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This paper aims to carry out assembly variation analysis for mechanisms with compliant joints by considering deformations induced by manufactured deviations. Such an analysis procedure extends the application area of direct linearization method (DLM) to compliant mechanisms and also illustrates the dimensional interaction within multi-loop compliant structures.

By applying DLM to both geometrical equations and Lagrange’s equations of the second kind, an analytical deviation modeling method for mechanisms with compliant joints are proposed and further used for statistical assembly variation analysis. The precision of this method is verified by comparing it with finite element simulation and traditional DLM.

A new modeling method is proposed to represent kinematic relationships between joint deformations and parts/components deviations. Based on a case evaluation, the computational efficiency is improved greatly while the modeling accuracy is maintained at more than 94% rate comparing with the benchmark finite element simulation.

The Equilibrium Equations of Incremental Forces derived from Lagrange’s equations are proposed to quantitatively represent the relationships between manufactured deviations and assembly deformations. The present method extends the application area of DLM to compliant structures, such as automobile suspension systems and some Micro-Electro-Mechanical-Systems.

This study aims to study the dynamic characteristics of a helical geared rotor-bearing system with composite material rotating shafts.

A finite element model of a helical geared rotor-bearing system with composite material rotating shafts is developed, in which the rotating shafts of the system are composed of composite material and modeled as Timoshenko beam; a rigid mass is used to represent the gear and their gyroscopic effect is taken into account; bearings are modeled as linear spring-damper; and the equations of motion are obtained by applying Lagrange’s equation. Natural frequencies, mode description, lateral responses, axial responses, lamination angles, lamination numbers, gear mesh stiffness and bearing damping coefficients are investigated.

The desired mechanical properties could be constructed using different lamination numbers and fiber included angles by composite rotating shafts. The frequency of the lateral module decreases as the included angle of the fibers and the principal shaft of the composite material rotating shaft increase. Because of the gear mesh stiffness increase, the resonance frequency of the coupling module of the system decreases, the lateral module is not influenced and the steady-state response decreases. The amplitude of the steady-state lateral and axial responses gradually decreases as the bearing damping coefficient increases.

The model of a helical geared rotor-bearing system with composite material rotating shafts is established in this paper. The dynamic characteristics of a helical geared rotor-bearing system with composite rotating shafts are investigated. The numerical results of this study can be used as a reference for subsequent personnel research.

The dynamic characteristics of the geared rotor-bearing system had been reported in some literature. However, the dynamic analysis of a helical geared rotor-bearing system with composite material rotating shafts is still rarely investigated. This paper shows some novel results of lateral and axial response results obtained by different lamination angles and different lamination numbers. In the future, it makes valuable contributions for further development of dynamic analysis of a helical geared rotor-bearing system with composite material rotating shafts.

This paper aims to propose preliminary design models of actuator housing that enable various geometries to be compared without requiring detailed knowledge of the actuator components. Aerospace actuation systems are currently tending to become more electrical and fluid free. Methodologies and models already exist for designing the mechanical and electrical components, but the actuator housing design is still sketchy.

The approach is dedicated to linear actuators, the most common in aerospace. With special attention paid to mechanical resistance to the vibratory environment, simplified geometries are proposed to facilitate the generation of an equivalent formal development. The vibratory environment imposes the sizing of the actuator housing. Depending on the expected level of details and to vibration boundary conditions, three levels of modeling have been realized.

This paper shows that the vibrations induced by aircraft environment are not design drivers for conventional hydraulic actuators but can be an issue for new electromechanical actuators. The weight of the latter can be optimized through a judicious choice of the diameter of the housing.

This approach is applied to a comparison of six standard designs of linear actuator geometries after validation of the consistency of the different models. Early conclusions can be drawn and may lead to design perspectives for the definition of actuator architecture and the optimization of the design.

This paper has demonstrated the importance of the vibratory environment in the design of linear actuator housing, especially for electro-mechanical actuators with important strokes. Developed analytical models can be used for the overall design and optimization of these new aerospace actuators.

The paper proposes to deal with the problems concerning the N‐phase (N+1)‐wire system with sinusoidal voltage sources and nonlinear loads. In the model of the N‐phase voltage source the inner impedance has been included. The problem of the optimization of working conditions of the system is a minimization of RMS value of its line currents as well as their distortions caused by nonlinear loads.

The solution of this problem is based on the frequency domain. It is obtained by means of Lagrange's multipliers and the suitable measurement experiment.

After optimization source currents are sinusoidal with minimized RMS values. After connection of the designed compensator to the system under research the phase currents are equal to determined active currents.

This method can be used for some classes of nonlinear loads, i.e. for systems with inertialess (non‐reactive) elements, which consume the active power of the basic harmonic of the voltage source and where the currents of the system are periodical. The mentioned power is an additional constraint of the presented minimization.

The working point of the system can be obtained by means of the compensator LC, RLC or (RLC,‐R). It will always be a linear one and its structure consists of two components: elements with parameters determined for the basic harmonic and the filter for elimination of the higher harmonics caused by nonlinear loads.

The presented method has been generalized for N‐phase (N+1)‐wire systems.

Stiffened plates have been widely used in civil, marine, aerospace engineering. As a kind of thin-walled structure operating in complex environment, stiffened plates mostly undergo a variety of dynamic loads, which may sometimes result in large-amplitude vibration. Additionally, initial stresses and geometric imperfections are widespread in this type of structure. Furthermore, it is universally known that initial stresses and geometric imperfections may affect mechanical behavior of structures severely, particularly in dynamic analysis. Thus, the purpose of this paper is to study the stress variation rule of a stiffened plate during large-amplitude vibration considering initial stresses and geometric imperfections.

The initial stresses are represented in the form of initial bending moments applying to the stiffened plate, while the initial geometric imperfections are considered by means of trigonometric series, and they are assumed existing in the plate along the z-direction exclusively. Then, the dynamic equilibrium equations of the stiffened plate are established using Lagrange’s equation as well as aforementioned conditions. The nonlinear differential equations of motion are simplified as a two-degree-of-freedom system by considering 1:2 and 1:3 internal resonances, respectively, and the multiscale method is applied to solve the equations.

The influence of initial stresses on the plate, stresses during internal resonance is remarkable, while that is moderate for initial geometric imperfections. (Upon considering the existence of initial stresses or geometric imperfections, the stresses of motivated modes are less than the primary mode for both and internal resonances). The influence of bidirectional initial stresses on the plate’s stresses during internal resonance is more remarkable than that of unidirectional initial stresses. The coupled vibration in 1%3A2 internal resonance is fiercer than that in internal resonance.

Stiffened plates are widely used in engineering structures. However, as a type of thin-walled structure, stiffened plates vibrate with large amplitude in most cases owning to their complicated operation circumstance. In addition, stiffened plates usually contain initial stresses and geometric imperfections, which may result in the variation of their mechanical behavior, especially dynamical behavior. Based on the above consideration, this paper studies the nonlinear dynamical behavior of stiffened plates with initial stresses and geometrical imperfections under different internal resonances, which is the originality of this work. Furthermore, the research findings can provide references for engineering design and application.

A transient dynamic finite element procedure is presented for failure analysis of centrally‐impacted laminated composite pretwisted rotating plates. A nine‐noded, three‐dimensional degenerated composite shell element is developed and used for the present finite element formulation. Effects of transverse shear deformation and rotary inertia are included. The strength‐of‐material type failure criteria are adopted and the “total ply discount” approach is used as the stiffness reduction model. The dynamic equilibrium equation is derived by applying Lagrange’s equation of motion and the investigation is carried out for moderate rotational speeds for which the Coriolis effect is negligible. The modified Hertzian contact law is utilized to compute the contact force between the impactor and the laminated plate. Impact failure analyses of pretwisted rotating plates are performed to investigate the effects of angle of twist, rotational speed and laminate configuration.

This paper aims to study a dynamic analysis of a double-helical geared rotor system with oil-film bearing.

A finite element model of a double-helical geared rotor system with oil-film bearing is developed, in which a rigid mass is used to represent the gear and the Timoshenko beam finite element represents the shaft; the equations of motion are obtained by applying Lagrange’s equation. Natural frequencies, Campbell diagram, lateral responses, axial responses, bearing stiffness coefficients, bearing damping coefficients and bearing force are investigated.

Natural frequencies and Campbell diagram of a double-helical geared rotor system with oil-film bearing are investigated. An increased helical angle enhanced the axial response of the system and reduced its lateral response. The distance between the node and bearing affected the lateral response magnitude on the node. The farther away the gear pair was from the central part of the shaft, the higher the system’s resonance frequency became. The different gear pair position has a significant influence on the bearing stiffness coefficient and bearing force, but it just has a little effect on the bearing damping coefficient.

The model of a double-helical geared rotor system with oil-film bearing is established in this paper. The dynamic characteristics of a double-helical geared rotor system with oil-film bearing are investigated. The numerical results of this study can be used as a reference for subsequent personnel research.

Although the dynamics characteristics of geared rotor bearing system have been reported in some literature, the dynamic analysis of a double-helical geared rotor-bearing system is still rarely investigated. This paper showed some novel results that lateral and axial response results are obtained by the different helical angle and different gear positions. In the future, it makes valuable contributions for further development of dynamic analysis of a double-helical geared rotor-bearing system.

The subject of aeroelasticity is not well provided with text books and this makes the present book all the more valuable. One difficulty in writing such a text book is that although aeroelasticity is often regarded as a highly specialized subject and tends to be avoided by the average aeronautical engineer, yet it embraces a very wide field of study covering matters as diverse as linear aerofoil theory, both steady and unsteady, some boundary layer effects, structural theory for distortion of the aircraft components, problems of servo analysis and mathematical methods for the solution of large numbers of linear equations with real and complex coefficients. Thus, although the book contains nearly 500 pages it is correctly entitled ‘An Introduction …’ and the author presents each of his subjects with diversions into pure mathematics where necessary. These mathematical sections include introductions to Lagrange's equations, matrices and Laplace transformations.

The purpose of this paper is to define the conditions for a failsafe coupling of parts when using adaptation and low-frequency vibrations. A model enables us to determine the reaction at the contact points of parts and time-based contact conditions changes. Therefore, the conditions of jamming parts can be defined in the process of conjugation.

A mathematical model describing the trajectory of the part mass center in robotic assembly is created. An experimental equipment is also presented in the paper. Convergence of theoretical and experimental results that characterize the reliability of processes is estimated.

The mathematical model of the connection process dynamics is found in the form of Lagrange’s equations of the second kind.

Applying low-frequency vibration and the adaptive gripper is proposed to extend technological capabilities of robotic assembly.