摘要：Ls-DYNA software is adopted to conduct research of numerical simulation on hot stamping of side impact beam to calculate the temperature field distribution, stress field distribution, forming limit diagram （FLD） figure, etc. in the course of hot stamping so as to predict and analyze the formability of parts. ProCAST software is employed to conduct research of numerical simulation on solid quenching course concerning hot stamping to calculate temperature field distri- bution of tools and component of muhiple stamping cycles. The results obtained from numerical simulation can provide significant reference value to hot stamping part design, formability predication and tools cooling system design.

摘要：Despite the non-contact underwater explosion phenomena(UNDEX)have been studied for decades and several numerical methods have been proposed in literature,its effects on military structures,especially composite ones,are even nowadays matter of *** early design phases,it is not always possible to verify the shock resistance of hull structures modelling the whole phenomenon,in which fluid,gas and solid properties must be properly set in a fully coupled fluid-structure interaction(FSI)numerical *** ones are extremely complex to set,computationally demanding and certainly not suitable for everyday design *** this paper,a simplified finite element(FE)model,easy to use in an early design phase,is ***,the structure and the fluid are *** this approximation,the fluid behaviour is simplified,using special finite elements,available in a commercial software *** choice reduces the computational time and numerical efforts avoiding the problem of combining computational fluid dynamics(CFD)and FE domains and equations in a fully coupled fluid-structure interaction model.A typical parallel body block of a minesweeper is modelled,using two-dimensional multi-layered shell elements to properly account for the composite materials *** the fluid instead,three dimensional volumetric elements,directly coupled to the structural elements,are *** addition,the same calculation is performed,modelling separately fluid in the CFD environment and structures in the finite element ***,realizing a fully coupled fluid-structure interaction *** results obtained by applying both numerical models are compared with the structural response measured on board of a composite ship during a full-scale shock *** simplified proposed procedure provides results in satisfactory agreement with experiments,allowing the validation of the *** are discussed and differences with the real phenomenon and fully coupled CFD+

摘要：The cyclic symmetry and local fine-mesh technology were adopted in the establishment of numerical simulation model for inner gear spin-forming. And the processing experiment was proceeded to verify the reliability of the established model. The simulation result indicates that besides radial and axial flows, there also exists rather large tangential flow, which results in an increase of forming force in tangential direction. Furthermore, the un-uniform deformation of metal during spin-forming would cause forming defects, such as underfill in tooth fillet region and indentation on the outside spun part.

摘要：Wind barriers have attracted significant attention as an effective measure to ensure train safety under ***,in past decades,the influence of structural parameters such as the height and ventilation ratio of wind barriers on the difference of the average pressure coefficient between the train windward and leeward surface(ΔCp)has not been fully *** determine the influence of the interaction among the three factors,namely the wind barrier height(H),ventilation ratio(R),and distance to the train(D),twenty five numerical simulation cases with different structural parameters were considered based on an orthogonal *** shear stress transfer(SST)k-ωturbulent model was employed to calculate the wind pressure coefficients,and the calculation accuracy was validated by using wind tunnel *** results indicated that with an increase in R,ΔCp first decreased and then increased,andΔCp decreased while D ***,with the increase in H,ΔCp first increased and then ***,these three factors must be considered during the installation of wind ***,according to a range analysis(judging the relative importance of the three factors intuitively),the three factors were ranked in the following order:R>H>*** on a variance analysis,R was found to be of high significance toΔCp,followed by H,which was significant,whereas D had relatively insignificant ***,the optimal values of R and H were determined to be 20%and 110 mm,*** when R=40%,H=85 mm,the train was relatively unsafe under these such *** findings of this study provide significant guidance for the structural design of wind barriers.

摘要：The application of hard/soft composite structure in personnel armor for blast mitigation is relatively practical and effective in realistic protection engineering,such as the shell/liner system of the ***,there is still lacking a reliable experi-mental methodology to effectively evaluate the blast mitigation performance when the structure directly contacts the protected target,which limits the development of protection *** this paper,we proposed a new method to evaluate experi-mentally and numerically the blast mitigation performance of hard/soft composite *** blast mitigation mechanism is *** hard/soft structures were composed of ultra-high molecular weight polyethylene(UHMWPE)composite and expanded polyethylene(EPE)*** field explosion experiment,a 7.0 kg trinitrotoluene(TNT)spherical charge is used to generate blast waves at a 3.8 m stand-off distance.A pressure test device is designed to support the tested structure and measure the transmitted blast pressure pulses after passing through the *** results indicate that the hard/soft structures can mitigate the blast pressure pulse into the triangular pressure pulse,through making the pulse profile flatter,reducing the pressure amplitude,and delaying the pulse arrival ***,the combination of 7 mm UHMWPE composite and 20 mm EPE foam can reduce the blast pressure amplitude by 40%.Correspondingly,the finite element simulation is also carried out to understand the blast mitigation *** numerical results indicate that the regulation for blast pressure pulses mainly complete at the hard/soft interface,which is attributed to the reflection of pressure waves at the interface and the deformation of the soft layer compressed by the hard layer possessing kinetic ***,based on these analyses,the corresponding theoretical model is proposed,and it can well explain the experimental and numerical *** study is meaningful for e

摘要：Due to autorotation,samaras can fly efficiently and stably to be dispersed over a great distance under various weather ***,we provide a quantitative analysis of the dynamic stability of free-falling maple samara(Acer grosseri Pax)and verify whether they are dynamically stable as *** and kinematic parameters were obtained based on the existing experimental data of the maple *** the linearized equations of motion were derived,and the stability derivatives were calculated by a computational fluid dynamics *** techniques of eigenvalue and eigenvector analysis were also used to examine the stability *** is found that there are five natural modes of motion of the maple seed:one stable oscillatory mode,one fast subsidence mode,one slow subsidence mode,and two neutral stable *** two neutral modes are manifested as the seed moving horizontally at a low speed under *** show that the maple seed has dynamic stability in sustaining the steady autorotation and descent,exhibiting a minor horizontal motion when *** findings can beapplied to biomimetic aircraft.

摘要：A new severe plastic deformation method for manufacturing tubes made of AZ31 magnesium alloy with a large diameter was developed,which is called the TCESE(tube continuous extrusion−shear−expanding)*** process combines direct extrusion with a two-step shear−expanding *** influences of expanding ratios,extrusion temperatures on the deformation of finite element meshes,strain evolution and flow velocity of tube blanks during the TCESE process were researched based on numerical simulations by using DEFORM-3D *** results show that the maximum expanding ratio is 3.0 in the TCESE *** deformation of finite element meshes of tube blanks is inhomogeneous in the shear−expanding zone,and the equivalent strains increase significantly during the TCESE process of the AZ31 magnesium alloy.A extrusion temperature of 380°C and expanding ratio of 2.0 were selected as the optimized process parameters from the numerical simulation *** average grain size of tubes fabricated by the TCESE process is approximately 10μ*** TCESE process can refine grains of magnesium alloy tubes with the occurrence of dynamic ***(0001)basal texture intensities of the magnesium alloy tube blanks decrease due to continuous plastic deformation during the TCESE *** average hardness of the extruded tubes is approximately HV 75,which is obviously improved.

摘要：In order to conform to dimensional tolerances, an efficient numerical method, displacement iterative compensation method, based on finite element methodology （FEM） was presented for the wax pattern die profile design of turbine blades. Casting shrinkages at different positions of the blade which was considered nonlinear thermo-mechanical casting deformations were calculated. Based on the displacement iterative compensation method proposed, the optimized wax pattern die profile can be established. For a A356 alloy blade, substantial reduction in dimensional and shape tolerances was achieved with the developed die shape optimization system. numerical simulation result obtained by the proposed method shows a good agreement with the result measured experimentally. After four times iterations, compared with the CAD model of turbine blade, the total form error decreases to 0.001 978 mm from the orevious 0.515 815 mm.

摘要：Blast wall can prevent vehicles from approaching the protective building and can reduce the destructive power of shock wave to a certain ***,majority of studies on blast walls have some *** explosion test data are *** exsiting studies focus on the propagation of shock wave and the influence of blast wall on the propagation of shock *** on the main parameters of blast wall design is meagre,such as the design of safety distance,the distance from the blast wall to the protective building,height and width of the blast *** paper uses the finite element programme LS-DYNA to design the blast *** analyze the convergence of the finite element model and to determine the mesh size of the model,this paper establishes several finite element models with different sizes of meshes to verify the ***,the overpressure distribution of the shock wave on the protective building is simulated to implement the blast wall *** geometric parameters of the blast wall are preliminarily *** the influence of the safety distance on the overpressure of the building surface is mainly discussed,so as to determine the final design *** the overpressure is less than 2 kPa,it is considered that there will be no damage to people caused by flying ***,the blast wall height is 3 m,the thickness is 1 m,and the safety distance is 35 *** proposed method is used to demonstrate the design method,and the final design parameters of the blast wall can thus be used for reference.

摘要：This article discusses the development of the numerical methods of gas flow coupled with heat transfer,and introduces the fluid net-works method for rapid prediction of the performance of the composite cooling structures in turbine *** reliability of these methods is verified by comparing experimental *** a HPT rotor blade,a rapid prediction on the internal cooling structures is first made by using the fluid network analysis,then an assessment of aerodynamic and heat transfer characteristics is *** on the network analysis results,three ways to improve the design of the cooling structures are tested,i.e.,adjusting the cooling gas flow mass ratios for different inner cooling cavities,reducing the flow resistances of the channel turning structures,and improving the local internal cooling structure geometries with high temperature *** the verification of full three-dimensional gas/solid/coolant conjugate heat transfer calculation,we conclude that the modified design can make the overall temperature distribution more even by significantly reducing the highest temperature of the blade surface,and reasonably matching the parameters of different coolant *** results show that the proposed calculation methods can remarkably reduce the design cycle of complex turbine blade cooling structure.