| Explosion vessel is widely applied in many fields such as industry,national defense, scientific research and etc.With the advancement of the explosion technique,explosion vessel has been the necessary device for explosion method to produce nanometer material,explosive welding,explosive compaction,explosive forming and so on.As the larger requirement of complex material the wider space is required for the explosion vessel.On the other hand,the contradiction between the blasting noise and residents nearby the plant area or constructions is outstanding day by day.The security protection of the structures was often involved in explosive welding.How to design the structure of the explosion vessel is one of the important research topics in this field.As far as the design and use of large explosion vessel is concerned,finite element method is adopted for structure simulation analysis.It is significant research whether for the structure security estimate prediction or structure parameter optimization.While the numerical simulation method is limited by calculation condition for the artificial factor in structure shop,unit division,boundary condition determination, parameters selection.As for research on large explosion vessel,reliable conclusion can be achieved by combing the numerical simulation and the experiment.Welding wave attenuator in large explosion vessel research is studied in this paper,and the following principle shall be obeyed:safety performance,economy,wave dissipation effect,production efficiency(smoke exhaust efficiency),and durability.The main research content is included as follows:static analysis,post-buckling analysis,dynamic response analysis,solid wall overpressure analysis and production efficiency analysis.Authors mainly adopt LS-DYNA program and theoretical formula to determine the prototype explosive impact load and use LS-DYNA program to the simulate fluid-solid coupling analysis;adopt ANSYS program to analyze the structural strength,structural stability under the shock-wave trap shell earth pressure static load condition,and the instant stress distribution under the shock wave load;and adopt STAR-CD to simulate denotation gas flow within the shell.The main research results are:1.Structural strength under the action of static loadThe covering earth serves as the load to the structure.This thesis adopts the finite element method to analyze the structural strength and deformation characteristics under the action of static load.The research indicates that most equivalent stresses of the structure of that the upper port is 8m or 15m diameter is smaller than the strength design value.The part that the equivalent stress is bigger than the material strength design value is in the position where the stresses concentrate,for example,the joint between plates,door frame and ground beam. Importance shall be attached to in the design.2.Stability of hemispherical shell under the action of static loadThis thesis has simulated and studied the buckling stability under different structure forms on the basis of elastic buckling theory and finite element simulation method.The research indicates that the structural buckling stability safety coefficient is 2.532 when the structure adopts 24 ribs;4.276 when adopts 48 ribs and the upper port is 8m;3.629 when adopts 48 ribs and the upper port is 15m.The test was made by adopting optical projection stripe method to measure the deformation amount of the spherical hell.Further,a test of double overload experiment was made.The results verified that the safety coefficient was more than 2.52 times,while the calculation results achieved by ANSYS program was 4.276 times of the safety coefficient,So the structural is safety.3.Result of dynamic response simulationIt is observed from LS-DYNA numerical simulation that the area over the protection cover is the maximum pressure zone.This thesis has made an analysis on three situations when the explosive dosage is 600kg,800kg and 1000kg respectively.With the increase of explosive dosage,the reflection overpressure extreme value increases gradually,and appears earlier. This thesis adopts LS-DYNA/ANSYS numerical simulation method to calculate and analyze the dynamic response of model and Prototype structure.The result indicates that most structural equivalent stresses under the action of the explosive shock load are smaller than the material strength design value.However,the equivalent stress of some parts calculated by means of finite element method is bigger than the material strength design value due to the effect of stress concentration.Since the synthetic action on most beams and ribs of the structure is not taken into consideration when the explosion response is calculated,the actual stress will be much smaller than the result of finite element simulation.The dynamic load stress test results are the typical stress test results under explosive impact.The first impact stress peak value is the maximum on the spherical shell under the explosive impact effect,the other was tension-compression stress.The vibration stress shall be immediately reduced to below 100 Mpa after 1 to 2 circulations.Obviously,the accumulation of soil can eliminate the vibration of spherical hell.We shall only consider of the positive pressure impact in single explosion when the spherical hell stress check is determined,without consideration of the complex reflection process of the explosive impact wave in the spherical hell because the positive pressure characteristic time is very short.The results of rigid displacement test show that the maximum bottom ring at explosive dosage of 5 kg is only 4 mm displacement(the average is 2mm).The strengthen impact fatigue tests for more than 300 times show that there are no destruction of the overall structure in the spherical hell and 2 part local welding crack.The crack didn't extend any more after the loosed soil was refilled.4.Analysis of smoke exhaust efficiencyIt is obtained by comparing theoretical analysis and three-dimensional numerical simulation that the time proportionality constant between the 1/6model and the prototype is 2.5.Therefore,it could be calculated based on the measured duration in which CO concentration of the 1/6 model will attenuate to 50PPM that it will take 10min for CO concentration of the prototype explosion cave to attenuate to 50PPM when there is light air and the wind direction conforms to the requirement of "lower entrance and upper discharge"; 25min for CO concentration to attenuate to 50PPM when there is light air and the wind direction conforms to the requirement of "upper entrance and lower discharge".It is know from the numerical simulation result that the single upper exhaust outlet is superior to multi-upper exhaust outlets if total exhaust outlet areas of both the former and the latter are the same.As for the single upper exhaust outlet arrangement scheme,if the diameter of the exhaust outlet is unchangeable,the duration in which CO concentration attenuates to the standard state will increase with the increase of exhaust outlet height.5.An anti-blast experiment is made based on this model,explosive dosage is 2 kg,3 kg,4 kg,5 kg is adopted separately,accordingly enlarge the substance to 432 kg,648 kg,864 kg, 1080 kg ANFO explosive,equal to 331 kg,497 kg,663 kg and 828 kg TNT equivalent.We also made strengthen explosive impact fatigue experiment on this model for many times.Up to now,more than 300 times explosion tests with ANFO explosive dosage for 6 kg have made, which was converted to original mode as 1296 kg ANFO and 994 kg TNT equivalent.6.Wave dissipation test results show that the impact wave overpressure on the upright direction of the outlet was subtracted to 50%,to 90%in the direction of 90~angle,the dissipation effect was more obvious.
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