiHua Steel Corp. This method can be used in the test of other pallet to ensure the safety in the future.