A multiscale non-orthogonal model for tensile properties of uncoated and coated F-12 aramid fabric

Coated F-12 aramid fabric can be used as the balloon envelopes material because of the high strength and light weight performance. In this paper, a multiscale non-orthogonal material model was established to capture the tensile properties of F-12 fabric with and without polyethylene terephthalate-aluminum (PET-Al) coating. Off-axial monotonic tensile tests were carried out to validate the material model. The nonlinearity and anisotropic properties of the coated and uncoated fabrics were investigated. In this model, the stress was obtained based on the equilibrium equations and yarn constitutive model in mesoscale. The mesoscale configuration was observed through optical microscope and SEM. The material orientation was aligned with the yarn directions and the stress was updated in real time. The material model was implemented by user material subroutine in ABAQUS and simulate fabric off-axial tensile test. In addition, a theory model to calculate the elastic property of the fabric was also set up using the mesoscale deformation mechanism. The simulation results were compared with the test and theory results. Results suggest that simulation results were agree well with test results. The fabrics were nearly linearity in weft direction, while the stressstrain curve exhibited obvious nonlinearity in warp direction. The tensile modulus of the fabric showed orthotropic behaviour rather than the strength. The coating can affect the strength and failure model of F-12 fabric. Yarn slip was the mostly failure model in uncoated fabric while break in coated fabric. Research in this study provides certain reference in analysis and design for balloon envelops

Numerical analysis of aeroelastic characteristics of airship envelope

Stratospheric airship has great advantages, such as long-endurance, large coverage area, low-cost and so on, these advantages make airship be an ideal stratospheric platform and become highly valued. Airship envelope is a large inflatable membrane structure. As a key component, the envelope features flexible and large displacement. There is strong coupling between envelope structure and the ambient air when airship operating in the high altitude sky. The coupling characteristics have great impact on the aerodynamic and structural performance of airship. Aiming at the aeroelastic characteristics of the envelope structure, a fluid-structure coupled computational method is presented basing on a finite element program. As an example, the envelope structure of airship is computed and the S-A turbulent model is used. The envelope drag coefficient under different attack angle is computed. The contrast between experimental results coming from reference paper and numerical results highlight the correctness of this method. With the developed computational approach, the NPL envelope is also analyzed. The changes of length to diameter ratio, max cross section location and Reynolds number are studied and the aeroelastic characteristics of flexible envelope are analyzed. These results can give some valuable information for precise forecast of the overall airship performance

Dynamics testing and simulation of inflatable deployable

The inflatable deployablemembrane antenna structures have many advantages such as small folding size, high reliability and low cost. The structure mainly consists of its center hub, thin-plate ribs, inflatable thermo-curing torus, reflected membrane and inflation control system. This paper establishes a deployable system to simulate zero-gravity based on the parabolic membrane antenna with inflatable torus and tests the deployable process. The shell-membranes finite element model of the antenna structuresis modeled to simulateof the dynamics charactersof the structure. After that the effectsof the different inflatable pressure inside its support torus, the temperature of thermos-curing on the dynamic characteristics are also discussed.Finally,the dynamic charactersof the inflatable antenna was tested on the condition of the horizontal suspension system with 12 elastic strings and the fully structural vibrational frequency were given, and the mode of vibration and damping ratio was verified to the correctness of the simulation method. These results provide the reference for the design of inflatable deployment antenna structures

Numerical simulations for gas-structure interaction in inflated deployment of folded membrane boom

AbstractIt is very important for gas-structure interaction between compressible ideal gas and elastic structure of space folded membrane booms during the inflatable deployment. In order to study this gas-structure interaction problem, Arbitrary Lagrangian-Eulerian (ALE) finite element method was employed. Gas-structure interaction equation was built based on equilibrium integration relationship, and solved by operator split method. In addition, numerical analysis of V-shape folded membrane booms inflated by gas was given, the variation of inner pressure as well as deployment velocities of inflatable boom at different stage were simulated. Moreover, these results are consistent with the experiment of the same boom, which shows that both ALE method and operator split method are feasible and reliable methods to study gas-structure interaction problem

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

A multiscale non-orthogonal model for tensile properties of uncoated and coated F-12 aramid fabric

Coated F-12 aramid fabric can be used as the balloon envelopes material because of the high strength and light weight performance. In this paper, a multiscale non-orthogonal material model was established to capture the tensile properties of F-12 fabric with and without polyethylene terephthalate-aluminum (PET-Al) coating. Off-axial monotonic tensile tests were carried out to validate the material model. The nonlinearity and anisotropic properties of the coated and uncoated fabrics were investigated. In this model, the stress was obtained based on the equilibrium equations and yarn constitutive model in mesoscale. The mesoscale configuration was observed through optical microscope and SEM. The material orientation was aligned with the yarn directions and the stress was updated in real time. The material model was implemented by user material subroutine in ABAQUS and simulate fabric off-axial tensile test. In addition, a theory model to calculate the elastic property of the fabric was also set up using the mesoscale deformation mechanism. The simulation results were compared with the test and theory results. Results suggest that simulation results were agree well with test results. The fabrics were nearly linearity in weft direction, while the stressstrain curve exhibited obvious nonlinearity in warp direction. The tensile modulus of the fabric showed orthotropic behaviour rather than the strength. The coating can affect the strength and failure model of F-12 fabric. Yarn slip was the mostly failure model in uncoated fabric while break in coated fabric. Research in this study provides certain reference in analysis and design for balloon envelops

Numerical analysis of aeroelastic characteristics of airship envelope

Stratospheric airship has great advantages, such as long-endurance, large coverage area, low-cost and so on, these advantages make airship be an ideal stratospheric platform and become highly valued. Airship envelope is a large inflatable membrane structure. As a key component, the envelope features flexible and large displacement. There is strong coupling between envelope structure and the ambient air when airship operating in the high altitude sky. The coupling characteristics have great impact on the aerodynamic and structural performance of airship. Aiming at the aeroelastic characteristics of the envelope structure, a fluid-structure coupled computational method is presented basing on a finite element program. As an example, the envelope structure of airship is computed and the S-A turbulent model is used. The envelope drag coefficient under different attack angle is computed. The contrast between experimental results coming from reference paper and numerical results highlight the correctness of this method. With the developed computational approach, the NPL envelope is also analyzed. The changes of length to diameter ratio, max cross section location and Reynolds number are studied and the aeroelastic characteristics of flexible envelope are analyzed. These results can give some valuable information for precise forecast of the overall airship performance