Jianzhong Shang

An Effective Visualization Model for Virtual Maintenance System

Visualization modeling has been recognized as a vital technology of virtual maintenance system. The object modeling and scene graph was used to present and construct virtual maintenance environment. Using object oriented principles and vivid virtual maintenance environment modeling technique; it analyzed and modeled the objects in virtual environment with emphasis on body, group and constraint. Definitions and characters of body, group and constraint were discussed in detail. Then based on graph theory, it presented a scene graph .The scene graph consists of the organization graph, space topology graph and object constraint net graph of the virtual maintenance system. The relationship and structure of them was discussed. It is concluded the method could describe and organize large-scale dynamic virtual environment effectively

Nonlinear Dynamics Modeling and Analysis of Torsional Spring-Loaded Antibacklash Gear with Time-Varying Meshing Stiffness and Friction

Torsional spring-loaded antibacklash gear which can improve the transmission precision is widely used in many precision transmission fields. It is very important to investigate the dynamic characteristics of antibacklash gear. In the paper, applied force analysis is completed in detail. Then, defining the starting point of double-gear meshing as initial position, according to the meshing characteristic of antibacklash gear, single- or double-tooth meshing states of two gear pairs and the transformation relationship at any moment are determined. Based on this, a nonlinear model of antibacklash gear with time-varying friction and meshing stiffness is proposed. The influences of friction and variations of torsional spring stiffness, damping ratio and preload on dynamic transmission error (DTE) are analyzed by numerical calculation and simulation, and the results show that antibacklash gear can increase the composite meshing stiffness; when the torsional spring stiffness is large enough, the oscillating components of the DTE (ODTE) and the RMS of the DTE (RDTE) trend to be a constant value; the variations of ODTE and RDTE are not significant, unless preload exceeds a certain value.

Accelerated Fatigue Bench Test of Driving Axle Housing Based on FEA

By conducting static strength analysis, fatigue life prediction, strain history acquisition and time correlated damage analysis under the FE simulation circumstance, the deducted load spectrum for accelerated fatigue bench test of a special construction vehicle driving axle housing was acquired. The result of bench test shows that the deducted load spectrum can significantly reduce the test period when accurately preserve damage that the part suffering.

Development of a Drilling Fluid Drive Downhole Tractor in Oil Field

This paper proposes a drilling fluid drive downhole tractor, which has the advantages of compact structure, large traction, fast speed and high reliability. The overall mechanical structure of the tractor is introduced, the concrete structures including supporting structure and cushion mechanism are designed. And its all-hydraulic drive continuous propulsion principle is analyzed. Finally the simulation analysis of the tractor operation is carried out to prove that the traction motion scheme is feasible.

Development of a novel self-locking mechanism for continuous propulsion inchworm in-pipe robot

In-pipe robots are usually used to carry many kinds of equipment to operate in the pipeline. In this article, a novel self-locking mechanism for continuous propulsion inchworm in-pipe robot is proposed. The constant power and continuous locomotion principle is obtained by upgrading the traditional pipeline robot. The structure of the inchworm in-pipe robot is designed including self-locking mechanism and telescopic mechanism. The operating principle of self-locking mechanism is analyzed for parameter design and performance evaluation. A new type of hydraulic cylinder series circuit is introduced, which realizes synchronous motion in the related mechanisms of pipe robot. And the dynamic characteristics of the hydraulic cylinders are analyzed and simulated to verify feasibility of the circuit. The prototype is developed to prove that the novel inchworm in-pipe robot can adapt to diameter of 140–180 mm pipe and has 550 N traction ability with the average speed of 0.11 m/s.

Modified rule of mixtures and Halpin–Tsai model for prediction of tensile strength of micron-sized reinforced composites and Young’s modulus of multiscale reinforced composites for direct extrusion fabrication

A modified rule of mixtures is required to account for the experimentally observed nonlinear variation of tensile strength. A modified Halpin–Tsai model was presented to predict the Young’s modulus of multiscale reinforced composites with both micron-sized and nano-sized reinforcements. In the composites, both micron-sized fillers—carbon fibers—and nano-sized fillers—rubber nanoparticles and carbon nanotubes—are added into the epoxy resin matrix. Carbon fibers can help epoxy resins increase both the tensile strength and Young’s modulus, while rubber nanoparticles and carbon nanotubes can improve the toughness without sacrificing other properties. Mechanical experiments and scanning electron microscopy observations were used to study the effects of the micron-sized and nano-sized reinforcements and their combination on tensile and toughness properties of the composites. The results showed that the combined use of multiscale reinforcements had synergetic effects on both the strength and the toughness of the composites.

An assembly sensitivity analysis method based on state space model

Purpose This paper aims to consider a problem of assembly sensitivity in a multi-station assembly process. The authors focus on the assembly process of aircrafts, which includes cabins and inertial navigation system (INSs), and establish the assembly process state space model for their assembly sensitivity research. Design/methodology/approach To date, the process-related errors that cause large variations in key product characteristics remains one of the most critical research topics in assembly sensitivity analysis. This paper focuses on the unique challenges brought about by the multi-station system: a system-level model for characterizing the variation propagation in the entire process, and the necessity of describing the system response to variation inputs at both station-level and single fixture-level scales. State space representation is used to describe the propagation of variation in such a multi-station process, incorporating assembly process parameters such as fixture-locating layout at individual stations and station-to-station locating layout change. Findings Following the sensitivity analysis in control theory, a group of hierarchical sensitivity indices is defined and expressed in terms of the system matrices in the state space model, which are determined by the given assembly process parameters. Originality/value A case study of assembly sensitivity for a multi-station assembly process illustrates and validates the proposed methodology.

Lifetime assessment method for products with dependent competing failures based on copula theory

Based on copula theory and methods, we construct the dependent relationship between the margin distribution functions of the competing failure modes and their joint distribution function through copula function. With the dependent relationship, we study statistical inference method of the life testing with dependent competing failure modes, and found the maximum likelihood estimation (MLE) model for the parameter estimations to evaluate the lifetime of the products. The results and analysis of case studies prove that sample size, proportion of censored samples, proportion of failure samples with masked failure mode, and copula model types have great impact on the accuracy of the lifetime assessment of the products with dependent competing failure modes. And with appropriate test data and right copula modes, method developed in this paper has very good accuracy for the lifetime assessment with dependent competing failure modes. It provides an effective and accurate way to solve the problems of statistical inference of life testing with dependent competing failure modes, and also an accurate way of lifetime assessment for products.

Resonance Characteristic Analysis for Spur Gear Servo Mechanism

Spur gear servomechanism is widely used in photoelectric stabilization platform and other weapon system, its resonance characteristic directly determines the bandwidth, gain and stability of the whole subsystem. Taking Spur gear servo mechanisms as research aim, three degrees of freedom vibration differential equation of gear mesh is theorized, and the resonance equation of the servo mechanism is obtained through Laplace transform, and then the vibration characteristic of stabilization platform is analyzed by numerical analysis. A new kind of resonance frequency analysis method is proposed based on virtual test technology. The digital simulation model of mechanism is created in MATLAB, and then the virtually frequency sweep method is used to excite the resonance characteristic of servo mechanism. The resonance frequency was obtained by analysis of curve of servo mechanism in time domain and frequency domain. Result of numerical analysis and virtual test show that the inertia moment of high speed axes and the mesh stiffness of gear are key assembly and sensitive parameter of the Spur gear servomechanism.

A Method for Path Planning of Hydraulic Manipulator

A method for path planning of hydraulic manipulator is put forward. First, a collision-free path is planned based on the CS (Configuration Space) modeling of nDOFs manipulator. Then the collision-free path is optimized via parabolic transition & linear interpolation, according to the characteristic of hydraulic cylinder. Finally, taking a kind of hydraulic manipulator in engineering for example, the validity of this method is verified using MSC.ADAMS simulation.