• Journal of Korean Association for Spatial Structures
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• v.16 no.2
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• pp.39-45
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• 2016

Membrane structure is a system that is stabilized by maintaining a tensile state of the membrane material that originally cannot resist the bending or pressure. Also, it is a system that allows the whole membrane structure to bear external loads caused by wind or precipitation such as snow, rain and etc. Tension relaxation phenomenon can transpire to the tension that is introduced to the fabric over time, due to the innate characteristics of the membrane material. Thus, it is important to accurately understand the size of the membrane tension after the completion of the structures, for maintenance and management purposes. The authors have proposed the principle of theoretically and indirectly measuring the tension by vibrating the membrane surface with sound waves exposures against the surface, which is compartmentalized by a rectangular boundary, and by measuring the natural frequency of the membrane surface that selectively resonates. The authors of this paper measured the tension of preexisting membrane structure for its maintenance by using the developed portable measurement equipment. Through analyzing the measurement data, the authors review the points that should be improved and the technical method for the new maintenance system of membrane tension.

• 한국공간정보시스템학회:학술대회논문집
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• 2004.05a
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• pp.222-229
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• 2004

This study purports to analyze equally stressed surfaces in tension-membrane structures through a geometrically nonlinear approach. It adopts the formulation of a 4-node quadrilateral isoparametric plane stress element considering the orthotropic characteristic of membrane textures. Tension structures, which include cables and tension membranes, such as a cable dome initially exhibit unstable conditions because no initial internal stiffness such as bending stiffness is present. Such a structural system requires prestressing to the tension members to attain a stable state. A tension-membrane structure retains a stable three dimensional curved surface as a structural shape. This analytical process for finding the geometry is referred to as Shape Finding Analysis. In order to assess the validity of this study, we examine equally stressed surfaces of saddle and catenary shape shell structures and carry out pertinent stress analyses

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.171-178
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• 2008

This paper is concerned with the development of a measurement system using field measuring device which will give the membrane stress of the membrane structures. Up to this point, several techniques on measurement of membrane stresses has been proposed and some have been used in the fields, but accuracy of the measured stresses to be far from reliable one. Such situation has not been changed until recent days, we do not have the measurement device on which we can depend. On top of that, due to the different properties in cross directions for material of the membrane, the stress in the warp direction is different from that in the fill one. A new method is proposed to measured membrane stresses in two different direction separately, where instead of membrane stresses directly, an external force perpendicular to the membrane to be applied. A portable device can measure the applied force and the displacement. A special testing bed to be fabricated to accommodate $50cm{\times}50$ manbrane specimen which can apply 5 ton load in two orthogonal direction. A special device using push-pull gage was developed. To measure the membrane stresses in warp and fill direction separately, a different length of the tips are used. The measuring device which can called tension meter, can be calibrated on the testing bed, and optimized the length and shape of tip.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.10a
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• pp.298-305
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• 1998

The purpose of this study is to propose the method of determining the initial fabric membrane structures surface and membrane patterning procedures. Tension structure, such as, fabric membrane structures and cable-net, is stabilized by their initial prestress and boundary condition. The process to find initial structural overall shape of tension structures produced by initial prestress called Shape Finding or Shape Analysis. One of the most important factor for the design of membrane structures is to search initial smooth surface, because unlike steel or concrete building elements which resist loads in bending, all tension structure forces are carried within the surface by membrane stress or cable tension. To obtain initial surface of fabric membrane element in large deformation analysis, the membrane element is idealized as cable using a technique with Force-density method. and that result is compared with well-known nonlinear numerical method, such as Newton-raphson method and Dynamic relaxation method. The shape resulting from Force-density method has been dealt with as the initial membrane shape and used patterning procedures.

• The Korean Journal of Physiology
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• v.2 no.1
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• pp.39-45
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• 1968

Recently, in this department, pressure-displacement curve and breaking tension of dog and human tympanic membrane were studied using intact, fresh or dried tympanic membrane attached to external auditory meatus. However, physical property, proper elasticity-Young Modulus, of the tympanic membrane has not been clarified yet. Present study is attempted to further clarify proper Young Modulus of tympanic membrane, and to distinguish possible difference between layer of stratum radiatum and layer of stratum circulare of tympanic membrane in breaking tension and in Young Modulus. Tympanic membrane was excised from sacrificed dog, and preparation was made into the size of approximately 1 mm in width and 3 mm in length. In fresh or dried tympanic membrane, which was dried at $80^{\circ}C$ for 24 hrs., some preparations were made along the long axis parallel to the fibers of radial direction, and others were made along the long axis perpendicular to the radial fibers-circular direction. Breaking tension and displacement according to loading, were measured and Young Modulus was calculated in tympanic membrane preparations under the different experimental conditions. Results obtained are summarized as follows : 1. Young Modulus of fresh tympanic membrane in radial direction was $6.57{\times}10^8\;dyne/cm^2$, and that of fresh preparation in circular direction was $1.68{\times}10^8\;dyne/cm^2$. The Young Modulus of fresh tympanic membrane in radial direction resembles to that of silk and whale moustache. In dried tympanic membrane, Young Modulus of preparation of radial direction was $30.2{\times}10^8\;dyne/cm^2$ and that of preparation in circular direction was $25.0{\times}10^8\;dyne/cm^2$. 2. Breaking tension of fresh tympanic membrane was 44.9 gm/mm in radial preparation, and 7.9 gm/mm in circular preparation. In dried tympanic membrane, breaking tension was 46.7 gm/mm in preparation of radial direction, and 17.2 gm/mm in preparation of circular direction. 3. Much smaller breaking tension of the circular preparation-one fifth to the radial preparation-seemed to be responsible for the higher incidence of circular fiber breaking in tympanic membrane performation caused by trauma or sudden change in atmospheric pressure. 4. The correlation seemed to be very close between breaking tension and Young Modulus in tympanic membrane.

• Journal of Korean Association for Spatial Structures
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• v.13 no.4
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• pp.83-90
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• 2013

PTEF membranes are used for roofing materials of membrane structures. PTEF is the abbreviation of Poly-tetra Fluotide-ethylene. These materials are consisted of fiberglass weave and polyetrfluoroethylene coating. Also, PTEF membranes have some problems of structural capacity by wind or snow load, etc. In this study, sensor housings using lead switches are bonding in PTFE membranes, Monitoring to changes tension and tear damages are studied using radio frequency. If tension is received on edged membranes, bonded lead switches of sensor housings will be destroyed by changes tension, and these become to send signals of damages at the connected radio frequency system with increased tension. Study of these functional membrane materials will be contributed to prevent water leakage and long-term maintenance of membrane structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.268-275
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• 1999

The purpose of this study is to propose the method of determining the initial pneumatic membrane structures surface and stresses and displacements. Tension structure such as pneumatic membrane structures is stabilized by their initial prestress and air pressure. The process to find initial structural overall shape of tension structures produced by initial prestress called shape finding. One of the most important factor for the design of membrane structures is to search initial smooth surface, because unlike steel or concrete building elements which resist loads in bending, all tension structure forces are carried within the surface by membrane stress. The result for initial surface of pneumatic membrane element and maximum displacement in large deformation in analysis is compared with well-known nonlinear numerical method such as Newton-raphson method and dynamic relaxation method

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.4
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• pp.290-300
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• 2009

The existing numerical methods on the vertical membrane breakwater have employed a linear analysis where the variable membrane tension occurring during membrane motions is assumed to be very negligible compared to the initial tension. In the present study, a quasi-nonlinear analysis is attempted such that the temporary tension of the membrane is substituted by the average tension for a wave period that is sought by an iterative calculation. The results showed that with the increase of the wave period the reflection coefficients appeared larger and the transmission coefficients smaller compared to the results of the linear analysis. The application of the quasi-nonlinear analysis also showed that the performance of the structure is closely dependent on the horizontal deformation of the membrane. In order to suppress the horizontal deformation, it may be required to take the larger initial tension of the membrane or to put additional mooring lines in the middle of the vertical faces of the membrane. But for theses methods to be effective, a largely sized surface float should be installed to secure enough buoyancy to support such downward forces.

• Journal of Korean Association for Spatial Structures
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• v.16 no.1
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• pp.35-42
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• 2016

Until recently, almost all ETFE film structures that have been erected is the cushion type because there are problems at lower allowable strength under elastic range and viscosity behaviour such as creep and relaxation of ETFE films under long-term stresses. But the number of tension type structures is currently increasing. This paper proposes the stretch fabrication of ETFE film to verify the applicability of ETFE films to tensile membrane structures. First of all, to investigate the possibility of application on tensile membrane structures, the stretch fabrication test is carried out, and it is verified that it is possible to increase the yield strength of the film membrane structures. After simulating the experiment also carries out an analytical investigation, and the effectiveness of the elasto-plastic analysis considering the viscous behavior of the film is investigated. Finally, post-aging tension measurement is conducted at the experimental facilities, and the viscosity behavior resulting from relaxation is investigated with respect to tensile membrane structures.

• Journal of Korean Association for Spatial Structures
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• v.19 no.1
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• pp.109-116
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• 2019

In this paper, the shape adjustment algorithm of the spoked wheel cable structures with retractable membrane system is studied. The initial tension of the membrane or cable is necessary to form the structure and its value is determined by the design shape. However, due to internal and external environmental influences, its shape may be different from the initial designed shape. In the case of the cable structures covered in this study, tension adjustment is necessary to maintain the designed shape because it influences the tension of the cable depending on the state of the retractable membrane. Therefore, we proposed an adjustment algorithm of an initial shape based on the force method. The effectiveness and validity of the methodology were examined through the applicable cable structures. The results of the shape adjustment analysis of the symmetric spoked wheel cable model were reliable and accurate results were obtained.