The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Mission Applications Study

Adhesive joints serve under thermal loads as well as structural loads. The different thermo-mechanical properties of the adhesive and adherend materials cause incompatible thermal strains along the adhesive and adherend interfaces. Consequently, nonuniform thermal stress distributions are observed in the adhesive joints. In case the adhesive joints are constrained, these thermal stresses become more evident even for a uniform temperature distribution. In practice the adhesive joints interact with fluids (air) with different temperature and velocity and experience conductive and convective heat transfers. The variable thermal boundary conditions introduce a new non-linearity in addition to the geometrical and material non-linearities which are observed in adhesive joints. The transient temperature distributions can be obtained by solving the energy equation under the thermal boundary conditions. The corresponding thermal strain and stress distributions can be calculated using the transient temperature distributions. The large displacement and rotations occurring in adhesive joints require the implementation of the small strain-large displacement theory to the elastic stress analysis. This study introduces a simple method for calculating the heat transfer coefficients between the fluid and adhesive joints and explains the implementation of the finite element method to the thermal analysis and the geometrical nonlinear stress analysis. The thermal stresses in the metal-metal adhesive single lap, tubular, metal-metal and composite tee joints were analysed for the variable thermal and specified structural boundary conditions. The variable thermal boundary conditions cause non-uniform temperature distributions through the adhesive lap joints; consequently, non-uniform thermal strain and stress distributions occur. The adherend and adhesive regions in the neighborhood of the adhesive-adherend interfaces were subjected to high stress concentrations.

Static ice pressure due to thermal expansion is a key parameter for the design of hydraulic structures in cold regions. Thermal ice stress is affected by various factors, including thermal conditions of ice sheet (ice temperature, temperature rise rate, etc.), ice sheet constraint conditions, ice sheet thickness, etc., which leads to uncertainties in the estimation of thermal ice stress. To investigate the spatial and temporal distribution of thermal ice stress, a prototype observation was conducted to No.6 pond of Qinghuahu lake in Daqing City, Heilongjiang Province, and the ice temperature and thermal stress were fully analyzed. The analysis results indicate that ice temperature mainly depends on the fluctuation of air temperature, and that the ice temperature of each layer fluctuates more gently with time than air temperature. With the increase of ice depth, the fluctuation range of ice temperature decreases, and ice temperature increases. The surface ice temperature is well linearly related with air temperature by the change rate between 0.38 and 0.56, and the influence of air temperature on ice temperature is quite obvious within 30 cm, and ice temperature below 30 cm presents a linear distribution along depth. Based on Bergdahl's rheological constitutive relation of static ice, a mathematical model of thermal ice stress is proposed. The undetermined parameter in the model is determined by regression combining with measured data, and its values obviously depend on measuring positions. The calculated values of ice stress agree well with the measured ones. From station 1 to station 4, the overall thermal ice stresses increase. The stress is non-monotonically distributed along ice depth, i.e., thermal stress in surface ice is slightly smaller, reaches a maximum at the depth of 10~30 cm, and then gradually declines with depth. Moreover, thermal ice stresses only appear on the upper part of the ice within 0.7 m.

Advanced control of large-scale wind turbines: Structural load reduction and lifetime control

On non-linear thermal stresses in an adhesively bonded single lap joint

Thermal fatigue and cracking behaviors of asphalt mixtures under different temperature variations

Flat slab is reinforced concrete plate construction without beam. Without using beam, the obtainable profit is to minimize concrete volume, height/floor, and structural load. Other profits are simpler and economic reinforcement, scaffolding, and formwork. In this study, structural redesign of RSGM UGM Prof. Soedomo Yogyakarta building was made by using flat slab method. The objective of this study was to find structural dimension of floor and roof plates as well as reinforcement of the RSGM UGM Prof. Soedomo Building using structural system of flat slab, dimension of structural column and drop panel as well as reinforcement of the RSGM UGM Prof. Soedomo Building using structural system of flat slab. This method was to redesign using flat slab method complying with the standard of SNI 2847-2013 and software ETABS 2017. The results of analysis and calculation of structural dimension using flat slab method showed floor plate thickness of 170 mm; roof plate thickness, 120 mm; drop panel thickness, 270 mm with drop panel width of 2000 mm in direction x and 1500 mm in direction y, as well as use of column dimension of 500 mm x 500 mm. The analysis using software ETABS 2016 showed building structure in period (T) of 1.07 seconds.Keywords: RSGM UGM Prof. Soedomo Building, Drop Panel, Flat slab.

Turbine blisk low cycle fatigue (LCF) is affected by various factors such as heat load, structural load, operation parameters and material parameters; it seriously influences the reliability and performance of the blisk and aeroengine. To study the influence of thermal-structural coupling on the reliability of blisk LCF life, the generalized regression extreme neural network (GRENN) method was proposed by integrating the basic thoughts of generalized regression neural network (GRNN) and the extreme response surface method (ERSM). The mathematical model of the developed GRENN method was first established in respect of the LCF life model and the ERSM model. The method and procedure for reliability and sensitivity analysis based on the GRENN model were discussed. Next, the reliability and sensitivity analyses of blisk LCF life were performed utilizing the GRENN method under a thermal-structural interaction by regarding the randomness of gas temperature, rotation speed, material parameters, LCF performance parameters and the minimum fatigue life point of the objective of study. The analytical results reveal that the reliability degree was 0.99848 and the fatigue life is 9419 cycles for blisk LCF life when the allowable value is 6000 cycles so that the blisk has some life margin relative to 4500 cycles in the deterministic analysis. In comparison with ERSM, the computing time and precision of the proposed GRENN under 10,000 simulations is 1.311 s and 99.95%. This is improved by 15.18% in computational efficiency and 1.39% in accuracy, respectively. Moreover, high efficiency and high precision of the developed GRENN become more obvious with the increasing number of simulations. In light of the sensitivity analysis, the fatigue ductility index and temperature are the key factors of determining blisk LCF life because their effect probabilities reach 41% and 26%, respectively. Material density, rotor speed, the fatigue ductility coefficient, the fatigue strength coefficient and the fatigue ductility index are also significant parameters for LCF life. Poisson’s ratio and elastic modulus of materials have little effect. The efforts of this paper validate the feasibility and validity of GRENN in the reliability analysis of blisk LCF life and give the influence degrees of various random parameters on blisk LCF life, which are promising to provide useful insights for the probabilistic optimization of turbine blisk LCF life.

The revolution towards digitalization has changed most aspects of people's lives. Along with technological developments, new innovations are also needed that can make various activities more practical, efficient and comfortable, especially in the financial sector. New innovations are also needed, especially in the financial sector. The Covid-19 pandemic has limited all direct contact activities and has had an impact on changing people's habits towards the payment system from cash to non-cash. Technology Acceptance Model (TAM) is a research model conducted to analyze the factors that influence the use of information technology. This study aims to analyze the effect of perceived benefits, perceived convenience, perceived risk on interest in reusing Ovo e-wallet in this study using a quantitative research approach. The design of this study used survey measurements using a data collection tool using a questionnaire through a Likert scale. Based on the results of research that has been conducted online using Google Forms, questionnaires were distributed to respondents who have used the ovo e-wallet application at least 2 times or more than the last 6 months, then respondents are domiciled in DKI Jakarta and surrounding areas. Respondents who were collected in this study were 101 respondents, then the data was processed using the multiple linear regression method. The results of data analysis carried out with the help of SPSS software version 28.0.0.0 Based on the results of data analysis to measure the validity test in this study, the variables of perceived benefits, perceived convenience, perceived risk and interest in reusing OVO e-wallet were declared valid with significant values and reliability tests. by using Cronbach's Alpha coefficient that the four variables are declared reliable with a significance value. Then the classical assumption test is carried out which includes the Normality Test, Multicollinearity Test, and Heteroscedasticity Test. Based on the results of the analysis, it is known that the perceived benefits variable, perceived convenience simultaneously and partially have a positive and significant effect on the interest in reusing the ovo e-wallet, while the risk perception variable has no effect on interest. in reusing ovo e-wallet. Determination (R2) based on the value can be seen from the analysis of the effect of perceived benefits, perceived comfort, perceived risk of interest in reusing ovo e-wallet with a value of 0.524. The dependent variable to determine the results of the statistical test showed that the hypothesis was accepted, namely perceived benefits, perceived convenience, interest in reuse, while the hypothesis was rejected, namely perceived risk because it had no significant effect. Then from the analysis results obtained that the perceived benefit variable is the dominant variable..

In order to control the thermal stress of forming process,based on "element birth and death" technology of finite element method,a numerical simulation of three-dimensional temperature field and stress field during multi-track and multi-layer laser metal deposition shaping(LMDS) process is developed with ANSYS parametric design language(APDL).The dynamic variances of temperature field and stress field of forming process are calculated with the energy compensation of interaction between molten pool-powder and laser-powder.The temperature field,temperature gradient,thermal stress field and distribution of residual stress are obtained.The results indicate that although the nodes on different layers are activated at different time,their temperature variations are similar.The temperature gradients of samples are larger near the molten pool area and mainly along z-direction.The transient thermal stress has concentrated in large temperature gradient area,which is in accordance with thermal stress forming theory.Through analyzing the residual stress of the as-formed samples in different directions,distribution rule of residual stress is achieved from temperature gradient perspective.And formation mechanism of residual stress is verified with an indirect way.Finally,it's verified that the analysis results are consistent with actual situation by the experiments with same process parameters.

When drilling and completing a deep water well, the cemented top is usually several hundred meters below the mudline because of the multi-layer technical casing technology, so quite a portion of completion fluid would be entrapped in the technical casing annulus between wellhead sealing washer and the top of cement mantle. And when being in production, the temperature field of immediate vicinity of wellbore would be redistributed by thermal fluid. At the same time, the high temperature of trapped completion fluid would trigger high thermal stress, and it is proved to be a great threat to the safety of deepwater wellbore. In this paper, we build a heat transfer model for trapped wellbore under the condition of different production outputs and fluid properties, and it is based on the structural features of high temperature and high pressure well in YQ deepwater oil field of South China Sea. Following this modelling, trapped pressure of casing was predicted and a numerical simulation of temperature field in trapped wellbore was conducted in ANSYS. Based on the results of modelling and numerical simulation, we designed a suit of casing tool which can eliminate the fatal influence caused by thermal stress of trapped pressure accompanying with high temperature. The application of this anti-thermal-stress tools showed that it is effective in protecting casing, and it also reduces the risk of casing deformation accident such as deformation caused by trapped thermal stress and wellhead sealing damages.

Energy-saving operation strategy of air conditioning system in tea brick fermentation room under different outdoor meteorological parameters

Time-domain analysis of nonlinear motion responses and structural loads on ships and offshore structures: development of WISH programs

Modeling the fire-induced spalling in concrete structures incorporating hydro-thermo-mechanical stresses

The Cargo-X UAV aircraft is a UAV aircraft designed to carry medicines, packages and blood bags in areas that require fast and efficient handling. One of the important components of the Cargo-X UAV aircraft is the wing, so the strength of the wing structure must be seriously considered to ensure safety during flight under unexpected conditions. The purpose of this study was to analyze the wing structure of the UAV Cargo-X aircraft made of sandwich composite material to determine the level of safety of the wing structure. The loading of the wing structure uses the load due to the lift. The wing structure modeling uses CATIA software, while the analysis uses PATRAN/NASTRAN software. From the analysis results, the skin and spar wing structures are safe against loading, while the core section is not safe against loading.

Thermal stress analysis of silo in radioactive waste repository considering construction conditions