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Papers - Mitsugi, Jin

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Dynamic analysis of cable-driven flexible multibody systems and its experimental verification

Mitsugi Jin, Senbokuya Yumi

1530 - 1535 1996

This paper presents a method to handle a cable element in the flexible multibody dynamics simulation. The formulation for the cable element successfully separates the material and geometric stiffness matrices irrespective to the choice of rotational parameter. The proposed formulation has been implemented in the previously developed flexible multibody dynamics computer program. An experiment on a simple deployable truss structure whose deployment is controlled by a cable reveals that the proposed method can yield results that are accurate enough for industrial applications.

Direct strain measure for large-deformation analyses of beam structures

Mitsugi Jin

AIAA Journal 33 ( 10 ) 1934 - 1939 1995.10

ISSN 0001-1452

A nonlinear kinematics called the direct strain measure is proposed for large deformation and finite rotation analyses of a two-node Timoshenko beam. The kinematics extracts pure elastic deformations without deriving any virtual frame to describe rigid body motion. Internal force and stiffness matrices are derived to constitute a Newton's method for finding the solution. Computational results show that the present method is valid for Timoshenko beams whose relative angular displacement in an element is less than 0.5 rad.

Finite-element method approach for multibody dynamics

Mitsugi Jin

Nippon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C 61 ( 587 ) 2909 - 2915 1995.07

ISSN 0387-5024

A finite-element-method-based formulation for flexible multibody dynamics, particularly targeting flexible link mechanisms, is proposed. The formulation is composed of two techniques: kinematics of largely displaced Euler beam element and direct coordinate partitioning. The kinematics is basically a corotational method. Direct coordinate partitioning, which is effective only in finite-element-based multibody dynamics, partitions the independent and dependent degrees of freedom hinge by hinge. A computational example on a slider crank with an assembly error shows the validity of the formulation and the developed program, SPADE.

Direct coordinate partitioning for multibody dynamics based on finite element method

Mitsugi Jin

2481 - 2487 1995

An unconventional coordinate partitioning method for flexible multibody dynamics based on the corotational finite element method is proposed. The method establishes the relationship between the nodal degrees of freedom and independent degrees of freedom hinge by hinge, and results in a set of differential equations as the governing equation. Computational examples show that the proposed method can give a physically valid solution for flexible motion during mechanical motion.

Modular cable-mesh deployable structure for large-scale satellite communication antennas

Meguro Akira, Mitsugi Jin, Ando Kazuhide

Electronics and Communications in Japan, Part I: Communications (English translation of Denshi Tsushin Gakkai Ronbunshi) 77 ( 8 ) 90 - 100 1994.08

ISSN 8756-6621

This paper describes a concept and key technologies for a modular mesh deployable antenna. A modular concept is suggested. The advantage of the modular concept and the influence of alignment errors on the surface accuracy are estimated quantitatively. The antenna reflector consists of a mesh surface, a cable network, and deployable truss modules. The cable network comprises three kinds of cables - surface, tie, and back cables. Adjustment of tie cable lengths improves the surface accuracy. Synchronous deployment truss structures are considered as a supporting structure. Their design method, bread board models, and deployment analysis are explained.

Static analysis of cable networks and their supporting structures

Mitsugi J.

Computers and Structures 51 ( 1 ) 47 - 56 1994.04

ISSN 0045-7949

A nonlinear static analysis method for cable structures, particularly emphasizing cable networks, is presented. Cable strains are measured from the current geometry and compressed cables are analytically disassembled with the construction of the equilibrium equation and the stiffness matrix. Finite rotations of cable intersections, referred to as nodes, and cable elements passing through more than two nodes are included in the formulation. An integrated analysis with a linear finite element method is also presented to account for the elastic deformations of supporting structures for the cable networks. The formulation is programmed for a CRAY2 supercomputer using parallel processing to solve the linear equations. Applications of the method used for mesh antenna development are also presented. © 1994.

Access to Document (DOI)

Traversing singularities in nonlinear analyses on cable network structures

Mitsugi Jin

Nippon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A 60 ( 571 ) 867 - 874 1994.03

ISSN 0387-5008

Nonlinear analyses of cable network structures using Newton's iteration often encounter difficulties in solving for a singular stiffness matrix stemming from the tension-stabilizing nature and slackening of cables. This paper presents a solution method, called null space projection, to traverse such a singular linear system in Newton's iteration. In the method, the current unbalance of internal and external forces is projected on the null space of the stiffness matrix and the contributions of null space basis for the variable updating are derived such that the total potential energy is reduced. Numerical example shows that the method successfully traverses singular systems in Newton's iteration process and consequently gives the equilibrium state of the structure.

Pillow distortion analysis for modular mesh antenna

Shimizu Masashi, Ando Kazuhide, Mitsugi Jin

780 - 783 1993

Deployable modular mesh antenna and its surface adjustment

Mitsugi J., Yasaka T.

International Journal of Space Structures 8 ( 1-2 ) 53 - 61 1993

ISSN 0266-3511

The deployable modular mesh antenna is composed of independently fabricated and tested antenna modules to reduce difficulties in ground testing. Each module comprises a metallic mesh shaped by a cable network and a deployable truss structure. This paper states the basic constitution of each module, especially of the cable network, and results of surface shape adjustment simulations and experiments. Employing the present method, reflector distortions after the fabrication can be adjusted by changing cable lengths without any sensitivity analysis. Numerical simulations and experiments clarify that the attainable surface accuracy of a module is determined mainly by the accuracy of the truss structure.

Ground verification of deployment dynamics of large deployable space structures

Meguro Akira, Mitsugi Jin

Journal of Spacecraft and Rockets 29 ( 6 ) 835 - 841 1992.11

ISSN 0022-4650

This paper describes a precise verification procedure for antenna-deployment mechanisms using ground-deployment test data. Ground-deployment tests are carried out for a communication antenna reflector for the Engineering Test Satellite VI (ETS-VI). The antenna-deployment mechanism studied consisted of a bearing, a helical spring, a chassis, and a latch mechanism. The characteristics of individual parts were measured under space and ground conditions. Then the initial characteristic of a deployment mechanism is statistically predicted. Ground verification of a deployment mechanism is usually difficult because of atmospheric and gravitational effects especially at the system level. Therefore, a new verification procedure is employed. Two kinds of suspending system are developed to compensate for gravity effects. The characteristics of a deployment mechanism can be estimated by identifying system parameters for the equation of deployment motion. This estimation procedure covers all development stages, so that a characteristic history of a deployment mechanism can be easily obtained. Atmospheric and gravitational effects on deployment motion are taken into account as system parameters. It is clarified that all mechanical parts retain their initial characteristics during assembly and environmental testing.

Nonlinear static and dynamic analysis method of cable structures

Mitsugi Jin, Yasaka Tetsuo

AIAA Journal 29 ( 1 ) 150 - 152 1991.01

ISSN 0001-1452

Cables are very promising structural elements for space applications since they can be packaged easily in a small volume and function as truss members when in a stretched state. However, an exact analysis of cable structures is difficult because of cable slackening and large deformations. In this paper, a nonlinear cable structure analysis method is derived based on Hamilton's principle and a general purpose cable structure analysis code (CASA) is developed. Higher-order strains are included in the method by taking positions, not displacements, as variables, and cable slackenings are given by a nonlinear, axial stiffness of cable. Nonlinear static and linear dynamic analyses of structures composed of cables and/or trusses can be treated by the present method.

Shape control of the tension truss antenna

Mitsugi Jin, Yasaka Tetsuo, Miura Koryo

AIAA Journal 28 ( 2 ) 316 - 322 1990.02

ISSN 0001-1452

The tension truss antenna is a deployable mesh surface antenna featuring a cable network, called a tension truss, that gives a parabolic shape to the reflective mesh. Cables in the tension truss are rigid enough to prevent their elongation due to the tension, and the number of nodes and cables satisfies the statistically determinant condition. In this paper, surface sensitivity to magnitude and direction errors of the applied force, which gives the tensile force to the tension truss, is evaluated by Monte Carlo simulation. Results show that the surface deformation of a tension truss antenna is smaller than that of an antenna whose cable network is made of flexible cables. It is concluded that the tension truss antenna is a promising candidate for a large space antenna.

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