Fatigue Life Analysis And Simulation Study Of Hydraulic Impactor Hammer

Hydraulic breaking hammer is the device used in special vehicle，whose piston isdriven by hydraulic system to impact the drill rod to make the concrete and other thingsbroken. With the development of infrastructural facilities construction and coal, hydraulicbreaking hammer is widely used in more and more construction sites. So, it is important tomake the design program perfect to decrease cost and increase reliability to improve itscompetitive power. Researches were carried out as the follows:Firstly, on the basis of introduction of structure and working principle of hydraulicbreaking hammer, differential equations were built about the piston and valve core ofhydraulic braking hammer. And then the hydraulic model was built with the hydraulicsimulation software DSHplus. Through the simulation, some parameters of its workingcondition were gained. The3D model of hydraulic breaking hammer was built. Themulti-body Dynamics model was built. Co-simulation was executed with RecurDyn andMatlab/Simulik. The results were compared with the experiment’s results, which reflect themuti-model was correct. From the Co-simulation, the boundary condition was gained forfinite element analysis.Secondly, the3D model was simplified and the mesh model of FEA was built withHyperMesh. Material, properties and loading condition which gain from multi-bodyanalysis were added to the mesh model. LS-Dyna was used to solve the FEA model. Theresults show that most parts’ stress of hydraulic breaking hammer was under the yieldlimits. The drill rod’s stress is nearly reaching to the yield stress limits. At the same time,the stress and strain’s time history of every part was gained for fatigue analysis.Then, the fatigue characteristic, process of crack growth, definition of fatigue life,fatigue damage and S-N curve were introduced. Rainflow counting method andPalmgren-Miner criterion were used in the set of fatigue life calculation software whichwas developed using C#language on the basis of calling the API of Femap.Finally, Fatigue life of every part of hydraulic breaking hammer was calculated with the software. In order to confirm the results were right, fe-safe were used to calculate thefatigue life of hydraulic breaking hammer. Under the comparison of the two sets of results,the error is within8%. What’s more, the analysis results are consistent with the engineeringpractice. All of these reflect that the developed software and the methods of fatigueanalysis were approved reliable to calculate the hydraulic hammer’s fatigue life.Computer aided engineering is widely used in the study of special vehicle design andoptimize. The methods and the software about the fatigue life calculation of hydraulicbreaking hammer based on computer were provided, which may bring some positiveinfluence on the development of hydraulic breaking hammer.