Study on the coupling calculation method for the launch dynamics of a self-propelled artillery multibody system considering engraving process

The launch dynamics theory for multibody systems emerges as an innovative and efficacious approach for the study of launch dynamics,capable of addressing the challenges of complex modeling,diminished computational efficiency,and imprecise analyses of system dynamic responses found in the dynamics research of intricate multi-rigid-flexible body systems,such as self-propelled artillery.This advancement aims to enhance the firing accuracy and launch safety of self-propelled artillery.Recognizing the shortfall of overlooking the band engraving process in existing theories,this study introduces a novel coupling calculation methodology for the launch dynamics of a self-propelled artillery multibody system.This method leverages the ABAQUS subroutine interface VUAMP to compute the dynamic response of the projectile and barrel during the launch process of large-caliber self-propelled artillery.Additionally,it examines the changes in projectile resistance and band deformation in relation to projectile motion throughout the band engraving process.Comparative analysis of the computational outcomes with experimental data evidences that the proposed method offers a more precise depiction of the launch process of self-propelled artillery,thereby enhancing the accuracy of launch dynamics calculations for self-propelled artillery.

Transfer matrix method for determination of the natural vibration characteristics of elastically coupled launch vehicle boosters

The analysis of natural vibration characteristics has become one of important steps of the manufacture and dynamic design in the aerospace industry. This paper presents a new scenario called virtual cutting in the context of the transfer matrix method of linear multibody systems closed- loop topology for computing the free vibration characteristics of elastically coupled flexible launch vehicle boosters. In this approach, the coupled system is idealized as a triple-beam system-like structure coupled by linear translational springs, where a non-uniform free-free Euler-Bemoulli beam is used. A large thrust-to-weight ratio leads to large axial accelera- tions that result in an axial inertia load distribution from nose to tail. Consequently, it causes the development of significant compressive forces along the length of the launch vehicle. Therefore, it is important to take into account this effect in the transverse vibration model. This scenario does not need the global dynamics equations of a system, and it has high computational efficiency and low memory requirements. The validity of the presented scenario is achieved through com- parison to other approaches published in the literature.

Numerical simulation of the coupled dynamics model of the projectile engraving process

The projectile engraving process directly influences the projectile motion in-bore and impacts the firing accuracy,firing safety,and barrel life of the gun.For this reason,attention has been focused on this research topic.To address the limitations of the“instantaneous engraving”hypothesis adopted in the classical interior ballistic theory,the VUAMP user subroutine,one of ABAQUS's secondary development interfaces,is utilized in this paper to realize the modeling and numerical simulation of a coupled dynamics model of the projectile engraving process.In addition to facilitating engineering applications,a polynomial fitting formula of the engraving resistance obtained by simulation is proposed and then used as a supplement to establish a closed and solvable interior ballistic model considering the projectile engraving process.By comparing with test data,the simulation accuracy of the coupled dynamics model is verified.Simulation results reveal that the engraving process takes 3.8 ms,accounting for 26%of the whole launch process,which takes 14.6 ms,demonstrating that the process is not instantaneous.The results of this paper can serve as a reference for future studies on the coupled solution of the projectile engraving process and interior ballistics of guns or gun-like equipment.

路面谱随机激励下的轮式发射系统动力学建模与仿真

轮式发射系统行驶动力学建模与仿真是其动力学性能和试验设计的前提和基础,日益提高的轮式发射系统动态性能迫切需要一种快速高效的大型多体系统动力学计算方法。本文采用多体系统传递矩阵法建立了轮式发射系统的动力学模型,给出了相应的拓扑图和动力学方程,此外,通过快速傅里叶逆变换重构了平行车轮的路面不平度,结合蒙特卡罗方法对随机路面激励下轮式发射系统的动力学特性进行了模拟和讨论分析结果表明,随着路面不平度级别和行驶速度的增加,轮式发射系统的振动加速度幅值越大,在正常车速下,路面激励对车体的影响远大于车速。模态试验和行驶试验验证了动力学建模和仿真的正确性本文可拓展到其他包含概率不确定性的多体系统动力学建模和分析.

Tool-tip vibration prediction based on a novel convolutional enhanced transformer

Superior surface finish remains a fundamental criterion in precision machining operations,and tool-tip vibration is an important factor that significantly influences the quality of the machined surface.Physics-based models heavily rely on assumptions for model simplification when applied to complex high-end systems.However,these assumptions may come at the cost of compromising the model's accuracy.In contrast,data-driven techniques have emerged as an attractive alternative for tasks such as prediction and complex system analysis.To exploit the advantages of data-driven models,this study introduces a novel convolutional enhanced transformer model for tool-tip vibration prediction,referred to as CeT-TV.The effectiveness of this model is demonstrated through its successful application in ultra-precision fly-cutting(UPFC)operations.Two distinct variants of the model,namely,guided and nonguided CeT-TV,were developed and rigorously tested on a data set custom-tailored for UPFC applications.The results reveal that the guided CeT-TV model exhibits outstanding performance,characterized by the lowest mean absolute error and root mean square error values.Additionally,the model demonstrates excellent agreement between the predicted values and the actual measurements,thus underlining its efficiency and potential for predicting the tool-tip vibration in the context of UPFC.

Letter of thanks for IJMSD's JCR debut in 2024

Dear Readers,Authors,Reviewers,Editorial Board Members,Editorial Office Members,We are pleased and honored to inform you that,according to the 2024 Journal Citation Reports(JCR)from Clarivate released on June 20,2024,the International Journal of Mechanical System Dynamics(IJMSD)received its first Journal Impact Factor of 3.4(2023).IJMSD ranks 42nd out of 180 journals in the Engineering,Mechanical category(Q1,top 23.1%),and 39th out of 170 journals in the Mechanics category(Q1,top 22.6%).

人造系统动力学多元系统传递矩阵法初探

人造系统也称人工系统,是人类为了达到某种目的而构造的系统,例如各种加工系统、运输系统、电力系统、机械系统、武器系统等.现代科学、技术和工程已发展到从全系统动力学角度分析、提高人造系统设计、加工、试验、评估和运用全生命周期能力,以获得期望性能的工程产品的高级阶段,其目标是建立精确的人造系统动力学数学模型并对其快速数值求解,从而准确、快速地预测和提高系统性能[1].坦克、舰艇、飞机、运载火箭、卫星、汽车、高铁、发电机、电动机、精密机床等各种现代人造系统发展,推动了科技和人类文明进步,是一个国家重大战略布局和综合实力的象征,是国计民生和国家安全的关键标志.由于缺乏先进的人造系统动力学快速计算等理论与软件,现代人造系统发展至今仍面临提高设计性能、提高加工质量、降低试验评估成本、保障运用安全的严峻挑战.

Multibody system transfer matrix method:The past, the present, and the future

The multibody system transfer matrix method(MSTMM),a novel dynamics approach developed during the past three decades,has several advantages compared to conventional dynamics methods.Some of these advantages include avoiding global dynamics equations with a system inertia matrix,utilizing low‐order matrices independent of system degree of freedom,high computational speed,and simplicity of computer implementation.MSTMM has been widely used in computer modeling,simulations,and performance evaluation of approximately 150 different complex mechanical systems.In this paper,the following aspects regarding MSTMM are reviewed:basic theory,algorithms,simulation and design software,and applications.Future research directions and generalization to more applications in various fields of science,technology,and engineering are discussed.

Improved incremental transfer matrix method for nonlinear rotor-bearing system

Rotor system supported by nonlinear bearing such as squeeze film damper(SFD)is widely used in practice owing to its wide range of damping capacity and simplicity in structure.In this paper,an improved and effective Incremental transfer matrix method(ITMM)is first presented by combining ITMM and fast Fourier transform(FFT).Afterwards this method is applied to calculate the dynamic characteristics of a Jeffcott rotor system with SFD.The convergence dificulties incurred caused by strong nonlinearities of SFD has been dealt by adopting a control factor.It is found that for the more general boundary problems where the boundary conditions are not at input and output ends of a chain system,the supplementary equation is necessarily added.Additionally,the Floquet theory is used to analyze the stability and bifurcation type of the obtained periodic solution.The semi-analytical results,including the periodic solutions of the system,the bifurcation points and their types,are in good agreement with the numerical method.Furthermore,the involution mechanism of the quasi-periodic and chaotic motions near the first-order translational mode and the second order bending mode of this system is also clarified by this method with the aid of Floquet theory.

Optimal design of 6-DOF vibration isolation platform based on transfer matrix method for multibody systems

The structure parameters of 6-degree of freedom(DOF)vibration isolation platform have a significant effect on its performance.To make the designed vibration isolation platform perform well,non-dominanted sorting genetic algorithm version II(NSGA-II)was applied to optimize its structure based on the transfer matrix method for multibody systems.Firstly,the Jacobian matrix of 6-DOF vibration isolation platform was solved based on kinematics.Secondly,the transfer equation of 6-DOF vibration isolation system was established by the linear transfer matrix method for multibody systems.And the formula of its natural frequency was derived according to the boundary conditions of the system.Thirdly,the manipulability index was constructed based on a dimensionless Jacobian matrix.And a new performance index function was established considering the influence of dynamic isotropic and legs mass.Fourthly,genetic algorithm(GA)and NSGA-II were used to optimize the structure of the 6-DOF vibration isolation platform under the same conditions,respectively.It showed that NSGA-II had higher optimization efficiency,better calculation accuracy and shorter optimization time than that of GA.Finally,NSGA-II was adopted for multi-objective optimization design of 6-DOF vibration isolation platform based on the constraint conditions.Optimal Pareto solutions were obtained,which provides structural parameters for subsequent design work.Therefore,the proposed optimization method and the performance index in this paper provide a theoretical basis for the optimal design of relevant vibration isolation mechanism.

Hybrid multibody system method for the dynamic analysis of an ultra‐precision fly‐cutting machine tool

The dynamics of an ultra‐precision machine tool determines the precision of the machined surface.This study aims to propose an effective method to model and analyze the dynamics of an ultra‐precision fly‐cutting machine tool.First,the dynamic model of the machine tool considering the deformations of the cutter head and the lathe head is developed.Then,the mechanical elements are classified into M subsystems and F subsystems according to their properties and connections.The M‐subsystem equations are formulated using the transfer matrix method for multibody systems(MSTMM),and the F‐subsystem equations are analyzed using the finite element method and the Craig-Bampton reduction method.Furthermore,all the subsystems are assembled by combining the restriction equations at connection points among the subsystems to obtain the overall transfer equation of the machine tool system.Finally,the vibration characteristics of the machine tool are evaluated numerically and are validated experimentally.The proposed modeling and analysis method preserves the advantages of the MSTMM,such as high computational efficiency,low computational load,systematic reduction of the overall transfer equation,and generalization of its computational capability to general flexible‐body elements.In addition,this study provides theoretical insights and guidance for the design of ultra‐precision machine tools.

Dynamic Simulation of Space Debris Cloud Capture Using the Tethered Net

Space debris,especially the space debris cloud,has threatened severely the safety of future space missions.In the framework of multibody system dynamics,a computational approach is proposed in this study to investigate the dynamics of net deployment and capture of space debris cloud using this net subject to large overall motions and large deformations.To obtain high simulation fidelity of capturing space debris cloud,the gradient deficient beam element of the absolute nodal coordinate formulation(ANCF)is employed to discretize threads which are woven into the net.The normal contact force between the net and the debris cloud and among debris particles is computed by using the penalty method.Some deployment examples are presented to investigate the influences of shooting velocity of bullets and microgravity as well as the angle between the traveling direction of the net and the microgravity direction on the deployment characteristics of the tethered net.Other capturing examples are given to clarify the effect of the deployment area of the net at the moment it starts to contact with the debris cloud on the capture rate and to demonstrate the effectiveness of the proposed approach for capturing space debris cloud using the net in microgravity conditions.

Vibration characteristics analysis of tank gun barrel with nonuniform cross-section

The firing accuracy of a tank gun is affected significantly by the flexural motion of the barrel.For the purpose of satisfying the requirement of efficiently and accurately dynamic analysis and optimization of the tank gun barrel to ensure it has good dynamic characteristics and firing accuracy,the high-fidelity dynamic model of a tank gun barrel is developed according to the transfer matrix method for multibody system which has features of high degree of stylization and high computational speed.The transfer matrix of the non-uniform Euler-Bernoulli beam(NU-EB beam)is deduced from governing differential equations of motion utilizing the differential transform method.The orthogonality of augmented eigenvectors for the NU-EB beam is proven which can be used for its exact dynamics response analysis using the modal method.In allusion to the tank gun barrel with non-uniform cross-section,the barrel is modeled as a combination of several uniform and non-uniform transverse vibrating Euler-Bernoulli beams.The overall transfer equation and matrix of the tank gun barrel are established according to the automatic deduction theorem of the overall transfer equation of multibody system.The present method is proven to be effective by comparing the computational results to those in published literatures.The vibration characteristics of a tank gun barrel with a non-uniform cross-section are analyzed accurately and are verified by the modal test.

Eigenvalue analysis of planar linear multibody system under conservative force based on the transfer matrix method

The linear multibody system transfer matrix method(LMSTMM)provides a powerful tool for analyzing the vibration characteristics of a mechanical system.However,the original LMSTMM cannot resolve the eigenvalues of the systems with ideal hinges(i.e.,revolute hinge,sliding hinge,spherical hinge,cylindrical hinge,etc.)or bodies under conservative forces due to the lack of the corresponding transfer matrices.This paper enables the LMSTMM to solve the eigenvalues of the planar multibody systems with ideal hinges or rigid bodies under conservative forces.For a rigid body,the transfer matrix can now consider coupling terms between forces and kinematic state perturbations.Also,conservative forces that contribute to the eigenvalues can be considered.Meanwhile,ideal hinges are introduced to LMSTMM,which enables the treatment of eigenvalues of general multibody systems using LMSTMM.Finally,the comparative analysis with ADAMS software and analytical solutions verifies the effectiveness of the proposed approach in this paper.

Generation mechanism and control of high-frequency vibration for tracked vehicles

A crawler system provides much larger ground contact,leading to excellent terrain adaptability.Due to its structural characteristics,high‐frequency vibration proportional to the vehicle speed is generated during the driving process.This is a result of the polygon and rolling effects between the track and the wheels.A field test of a tracked vehicle is performed to monitor movement signals of the chassis and a rocker arm.Their corresponding power spectral density distributions confirm the correctness of the frequency‐calculation equation.Then,a novel elastic track tensioning device with a damper is designed as a cushion between the idler and the chassis.Depending on its geometry,the equivalent damping coefficient for a dynamic model is evaluated.Subsequently,the damping is altered in response to different operating conditions by a hybrid damping fuzzy semiactive control system.The controller accounts for both chassis and track vibration.Based on the transfer matrix method for multibody systems,a dynamical model of the track system is developed.Control performances are evaluated using two numerical simulations of obstacle crossing and off‐road driving operations.Results indicate that the proposed semiactive tensioner is substantially better than the conventional one.This paper provides a novel feasible scheme for vibration reduction of tracked vehicles.

Core/shell magnetite/copolymer composite nanoparticles enabling highly stable magnetorheological response

Magnetorheological fluids(MRFs)have been successfully used in a variety of smart control systems,but are still limited due to their relatively poor settling stability.Herein,a core/shell‐structured Fe_(3)O_(4)/copolymer composite nanoparticle is synthesized as a new candidate material for stimulus‐responsive MRFs to tackle the limitation of the long‐term dispersion stability.Aniline‐co‐diphenylamine copolymers(PANI‐co‐PDPA)are loaded onto the surface of Fe_(3)O_(4) nanoparticles,providing a lighter density and sufficient active interface for the dispersion of magnetic particles in the carrier medium.The features of the Fe_(3)O_(4)/copolymer composite nanoparticles,including morphology,compositional,and crystalline properties,are characterized.An MRF is prepared by suspending Fe_(3)O_(4)/copolymer composite nanoparticles in a nonmagnetic medium oil,and its rheological properties are assessed using a controlled shear rate test and dynamic oscillation tests using a rotational rheometer.Rheological models including the Bingham model and the Herschel–Bulkley model are fitted to the flow curves of the MRF.The obtained Fe_(3)O_(4)/copolymer composite shows soft‐magnetic properties,as well as greater density adaptability and higher stability,compared to Fe_(3)O_(4).Moreover,the sedimentation testing provides information about the dispersion stability characteristics of MRF and shows a good correlation with high‐stability magnetorheological(MR)response.The Fe_(3)O_(4)/copolymer‐based MRF with a tunable and instantaneous MR response is considered a promising material for smart control applications.

Letter of thanks for IJMSD's indexing in ESCI

Dear Authors/Reviewers/Editorial Board Members/Editorial Office Members/Readers,We are delighted to inform you that the International Journal of Mechanical System Dynamics(IJMSD)was officially indexed by Emerging Sources Citation Index(ESCI)on June 27,2023,after being indexed by Inspec,Scopus,DOAJ,Dimensions,and some other databases.We would like to take this opportunity,on behalf of the IJMSD Editorial Board,to extend our gratitude and sincere appreciation for your significant contributions and support to IJMSD.

IJMSD: A novel journal devoting to promote the progress of modern science, technology and industry by enhancing the capabilities of mechanical system dynamics

From the Stone Age to modern industry,the development of me-chanical systems has driven human civilization and the progress of science and technology.Inferior dynamic performances related to manufacturing precision,mobility,comfort,reliability,and safety have become the bottlenecks restricting the development of con-temporary industrial products,which can be regarded as complex and integrated mechatronical systems composed of many subsystems with highly coupled dynamical behaviors.With the advent of the fourth industrial revolution and the widely used complicated and integrated products,it has been found clearly that quasi‐static or local dynamics study can no longer capture the critical features of contemporary mechanical systems.