Pseudo-beam method for compressive buckling characteristics analysis of space inflatable load-carrying structures

This paper extends Le van＇s work to the case of nonlinear problem and the complicated configuration. The wrinkling stress distribution and the pressure effects are also included in our analysis. Pseudo-beam method is presented based on the inflatable beam theory to model the inflatable structures as a set of inflatable beam elements with a prestressed state. In this method, the discretized nonlinear equations are given based upon the virtual work principle with a 3-node Timoshenko＇s beam model. Finite element simulation is performed by using a 3-node BEAM189 element incorporating ANSYS nonlinear program. The pressure effect is equivalent included in our method by modifying beam element cross-section parameters related to pressure. A benchmark example, the bending case of an inflatable cantilever beam, is performed to verify the accuracy of our proposed method. The comparisons reveal that the numerical results obtained with our method are close to open published analytical and membrane finite element results. The method is then used to evaluate the whole buckling and the loadcarrying characteristics of an inflatable support frame subjected to a compression force. The wrinkling stress and region characteristics are also shown in the end. This method gives better convergence characteristics, and requires much less computation time. It is very effective to deal with the whole load-carrying ability analytical problems for large scale inflatable structures with complex configuration.

Numerical analysis of stress distribution in the upper arm tissues under an inflatable cuff：Implications for noninvasive blood pressure measurement

An inflatable cuff wrapped around the upper arm is widely used in noninvasive blood pressure measurement.However, the mechanical interaction between cuff and arm tissues, a factor that potentially affects the accuracy of noninvasive blood pressure measurement, remains rarely addressed. In the present study, finite element（FE） models were constructed to quantify intra-arm stresses generated by cuff compression, aiming to provide some theoretical evidence for identifying factors of importance for blood pressure measurement or explaining clinical observations. Obtained results showed that the simulated tissue stresses were highly sensitive to the distribution of cuff pressure on the arm surface and the contact condition between muscle and bone. In contrast, the magnitude of cuff pressure and small variations in elastic properties of arm soft tissues had little influence on the efficiency of pressure transmission in arm tissues. In particular, it was found that a thickened subcutaneous fat layer in obese subjects significantly reduced the effective pressure transmitted to the brachial artery, which may explain why blood pressure overestimation occurs more frequently in obese subjects in noninvasive blood pressure measurement.

Self-Repairing Membranes for Inflatable Structures Inspired by a Rapid Wound Sealing Process of Climbing Plants

A new self-repairing membrane for inflatable light weight structures such as rubber boats or Tensairity constructions is presented. Inspired by rapid self-sealing processes in plants, a thin soft cellular polyurethane foam coating is applied on the inside of a fabric substrate, which closes the fissure if the membrane is punctured with a spike. Experimental tests are carried out with a purpose built setup by measuring the air mass flow through a leak in a damaged membrane sample. It is shown that the weight per unit area of the self-repairing foam as well as the curing of the two component PU-foam under an overpressure influence the repair efficiency. Curing the foam under overpressure affects the relative density as well as the microstructure of the foam coatings. Maximal median repair efficiencies of 0.999 have been obtained with 0.16 g.cm 2 foam cured at 1 bar overpressure. These results suggest that the bio-inspired technique has the potential to extend the functional integrity of injured inflatable structures dramatically.

Inflatable hollow obturator prostheses for patients undergoing an extensive maxillectomy:a case report

The presence of a large palatal or maxillary defect after partial or total maxillectomy for tumor, trauma or congenital deformation poses a challenge to prosthodontists, particularly when the use of an implant cannot be considered. This case report described the use of an air valve in a hollow silicone obturator to manufacture an inflatable obturator that could be extended further into undercut area to retain itself. The inflatable obturator exhibited adequate retention, stability and border sealing, thereby improving the masticatory, pronunciation and swallowing functions of patients. It may be a suitable alternative treatment option to an implant-retained obturator.

Structural design and modal behaviors analysis of a new swept baffled inflatable wing

Inflatable wing has significant application value in the design of loitering munitions because of its advantages such as lightweight and foldability.However,due to the flexible characteristics,aeroelastic behaviors of inflatable wings such as flutter are nonnegligible in flight.By designing a certain angle between the inflatable beam and the wing span,the structural dynamic and even the aeroelastic performance of the inflatable wing can be effectively improved.Based on the analysis of the mechanical and geometric characteristics of the inflatable structure,a new inflatable wing with sweep arranged inflatable beams is proposed,and the main design variables and methods are analyzed.For purpose of investigating the aeroelastic performance of the swept baffled inflatable wing,the modal behaviors by considering the wet mode are studied.In consideration of the deficiencies of the traditional wet modal analysis method,by introducing the influence on the additional stiffness of flow field,an added massstiffness method is proposed in this paper,and the advantages are verified by ground vibration experiments.On this basis,the effects of baffles sweep angle,pressure,and boundary conditions on the modal parameters and aeroelastic performance of inflatable wing are analyzed.The results show that the aeroelastic performance of the inflatable wing can be designed by changing the baffles sweep angle,which is enlightened for the aeroelastic tailoring design on inflatable wings.

Analysis of effect of pressure on surface accuracy for inflatable antenna

Pressure is one of the important measures to control the surface accuracy of the reflector of inflatable antenna. Experiments and numerical analysis were carried out to highlight the effect of pressure on accuracy. The rapid, contactless and low-cost digital photogrammetry system （DIES） was employed to investigate the effect according to its lightweight and flexible characteristics. Measurement data show that the best pressure and the best area in this pressure can be obtained. Numerical analysis was conducted to check the measurement result. It is indicated that there is a little difference between them attributed to wrinkle. Results of analysis and experiments show that surface accuracy of the reflector can be adjusted by controlling pressure.

Deformation of wrinkled membrane inflatable structures under concentrated loads

The axisymmetric deformation of a paraboloidal membrane inflatable structure subjected to a concentrated load at its apex and a uniform internal pressure was analyzed. The wrinkle angle was obtained according to the membrane theory when wrinkles appeared and determined the wrinkle region. The wrinkled deformation was obtained based on the relaxed energy function. The effects of inflation pressure and concentrated loads on the wrinkle angle were analyzed and the deformation was obtained at the apex of structure. According to the numerical analysis, the shape of deformed meridians with wrinkles was obtained.

A simple analytical method for deflation prediction of inflatable structures

The static performance of inflatable structures has been well studied and the dynamic deployment simulation has received much attention. However, very few studies focus on its deflation behavior. Although there are several dynamic finite element algorithms that can be applied to the deflation simulation, their computation costs are expensive, especially for large scale structures. In this work, a simple method based on classic thermodynamics and the analytical relationship between air and membrane was proposed to efficiently analyze the air state variables under the condition of ventilation. Combined with failure analysis of static bearing capacity, a fast incremental analytical method was presented to predict both elastic and post wrinkling deflation process of inflatable structures. Comparisons between simplified analysis, dynamic finite element simulation, and a full-scale experimental test are presented and the suitability of this simple method for solving the air state and predicting the deflation behavior of inflatable structures is proved.

Perianesthesia emergency repair of a cut endotracheal tube’s inflatable tube:A case report

BACKGROUND During the perianesthesia period,emergency situations threatening the life and safety of patients can occur at any time.When dealing with some emergencies,occasional confusion is inevitable.CASE SUMMARY This case report describes the rare situation wherein a surgeon inadvertently detached the inflatable tube of an endotracheal tube during a tonsillectomy,and positive pressure ventilation could not be provided.While reintubation may increase the risk of respiratory tract infection and aspiration,patients with a difficult airway might die due to apnea.The best treatment method is to optimize the damaged tracheal tube junction to avoid secondary intubation and ensure patient safety.An intravenous needle and cannula were used to repair the damaged gap in the current case.Following the repair,the anesthesia machine showed no indication of low tidal volume,and there was no deflation of the endotracheal tube cuff.Subsequently,the patient was transferred to the postanesthesia recovery room,and the tracheal tube was removed with satisfactory results.CONCLUSION Using an intravenous needle to repair a break in the inflatable tube surrounding an endotracheal tube is safe and reliable.

Vacuum Preparation, Optimization of Cylinder Length and Postoperative Daily Inflation Reduces Complaints of Shortened Penile Length Following Implantation of Inflatable Penile Prosthesis

Introduction: The inflatable penile prosthesis (IPP) has been used to treat erectile dysfunction for 40 years. Loss of penile length following IPP remains the single biggest patient complaint. We describe a preoperative and postoperative patient preparation protocol to assist in setting realistic patient expectations and decreasing the complaint of reduced penile length. Materials & Methods: 750 Patients are instructed to use a vacuum erection device for 10 minutes each day for up to 2 months prior to IPP implant. After two months, maximization of cylinder length is accomplished regardless of IPP manufacturer. Cylinders are left partially inflated in the post-operative period and daily inflation for 3 months immediately upon patient tolerance. The average implanted cylinder length has increased dramatically with the preoperative vacuum usage when compared to the authors’ previous implantations and when compared to the national average of implanted cylinders obtained from one manufacturer. Results: Preoperative use of the vacuum device has allowed maximization of cylinder length. After the vacuum program, patients tend to experience less pain following implantation allowing earlier device instruction cycling and use. The average implanted cylinder length continued to increase annually for the first 5 years as the protocol evolved and seems to have remained stable for the last five years. Conclusions: Preoperative vacuum usage and postoperative capsule management has nearly eliminated patient complaints of reduced penile length. We believe this to be the result of larger size cylinders being implanted when compared to our previous implantations absent of the patient participation protocol.

Numerical Simulation for Damping-Controlled Deployment of Z-Folded Inflatable Tube

The damping-controlled deployment technology of flexible Z-folded inflatable tube is one of the key technologies of space inflatable structures.Constraint failure between couple nodes is proposed to simulate the damping-controlled deployment.And the equation of constraint failure is established.Inflation process of Z-folded tube is simulated with control volume method.Compared with uncontrolled method,it is indicated that the new method can effectively solve the disordered deployment problem of the slender Z-folded inflatable tube.By analyzing the displacement of the apical of the folded tube with different constraint forces during deployment process,the concept of effective constraint force is proposed.In the effective region of constraint force,the folded tube deploys with little retraction and fluctuation.Otherwise,The flexible folded tube would deploy disorderly or even cannot deploy.The simulation method and numerical results have a theoretical and instructive significance to the research on the space inflatable structures.

Friction characteristics of confined inflatable structures

The availability of high‐strength fabrics and progress in the development of large‐scale inflatable technology made possible the creation of temporary and quickly deployable structures for protection of underground infrastructure.Inflatable structures are relatively lightweight and portable,and can maintain the required rigidity while in operation.These benefits have prompted the development of inflatable structures for use in confined spaces,such as tunnels and large‐diameter pipes to act as barriers for containing flooding with minimal infrastructure modification.This work presents experimental results obtained from the evaluation of frictional characteristics of the fabric material that constitute the structural membrane of confined inflatable structures developed for protection of underground transportation tunnels and other large conduits.Friction tests at coupon level and slippage tests in a reduced‐scale inflatable structure were performed in order to evaluate the frictional characteristics of Vectran webbings.Tests at coupon level were performed to determine the friction coefficient for different surface types and conditions.Tests with the reduced‐scale inflatable structure contributed to the understanding of the friction characteristics at system level when subjected to different pressurization or depressurization sequences designed to induce slippage.Test results indicate that friction coefficient values at coupon level are about 29 percent higher than values derived from reduced‐scale tests.

Wrinkle Analysis of the Space Inflatable Paraboloid Antenna

The presence of wrinkles in the membrane is the main factor to induce the reflector surface inaccuracy of the space inflatable antenna.Based on the commercial finite element package ABAQUS,a numerical procedure for membrane wrinkle analysis was set up and used to analyze a space inflatable antenna which was under inner pressure to evaluate its wrinkle characteristics.First,the inner pressure effect on the reflector's wrinkle pattern was studied thoroughly.As inner pressure increases,both the number and the amplitude of the wrinkles decrease,but the total deformation of the whole reflector surface increases much.Second,the influence of the interactions between antenna's parts was investigated comprehensively.Any kind of unwanted interaction deteriorates reflector's wrinkle characteristics.The works are valuable to the development and research of the space inflatable antenna.

Design and performance of an air inflatable suit in enhancing personal thermal management

Maintaining human thermal comfort in cold indoor environments is crucial but usually involves excessive energy consumption and massive greenhouse gas emissions. Thermoregulating the human body by using advanced clothing is emerging as a promising solution to effectively and energy-efficiently achieve personal thermal management. An air inflatable suit(AirST)using a series of air chambers as the thermal insert was developed for the purpose of adjusting clothing thermal insulation and hence improving personal thermal comfort. The thermal insulation regulating performance of AirST was investigated through thermal manikin tests and wear trials. Compared with the AirST without air inflation, AirST after inflation with air had a desired effect, which could not only increase local clothing thermal insulation by a range from 4.5% to 24.8% but also alleviate cold strain and provide significantly higher local skin temperatures, mean skin temperature and mean body temperature. After inflation, AirST successfully improved the whole-, upper-and lower-body thermal sensations in a cool environment. The acceptable heating setpoint temperature by the air conditioner could be decreased while using AirST with inflation, which saved approximately 30% of building energy consumption. As the AirST without air inflation can also be worn as regular windproof clothing, this versatility saved approximately 12 kg CO_(2)e emissions in the production process.

Deployment dynamics and topology optimization of a spinning inflatable structure

Inflatable space structures may undergo the vibration of a long duration because of their features of dynamic deployment,high flexibility,and low-frequency modes.In this paper,a topology optimization methodology is proposed to reduce the vibration of a spinning inflatable structure.As the first step,a variable-length shell element is developed in the framework of arbitrary Lagrange-Euler(ALE)and absolute nodal coordinate formulation(ANCF)to accurately model the deployment dynamics of the inflatable structure.With the help of two additional material coordinates,the shell element of ALE-ANCF has the ability to describe the large deformation,large overall motion,and variable length of an inflatable structure.The nonlinear elastic forces and additional inertial forces induced by the variable length are analytically derived.In the second step,a topology optimization procedure is presented for the dynamic response of an inflatable structure through the integration of the equivalent static loads(ESL)method and the density method.The ESL sets of the variable-length inflatable structure are defined to simplify the dynamic topology optimization into a static one,while the density-based topology optimization method is used to describe the topology of the inflatable structure made of two materials and solve the static optimization problem.In order to obtain more robust optimization results,sensitivity analysis,density filter,and projection techniques are also utilized.Afterwards,a benchmark example is presented to validate the ALE-ANCF modeling scheme.The deployment dynamics and corresponding topology optimization of a spinning inflatable structure are studied to show the effectiveness of the proposed topology optimization methodology.

Inflatable Wing Design Parameter Optimization Using Orthogonal Testing and Support Vector Machines

The robust parameter design method is a traditional approach to robust experimental design that seeks to obtain the optimal combination of factors/levels. To overcome some of the defects of the inflatable wing parameter design method, this paper proposes an optimization design scheme based on orthogonal testing and support vector machines （SVMs）. Orthogonal testing design is used to estimate the appropriate initial value and variation domain of each variable to decrease the number of iterations and improve the identification accuracy and efficiency. Orthogonal tests consisting of three factors and three levels are designed to analyze the parameters of pressure, uniform applied load and the number of chambers that affect the bending response of inflatable wings. An SVM intelligent model is established and limited orthogonal test swatches are studied. Thus, the precise relationships between each parameter and product quality features, as well the signal-to-noise ratio （SNR）, can be obtained. This can guide general technological design optimization.

Inflatable Models

A physically-based model is presented for the simulation of a new type of deformable objects-inflatable objects, such as shaped balloons, which consist of pressurized air enclosed by an elastic surface. These objects have properties inherent in both 3D and 2D elastic bodies, as they demonstrate the behaviour of 3D shapes using 2D formulations. As there is no internal structure in them, their behaviour is substantially different from the behaviour of deformable solid objects. We use one of the few available models for deformable surfaces, and enhance it to include the forces of internal and external pressure. These pressure forces may also incorporate buoyancy forces, to allow objects filled with a low density gas to float in denser media. The obtained models demonstrate rich dynamic behaviour, such as bouncing, floating, deflation and inflation.

Inflatable pressure garment device for pressure therapy after chest wall keloid operation and radiotherapy

Aim: Keloids often occur on the chest wall, with high recurrence rates despite surgery and radiotherapy. Garment pressure therapy is commonly used to treat hypertrophic scars and keloids. Irregularity of the chest wall surface can inhibit the effects of the garment pressure therapy. This clinical study is to determine the effect of inflatable pressure garment in preventing keloid recurrence after keloid operation and radiotherapy. Methods: Chest wall keloid was removed and radiotherapy was administered at the surgical sites on the 1st and 7th postoperative days in 61 patients. An inflatable pressure garment device was designed and its pressure effect was confirmed by comparing it with the general pressure garment at the sites of the right and left infraclavicular area, manubrium and sternal area between breasts. The keloid patients were treated with inflatable pressure garment device 1 month after the operation. The clinical results were observed. Results: The detected pressures were 0.26 ± 0.21, 0.49 ± 0.16, 0.53 ± 0.10 and 0.91 ± 0.17 kPa at the sites of the right infraclavicular area, the manubrium area, the left infraclavicular area and sternal area between breasts with the general pressure garment. These were obvious lower (P < 0.05) than that generated with the inflatable pressure garment device of which the average pressures were 7.26 ± 0.41, 7.6 ± 0.32, 9.02 ± 0.54 and 10.31 ± 0.14 kPa at the corresponding sites.Sixty-one patients were treated with this device after keloid surgical excision and radiotherapy. Satisfactory results were observed. Conclusion: Appropriate and effective pressure can be generated with inflatable pressure garment on the chest wall. This device may be useful in preventing chest wall keloid recurrence after keloid operation and radiotherapy.

Development simulation of an inflatable membrane antenna based on extended position-based dynamics

Inflatable membrane antennas have been extensively applied in space missions;however,the simulation methods are not perfect,and many simulation methods still have many difficulties in accuracy,efficiency,and stability.Therefore,the extended position-based dynamics(XPBD)method is employed and improved for the simulation of folded inflatable structures in this paper.To overcome the problem that the original XPBD method with only geometric constraints does not contain any mechanical information and cannot reflect the mechanical characteristics of the structure,we improve the XPBD method by introducing the strain energy constraint.Due to the complicated nonlinear characteristics of the membrane structures,the results with the traditional finite element method(Abaqus)cannot converge,while the tension field theory(TFT)can,but some pretreatments are needed.Compared with them,the method in this paper is simple and has better stability to accurately predict the displacement,stress,and wrinkle region of the membrane structure.In addition,the present method is also compared with the experiment in the reference to verify the feasibility of the folded tube simulation.Finally,the present method is applied to simulate inflatable membrane antennas and analyze the deployable driving force and deployable process sequence of each component.

Novel protective penile collar following inflatable penile prosthesis placement: the “Wang Collar”

Penile rehabilitation after inflatable penile prosthesis(IPP)implantation for the treatment of erectile dysfunction includes leaving the device partially inflated so as to preserve the penile length and to maintain hemostasis.With a partially inflated device,the penis becomes more sensitive and more susceptible to unintended insults during the immediate postoperative management.The“Wang Collar,”a device intended to protect the penis in the early postoperative period,is hereby described.Three hundred and forty-eight patients had the 44Wang Collar"included as part of their post-1 PP management from August 2014 to February 2019.The protective collar,devised from a polystyrene cup with the bottom removed,is secured with a tape over the previously dressed and partially inflated penis.In order to evaluate the effectiveness of this device,we conducted surveys on the perioperative staff at three different institutions.The“Wang Collar”has been found to be beneficial in the early postoperative care of patients.Based on the answers to our questionnaire,the perioperative personnel found this device to be highly protective,especially when transporting the patient after IPP surgery,easy to work with,and almost never bothersome or irritative to the patient.We present a novel penile device after IPP placement,which we have found to improve patient satisfaction in the postoperative period.In addition,it eases the care of the patient by the perioperative staff.It is now our routine to use this device after IPP surgery.Further research is necessary to evaluate whether this device can decrease postoperative wound complications.