Bing Zhao

• Ph. D.
• Associate Professor at Shanghai Jiao Tong University

Stress distribution on a membrane surface plays a key role in the structural safety and bearing capacity of an inflatable membrane structure, especially for the state under service condition. This paper presents an in situ method to determine the stress distribution of an inflatable membrane structure by using a force-finding method based on measur...

As a kind of typical air-inflated membrane structure, ethylene–tetrafluoroethylene (ETFE) cushion has become one of the most essential engineering structures in recent decades, especially in the field of large-span spatial structures. This study experimentally investigates the mechanical properties and structural behaviors of ETFE cushion structure...

ETFE (ethylene tetrafluoroethylene) air-inflated cushion structure has become one of the primary choices for being roofs and facades of large-span structures. Prior to the load bearing stages, it is required to firstly inflate the ETFE cushion envelope to gain the desired initial geometrical height and structural stiffness. This paper thus proposes...

Apart from the well-known excellent basic properties, the mechanical behaviors of ETFE (ethylene tetrafluoroethylene) foils are more fundamental for the refined design and analysis of ETFE membrane structures. This paper investigates the nonlinear mechanical properties of ETFE foils at varying strain rates (0.01 to 10 min⁻¹) through a combination o...

Air-supported membrane structures, lauded for their flexibility and ease of construction, find increasing applications in large-span projects. However, their susceptibility to wind-induced damage, particularly under gusty conditions, necessitates advanced analysis techniques to ensure structural integrity. This paper introduces a bidirectional coup...

As a deployable mechanism and structural integrated component, the shape memory polymer composites (SMPCs) will inevitably be damaged during folding and storage. However, damage effects on the shape memory behaviour of the SMPCs lack thoroughly investigations. This article aims to research the entire shape memory process of the SMPCs with the consi...

Air cushions have been widely utilised as roofs and facades for large-span buildings owing to their advantages such as ultra-light weight and aesthetic appearance. The dynamic performance of air cushions, which is a typical fluid-solid interaction problem, is complex, because the top layer, bottom layer, and inner air are highly coupled. However, t...

Various strength criteria have been extensively used in the structural design of stratospheric airships. However, it is still a critical challenge to accurately predict the failure strength for ensuring structural safety due to the complex mechanical behaviors of multi-layer composite envelope materials under various loading environments. This arti...

Thermally-induced shape memory polymer composites (SMPCs) have the capability to self-deploy when stimulated by a specific temperature. As a basic component of deployable truss structure, SMPCs thin-wall circular tubes will undergo complex non-linear deformation and changing thermal boundary conditions during application. This article aims to resea...

The paper investigates the mechanical properties of coated polyester fabrics in biaxial monotonic tensile tests. The nonlinear behaviors of the constitutive parameters within the full-stress range were in detail analyzed, and a new constitutive model based on the specific coupling relationships between the uniaxial and biaxial flexibilities was pro...

To reveal the central tearing behaviors and propagation mechanisms of the architectural non-crimp fabric (NCF) composites with an initial crack, a microscopic finite element (FE) model was proposed and developed to simulate the tearing propagation process of materials in this paper. Firstly, the experimental program including the central crack tear...

This paper presents a new fractional constitutive model to reveal the nonlinear and viscoelastic properties of fabric composites under normal loading conditions. The uniaxial tensile tests for warp-knitted non-crimp fabric (NCF) composites under different strain rates were carried out, and their nonlinear characteristics and quasi-yield behaviors u...

To comprehensively understand the wind-induced response of air-supported membrane structure, a structural health monitoring system is designed and firstly installed on a pneumatic membrane sports hall with large span. Consisting of four sub-systems, this system was applied to perform a long-term in-situ monitoring. Structural vibration data of oute...

Porous materials with well-defined periodicity are commonly encountered in biological and synthetic structures and exhibit a wide range of behaviors, ranging from negative Poisson’s ratios, to high energy absorption and acoustic damping. Recently, the response of these systems has been shown to be enhanced by mechanical instabilities that lead to s...

Temperature is a paramount factor for shape memory polymer composites (SMPCs) to implement their shape recovery functions and present their high specific stiffness when applied in aerospace deployable structures. However, many existing studies focused on the thermo-mechanics and shape memory behaviors of SMPC were established based on uniform tempe...

In order to reveal shear deformation mechanisms of architectural non-crimp fabric (NCF) composites, detailed shear stiffness-nonlinearities for a typical coated warp-knitted NCF composite under shear-tension coupling loading were studied from experimental investigation and FEA models. Shear-tension coupling effects on shear stiffness of the NCF com...

To study the thermal performance of an enclosed dome with double-layered PTFE membrane with aerogel-glass wool insulation mats, a comprehensive on-site test was carried out. Twenty-two wireless thermometers were used to monitor the temperature of key positions during a clear to cloudy day in summer. Solar irradiance was recorded as well. A numerica...

Background The counterweight-balanced column bending test (CWB-CBT) was developed by Fernandez and Murphey [1] to counter the gravity sag issue of column bending test and generate a better uniform bending stress state in characterizing thin composites’ bending behavior at large curvatures. When analyzing the test data the original processing method...

This study investigates the large deformation bending properties of a single‐ply fabric reinforced polymer composite (SpFRPC) by the innovative counterweight balanced column bending test (CWB‐CBT) and microscopic analysis. The influences of temperatures and asymmetric weave structure on SpFRPC's bending properties are emphasized. In glassy state at...

In order to further clarify the shear mechanisms and shear-tension coupling effects of warp-knitted non-crimp fabric (NCF) composites under the combined shear and tension loading, biaxial bias extension tests with three tensile stress levels (TSLs) and four shear stress levels (SSLs) were conducted. The shear stiffness was calculated by three metho...

The inclusion of micro bubbles often exists in polyimide films (PI) during the liquid molding process, which can largely affect the mechanical performance. However, there lacks an effective method to quantify the bubble content. Herein, an obvious tension variation of a pre-stressed polyimide film is observed firstly in a vacuum test. This phenomen...

Comprised of composite fabric envelopes, airship structures offers an alternate approach for space payload platforms which are widely employed in earth observation, communication relay and meteorology forecast. As the key material of the airship structure, the mechanical behavior of airship envelopes have been extensively studied. With major resear...

PV-ETFE cushion roof combines transparent ETFE films and flexible photovoltaics, making it possible to harvest both electricity and heat from solar energy simultaneously. However, high temperature caused by solar radiation remarkably affects the mechanical behaviors of ETFE foils and converting efficiency of PV due to their thermal sensitivity. To...

The utilization of membrane structures in space engineering has attracted considerable attention in recent decades due to ultra-light weight characteristics. The measurement and calibration of dynamic performance on ground is challenging due to air effects and equipment limitation. In this paper, a novel vacuum-level vibration-testing device is dev...

Epoxy-based shape-memory polymer (ESMP), belonging to viscoelastic thermosets, exhibits strong temperature-dependent relaxation property caused by the glass transition process. Thoroughly experimental investigation and accurate numerical prediction are indispensable to be performed in the structures that demand for high precise structural controls....

As a typical fluorine-based copolymer with excellent chemical, thermal, electrical and physical properties, ETFE (ethylene tetrafluoroethylene) is usually produced into thin films as an essential building and construction material especially for constructing the permanent membrane structures in civil engineering. This paper is thus aimed to investi...

Membrane materials with the excellent thermal, optical, electrical and chemical properties have attracted significant attention in numerous research fields recently. However, while being used to construct the membrane structures, the mechanical behaviors of membrane materials are more foundational than the other properties in evaluating the structu...

The pretensioned rectangular membrane is a basic structural component that is widely used in various spacecraft, and requires experimental ground verification before being launched into orbit. However, the dynamic calibration of the membrane is a considerable challenge, because the dynamic response is sensitive to the air resistance effect. A grid...

Accurate and concise constitutive model of biaxial tensile behavior is urgently needed for the analysis of complex membrane structure engineering. A new constitutive model is developed to describe the tensile behaviors of coated fabrics from pre-tension to breaking. The shrinkage curves is employed for the first time and stress-ratio dependence coe...

Inflatable membrane structures with the advantages of light weight, large span, long duration and aesthetical appearance have gained considerable attentions from buildings, super-pressure balloons, airships and deployable antennas. This paper presents a novel computational method for in-situ finite element modeling of inflatable membrane structures...

Ethylene tetrafluoroethylene (ETFE) cushion structures with excellent building aesthetics and reasonable structural behavior can be utilized as roofs and facades of large-span building structures. The form and force of such structures interact due to structural flexibility and complexity. The determination of a suitable form needs form-finding and...

Membrane materials have been widely used in the fields of building structures, super-pressure balloons, stratosphere airships and space deployable antennas. Among the material properties, long-term creep of membranes is a very essential factor in influencing the structural safety. This paper thus presents the simultaneous uniaxial creep testing of...

As the most frequently used material in stratospheric airship, the mechanical properties of envelope fabrics that are significant for the structural analysis have attracted widespread attention. Biaxial cyclic tensile load with eleven stress ratios were applied to estimate tensile properties of envelope fabrics. Based on the stress-strain curves of...

Single-ply weave-reinforced composites (SWRC) with asymmetric large textile unit cells are increasingly used in thin-walled aerospace structures because of the high specific stiffness than the plain weave-reinforced composites. The microstructural heterogeneity makes SWRC possess different tensile, flexural, shear and torsional mechanical propertie...

This paper describes a self-developed MATLAB program for achieving complex deformation properties and accurate elastic parameters of woven fabrics. Using this program, the response surface analyses of deformation and elastic parameters were conducted to reveal the variation and evolution in stiffness, Poisson’s ratio, and orthotropy of the laminate...

Force finding of cable–strut structures is to identify self-equilibrated pre-stress states for structures with given shape, which is a crucial step in the structural design of flexible structures since pre-stresses significantly affect their mechanical behaviors. Utilizing symmetry properties of structures is generally considered as a practical way...

A stratospheric airship (SSA) is a cost-effective platform for telecommunications and science missions in near space 20 km above the Earth's surface. However, an accurate model of the structural behavior of the large envelope of a SSA composed of a series of identical gores welded together has not been developed to date owing to the complex mechani...

Given their irreplaceable advantages such as high strength-to-weight ratio, composite fabrics have been widely applied and studied. However, due to the limitation of specimen design and test procedure, integral biaxial constitutive relationships and valid failure criteria of composite fabrics were unavailable while desirable. In this study, typical...

Inflatable membrane structures have gained considerable popularity in recent years owing to the advantages of light weight, beautiful surface and durability. This paper concerns the dynamic geometrical shape in-situ measurement and structural analysis of inflatable membrane structures using a low-cost three-camera system. The measurement system was...

Tensile tests of seven bias angles with a 15° increment with respect to the warp direction are conducted on a typical coated bi-axial warp knitted fabric (BWKF). By utilizing the Digital Image Correlation technique, the experimental results are processed, and detailed responses of strain contours and Poisson’s ratios are determined for some specifi...

As two typical kinds of architectural coated fabrics, PVDF coated polyester fabrics and PTFE coated glass-fiber fabrics have been prevalently used in tensile structures. Shear behaviors of architectural coated fabric is generally regarded as an unneglectable factor when analyzing and simulating mechanical response of tensile structures. This paper...

In this study, the multicyclic biaxial bias extension test using cruciform specimens with 45°-oriented fibers was carried on an advanced biaxial tensile tester, and three different shear loading histories (SLHs) were utilized to estimate shear properties of polyvinylidene fluoride (PVDF)-coated fabrics. The distribution of shear strain in the area...

Single-ply weave-reinforced shape memory polymer composites (SpWR_SMPCs) are promising materials for deployable space structures because they have high deformability, stiffness and strength and exhibit variable mechanical properties at different external temperatures. Thus, understanding their sensitivity to temperature has been a significant conce...

In order to reveal the viscoelastic mechanism and conduct simulation of SM (shape memory) effect, the stress and strain evolutions and fixity ratio equation were derived from the generalized Maxwell model with time temperature superposition principle. Fixity ratio equation shows that the shape fixity ratio can be lifted by raising the ratio of hold...

It is undeniable that full-strain range characteristics of Poisson’s ratios on the behaviors of a fabric composite are crucial. However, there have been relatively few papers devoted to this subject. In this study, tensile tests of seven bias angles with a 15° increment are conducted on a typical coated biaxial warp-knitted fabric (BWKF) to estimat...

The nonlinear vibration properties of a coilable mast will decide the prestress of cable and the vibration control of spacecraft. The vibration analysis of the coilable mast was figured in the prestress range which had been derived by geometrical exact analysis and buckling analysis. For small amplitude vibrations, the geometric nonlinearity caused...

Inflatable membrane structure employs flexible membranes as main constructive materials, as well as pressurized gas in the membrane envelope aiming to provide the bearing capacity and structural integrity. Therefore, the internal pressure control and load simulation method are very significant to estimate the structural behavior of inflatable membr...

With the favorable space retaining advantage, airship structures provide a cost-effective approach for the high altitude payload platform. While composite envelopes, the key material for an airship capsule, were extensively studied, the mechanical behavior of weld seams remained unclear. As weld seams may be the authentic controlling factor for the...

Formulations and numerical simulations of shape memory process are essential issues in mechanical characterizations of shape memory polymers (SMPs). In this study, tensile stress and strain in the typical four-step thermal shape memory process are formulated basing on a Neo-Hookean hyper-viscoelastic constitutive equation that could consider the ti...

To investigate the finite strain mechanical behavior of SMPs (shape memory polymers), a finite strain viscoelastic model was derived from the classical viscoelastic model in which the elastic and viscous mechanical response were formulated with Neo-Hookean hyperelastic model and Prony series respectively, and parameters fitting equations were deriv...

As a cost-effective high-altitude platform, stratospheric airships have attracted widespread research interest. A number of studies focused on the mechanical performance of the airship envelope, which is the key system in the construction of the whole airship structure. However, few researchers have addressed the strength correlation between the st...

Thin weave reinforced composites are promising aerospace materials because of their advantages of high deformability, stiffness and strength. However, their tensile, compressive, shear and flexural mechanical properties typically behave differently due to the heterogeneous layout of the reinforcements. In this paper, a recently developed single-ply...

This paper deals with the fracture failure analysis on plain woven laminated fabrics used in stratospheric airship structures. A series of uniaxial tensile and central slit tearing tests were carefully conducted on bias specimens, and the corresponding tensile and tearing properties, including failure mechanisms and material strengths, of a laminat...

The unfolding mechanical behaviours of coilable space mast are deeply influenced by the properties in coiling process. Whether the coiling process can be conducted successfully or not depends on the stiffness ratio of the longeron and triangular batten, which is most important in engineering design. The non-hinge continuous longeron and triangular...

A comprehensive experimental study of the laminated fabric URETEK3216LV subjected to mono-uniaxial, uniaxial cyclic and biaxial cyclic loading was performed to expose the detailed mechanical behaviors and determine proper elastic parameters for the laminated fabrics under specific stress states. The elastic modulus-strain curves and elastic paramet...

Since the high altitude airship provides an economical platform for earth observation, telecommunication and space exploration, its structural envelope materials attracted wide research interests. Although the uniaxial strength was studied extensively, it cannot properly characterize the real strength of the envelope due to the normal biaxial tensi...

For a structure with given shape, to acquire feasible pre-stress states without changing its predefined shape is the main purpose of force finding as a crucial step in structural designs, since mechanical behaviors of cable-strut structures are highly sensitive to their pre-tensioning levels. One of practical ways to initial force designs is double...

Based on our prior study on uniaxial tearing tests, the influences of slit parameters, off-axis angles, and loading speeds on the tearing behaviors and strengths were discussed further. Results show that the tearing behaviors and strengths of the studied material are affected by above factors significantly, and typical tearing stress-displacement c...

The use of enhanced plain woven fabrics for aerospace engineering needs essential and accurate mechanical parameters for analyzing structural behavior and performing numerical simulations. The uniaxial tensile tests are direct and effective approaches to investigate these mechanical properties. This study focused on uniaxial monotonic and cyclic me...

The use of fluorinated ethylene propylene (FEP) foils as engineering materials for aerospace, solar thermal collector and neutrino detector applications has attracted considerable attention in recent decades. Mechanical properties are indispensable for analyzing corresponding structural behavior to meet the demands of safety and serviceability. In...

Creep properties of ethylene tetrafluoroethylene (ETFE) foils are indispensable for evaluating serviceability limit state, especially under high temperature and high stress. This paper concerned temperature and stress effects on creep properties of ETFE foils with experimental and theoretical studies. Experimental results showed that dimensionless...

Ethylene tetrafluoroethylene (ETFE) cushion structures with the capacities of aesthetical appearance, excellent insulation and high strength-to-weight ratio have attracted considerable attention in recent years. Conventional ETFE cushion structures need fundamental form finding and cutting patterns, resulting in complex analysis and necessary strai...

ETFE (ethylene tetrafluoroethylene) cushion integrated flexible photovoltaics (PV) is an extension of building integrated photovoltaics into membrane structures, which could be near zero-energy, sustainable and environmental-friendly buildings. This paper focused on a two-layer ETFE cushion integrated flexible photovoltaics with experimental study...

ETFE (ethylene-tetrafluoroethylene) cushion structures have been widely used as building roofs and façades in recent years. However, mechanical behaviors and structural performance of ETFE cushions in cold regions have not been well-understood, which limits its applications in such regions. This paper is thus aimed to study the behaviors of ETFE cu...

In order to carry out the further analysis of an inflatable membrane structure during the phase of normal operation, a finite element modelling method for inflatable membrane structures is presented based on photogrammetry. The proposed method is divided into four steps. Firstly, the three-dimensional coordinates of the target points pasted on the...

Buildings with ethylene tetrafluoroethylene (ETFE) foils have attracted considerable attention due to excellent material properties, good architectural performance and structural behavior in comparison with glass structures. Generally, analyzing overall performance of ETFE structures is an interdisciplinary subject in terms of active control, envir...

A series of biaxial tensile tests were conducted on high performance laminated fabrics Uretek3216LV in order to reveal the response characteristics of laminated fabrics in the plane stress space, and the stress-strain data at nine stress ratios were obtained. Using the MATLAB program, the response surfaces of tensile strains and elastic parameters...

Uniaxial extension tests of ethylene-tetra-fluoro-ethylene (ETFE) foil specimens with a thickness of 250 μm were conducted by using eight kinds of extension speeds, where the extremely slow speed is 1 mm/min, and the extremely fast speed is 500 mm/min. The stress-strain curves, the yield stress and the Young's modulus at different extension speed w...

This paper presents an in-situ method to determine strain and stress distributions of inflatable membrane structure using photogrammetry. Firstly, dynamic shape of the target inflatable membrane structure can be obtained following photogrammetric procedure. Secondly, based on 3D coordinates of measured points before and after deformations, strain d...

The amorphous silicon photovoltaic (a-Si PV) cells are widely used for electricity generation from solar energy. When the a-Si PV cells are integrated into building roofs, such as ETFE (ethylene-tetrafouoroethylene) cushions, the temperature characteristics are indispensible for evaluating the thermal performances of a-Si PV and its constructions....

In order to analyze modal characteristics of complex shape pneumatic empennages, based on the potential flow theory and pre-stressed rigid model, the analysis method to calculate the air added mass of a triangle element was proposed by using the equivalent area parameter of a triangle element. And a numerical procedure based on Abaqus UEL was devel...

Two design methods of ETFE cushion were presented which are the three-dimensional patterning based on zero-stress state and the flat-patterning based on nonlinearity of ETFE material. The state definitions and mechanical models were defined for the two methods, respectively. Experiments and numerical simulations were performed to obtain the shapes,...

ETFE (ethylene tetrafluoroethylene) cushion roof integrated photovoltaic (PV–ETFE cushion roof) is an environment-friendly retrofit with advantages of cushion structures and capacity of utilizing solar energy. PV temperature due to photothermal effect could noticeably influence mechanical properties of ETFE foils and temperature boundary conditions...

An equilateral triangle ethylene-tetrafluoroethylene (ETFE) cushion model with a side length of 2.5 m was developed based on the design method of flat-patterning. The experimental model was performed with a form-developing test, which was controlled and measured combining automatic pressure control, photogrammetry and laser sensor. The whole proces...

The inflatable membrane structure has been widely used in the fields of civil building, industrial building, airship, super pressure balloon and spacecraft. It is important to measure the stress distribution of the inflatable membrane structure because it influences the safety of the structural design. This paper presents an innovative methodology...

This paper reports the central slit tearing behaviors of laminated fabrics for airships from experimental investigation and analytical models. First, central slit tearing behaviors of laminated fabrics with different tear lengths were tested to obtain tearing stress-displacement curves and damage morphology. Then, an analytical model was establishe...

ETFE (ethylene tetrafluoroethylene) cushion roof integrated amorphous silicon photovoltaic (PV-ETFE cushion roof) is attractive as this roof could provide electricity for maintaining the shape of the ETFE cushion and make the building to be zero-energy. One of the essential factors for this cushion roof is the temperature which affects the system t...

ETFE cushion structure has been widely used as building roof and façade in lots kinds of civil buildings due to its advantages that mainly include transparent, lightweight, durability. There are mainly two design methods to determine the form of ETFE cushion. According to the model used for the analysis process of cutting, the two forming design me...

The indeterminacy evaluation is an effective method for system identification; it can predict the mechanical behaviors of flexible structures in the primary design. However, the conventional indeterminacy evaluation based solely on geometry and topology has neglected the influence of material properties on mechanical behavior and the contribution o...

The influence of air on pre-stressed membrane struture was revealed in order to give an anlysis method for modal behavior test and calibration of membrane structure. First, pre-stress of membrane structure was introduced by appling initial stress directly and adding temperature load, respectively, and then their effects on the modal behavior were a...

In order to investigate the temperature of amorphous silicon photovoltaic panel (a-Si PV) under sunny and cloudy conditions, a thermal model was developed based on the total energy balance on the control volume. In the differential equation, the corresponding short wave radiation, long wave radiation, convection and generated power were determined,...

Uniaxial cyclic tensile tests on six groups of ethylene-tetrafluoroethylene(ETFE) foil samples of 250 μm thick were conducted. After analyzing the stress-strain curves based on a newly-developed MATLAB program, values of cyclic elastic modulus, yield stress, ratcheting strains and hysteresis loop area were obtained. Furthermore, the equations relat...

This study concerns the uniaxial tensile mechanical properties and model parameters determination of ethylene tetrafluoroethylene (ETFE) foils used in structural engineering for membrane structures such as roofs and claddings. On one hand, a series of uniaxial tensile tests under a wide range of temperatures and constant loading speeds were conduct...

A PV-ETFE mock-up and a corresponding measurement system were developed for the ethylene tetra fluoro ethylene (ETFE) cushion architecture integrated photovoltaic panels (PV). The mock-up was mainly composed of flexible amorphous silicon photovoltaic panels and a three-layer ETFE cushion. Under low solar irradiance in winter, seven on-site tests we...