Modal Analysis of Wing Considering Transient Thermal Effects

2013 ◽  
Vol 444-445 ◽  
pp. 1400-1406 ◽  
Author(s):  
Hao Liu ◽  
Xia Sheng Sun ◽  
Xiao Dong Li
Keyword(s):  
Modal Analysis ◽  
Thermal Environment ◽  
Temperature Gradients ◽  
Large Temperature ◽  
Aerodynamic Heating ◽  
Transient Temperature ◽  
Transient Temperature Field ◽  
Vehicle Structure ◽  
Wing Structure ◽  
Transient Thermal

The severe aerodynamic heating on the surface of modern hypersonic flight vehicle, that can bring high temperature and large temperature gradients in the structure of the vehicle, will be a challenge for the vehicles design and multidisciplinary optimization. The transient thermal environment consists of high temperature and large temperature gradients will generate two important problems related to vehicle structure, namely: 1) the material property, such as elastic modulus, will be degraded at elevated temperature, and 2) the non-uniform thermal stress cased by large temperature gradients will change the stiffness distribution of wing structure, which can make the modal frequencies and shapes of structure changed remarkably. Firstly, the theory and methodology of structure modal analysis in transient thermal environment is outlined. Subsequently, the transient temperature field of structure considering aerodynamic heating is obtained by employing computational technology of aerodynamic heating/structure heat transfer coupling program. Finally, the modal frequencies and shapes of vehicle structure under transient temperature field is calculated based on finite element method (FEM). Based on the analysis and investigation of the simulation results, the influence of the transient thermal environment on structure modal frequency and shape is determined. Furthermore, the investigation of wing structure modal analysis considering aerodynamic heating is an important basis of aerothermoelastic simulation.

Study on the Influence of Temperature and Stress Field to PCB’s Modal

2012 ◽  
Vol 271-272 ◽  
pp. 1441-1445
Author(s):  
Qin Luo ◽  
Su Juan Zhang ◽  
Xiao Zhang
Keyword(s):  
Temperature Field ◽  
Stress Field ◽  
Modal Analysis ◽  
Heat Flux Density ◽  
Heat Dissipation ◽  
Transient Temperature ◽  
Electronic Products ◽  
Transient Stress ◽  
Transient Temperature Field ◽  
Pcb Design

With the increasing integration of electronic products, the heat flux density is increasing. Research on the heat dissipation of the PCB attracts more attention. Temperature field of the electronic products always changes a lot, usually leading to a transient stress field in the PCB. Due to the transient temperature field and transient stress field, the PCB’s modal changed. In this paper, the temperature field and the stress field are obtained to explain the reason of the change. The influence on PCB’s modal caused by the temperature field and the stress field are analyzed, on the basis of PCB’s thermal modal analysis, which provide a reference for the PCB design and modal analysis in the future.

The Understanding of Thermomechanical Analysis of a Thermal Protection System

2013 ◽  
Vol 753-755 ◽  
pp. 1467-1476
Author(s):  
Xiao Bo Peng
Keyword(s):  
Thermal Stresses ◽  
Thermal Protection ◽  
Space Shuttle ◽  
Space Vehicle ◽  
Temperature Limit ◽  
Thermal Protection System ◽  
Protection System ◽  
Aerodynamic Heating ◽  
Transient Temperature ◽  
Vehicle Structure

Nowadays, reusable launch vehicle (RLV) has become a research focus of the transportation system between ground and space and the space weapon system. RLV plays an important role in controlling the cost of space transportation and performing the orbital mission. Since RLV would suffer from the aerodynamic heating inevitably during reentry, the thermal protection system (TPS) is designed to prevent too much heat transmitting to the vehicle structure and maintain the vehicle structure below a specified temperature limit. Several studies were performed to develop an understanding of not only the thermal and structural analysis of ceramic tile thermal protection system on the space shuttle but also the controlling factors of TPS. The TPS is subjected to the reentry heating and pressure profile of the Access to Space vehicle, and the transient temperature distribution and the resultant thermal stresses in the system are computed. Comparisons between various studies based on different assumptions were examined. By comparing these results with more realistic ones, the differences are evaluated. Results suggest that the TPS analysis must be based on reasonable and realistic parameters. Thus, engineers have to keep in mind that all parameters should be chosen very carefully to achieve results that close to practical ones.

Behavior of a Tapered Hub Flange With a Bolted Flat Cover in Transient Temperature Field

1996 ◽  
Vol 118 (1) ◽  
pp. 115-120 ◽  
Author(s):  
T. Sawa ◽  
T. Hirose ◽  
Y. Nakagomi
Keyword(s):  
Thermal Condition ◽  
Thermal Loading ◽  
Transient Temperature ◽  
Strain Gages ◽  
Bolted Connection ◽  
Transient Temperature Field ◽  
Bolt Stress ◽  
Transient Thermal ◽  
Flat Cover ◽  
Steel Bolts

An experimental and analytical study was made on a bolted connection subjected to thermal loading. The connection consists of an aluminum alloy tapered hub flange and a flat cover, including a gasket fastened by steel bolts and nuts. Temperature distribution in the connection was measured with thermocouples, and the axial bolt force, the maximum bolt stress, and the hub stress were measured by strain gages under a thermal condition that theinner surface of the flanges was heated and the outer surfaces of the flanges and the cover were held at room temperature. Finite difference analysis was made to obtain the temperature distributions in the connection due to a transient thermal condition. This paper demonstrates the method for obtaining an increment in axial bolt force and the maximum bolt stress. In all cases, the analytical results were fairly consistent with the experimental results.

Behavior of Pipe Flange Connection in Transient Temperature Field

1993 ◽  
Vol 115 (2) ◽  
pp. 142-146 ◽  
Author(s):  
T. Sawa ◽  
T. Hirose ◽  
H. Kumano
Keyword(s):  
Thermal Conduction ◽  
Room Temperature ◽  
Maximum Stress ◽  
Transient Temperature ◽  
Strain Gages ◽  
Bolted Connection ◽  
Transient Temperature Field ◽  
The Difference ◽  
Transient Thermal ◽  
Steel Bolts

The behavior of a bolted connection, using several aluminum alloy pipe flanges with steel bolts and nuts, was examined under the condition of thermal conduction. Using the finite difference method, temperature distributions in the connection subjected to transient thermal conduction were analyzed. A method for obtaining an increment in axial bolt force and the maximum stress produced in the bolts was demonstrated. In the experiments, the temperature distribution in the connection was measured by use of thermocouples. In addition, both the increment and the maximum stress due to the difference in coefficients of linear expansion as well as the stress produced in the hub were measured by strain gages when the inner circumference of the pipe flanges was subjected to thermal conduction and the outer circumference was kept at room temperature. The analytical results were fairly consistent with the experimental ones.

Thermal State of an Aircraft Aerofoil in a High-Velocity Air Flow

2021 ◽  
pp. 4-24
Author(s):  
Az.A. Aliev ◽  
A.S. Burkov ◽  
V.A. Tovstonog ◽  
V.I. Tomak ◽  
D.A. Yagodnikov
Keyword(s):  
High Velocity ◽  
Zirconium Oxide ◽  
Air Flow ◽  
Temperature Gradients ◽  
Supersonic Combustion ◽  
Design Solution ◽  
Large Temperature ◽  
Aerodynamic Heating ◽  
Correct Operation ◽  
Temperature State

One of the features of high-velocity atmospheric aircraft is the presence of thin aerofoils with edges characterised by a small blunt radius, subjected to high-temperature aerodynamic heating at temperatures of up to 2000 -- 2500 °C. In order to ensure correct operation of both the power plant producing thrust in such vehicles, assumed to be a supersonic combustion ramjet, and respective aerodynamic controls, the components subjected to high-velocity air flows must retain their geometric stability. A way to ensure their performance is to use methods and means of thermal protection, as well as materials that are resistant to high temperatures in an oxidising atmosphere, while one of the promising trends is employing refractory oxide materials such as oxides of aluminium, zirconium and hafnium. Since this class of materials has low thermal conductivity, large temperature gradients develop in the vicinity of the surface being heated, resulting in temperature stresses, all of which designers should take into account. We analysed the temperature state in a model of an acute zirconium oxide wedge featuring a small blunt radius, subjected to a high-velocity air flow. To reduce the edge temperature and temperature gradients, we propose a design solution implemented as a thermally conductive core lined with a thin layer of zirconium oxide. We consider using aluminium oxide and hafnium boride as core materials

Influences of New Electrical Material on Transient Heat Transfer in IMCCR

2011 ◽  
Vol 291-294 ◽  
pp. 1669-1673
Author(s):  
Jun Ci Cao ◽  
Wei Li Li ◽  
Xiao Chen Zhang ◽  
Yi Huang Zhang
Keyword(s):  
Induction Motor ◽  
Motor Performance ◽  
Heat Diffusion ◽  
Transient Temperature ◽  
Thermal Coupling ◽  
Analysis Method ◽  
Transient Temperature Field ◽  
Transient Thermal ◽  
Cage Rotor ◽  
Material Permeability

A new kind of alloy (conductor for electric and magnetic), is proposed in this paper, which applied in induction motor rotor bars, and a kind of induction motor with compound cage rotor(IMCCR) is obtained. By using the electromagnetic-thermal coupling analysis method, the transient temperature field of an IMCCR is numerically analyzed, and the transient thermal process of motor operating with blocked rotor for 10s and then stopped for 10min natural cooling is calculated. The heat diffusion of stator equivalent windings and the double-directions heat transmission processes in stator are analyzed. Based on which, the influences of rotor material permeability and conductivity on motor performance are studied. Comparing with the normal nonmagnetic material, the alloy could improve motor performance significantly while ensure motor thermal performance, which indicates the wide application of such alloy in electrical machines.

Study on Vibration Characteristics of the Vehicles Wing Structure in High Temperature Environment

2013 ◽  
Vol 482 ◽  
pp. 200-206
Author(s):  
Da Fang Wu ◽  
Lin Zhu ◽  
Yue Wu Wang ◽  
Shou Gen Zhao ◽  
Ying Pu
Keyword(s):  
High Temperature ◽  
High Speed ◽  
Thermal Environment ◽  
Vibration Characteristics ◽  
Thermal Vibration ◽  
Aerodynamic Heating ◽  
Thermal Stress Field ◽  
Wing Structures ◽  
Wing Structure ◽  
Cruise Missiles

During the flight of the long-range cruise missiles, aerodynamic heating can cause the temperature of the wing structure, fairing, missile body and other components to rise rapidly, along with serious structural vibrations. The thermal environment generated by aerodynamic heating significantly changes the mechanical properties of the materials and structure, including the elastic modulus, stiffness, and so on. The complex flight maneuver process will also produce high-temperature gradients, which affect the thermal stress field. Both of these impacts significantly affect the characteristics of the missile structures natural vibration. In this paper, thermal vibration joint testing was performed on two different wing structures of a high-speed missile under a thermal environment, and the vibration characteristics of the wing structure (e.g., the natural frequency) at various temperatures were obtained. The experimental results can provide a reliable basis for the safety design of the wing structure of missiles under high-speed thermal vibration conditions.

Transient Temperature During the Vaporization of Liquid on a Pulsed Laser-Heated Solid Surface

1996 ◽  
Vol 118 (3) ◽  
pp. 702-708 ◽  
Author(s):  
H. K. Park ◽  
X. Zhang ◽  
C. P. Grigoropoulos ◽  
C. C. Poon ◽  
A. C. Tam
Keyword(s):  
Thin Film ◽  
Solid Surface ◽  
Elevated Temperatures ◽  
Bubble Nucleation ◽  
Transient Temperature ◽  
Specular Reflectance ◽  
Transient Temperature Field ◽  
Excimer Laser Pulse ◽  
Nanosecond Time Resolution ◽  
Laser Heated

The thermodynamics of the rapid vaporization of a liquid on a solid surface heated by an excimer laser pulse is studied experimentally. The transient temperature field is measured by monitoring the photothermal reflectance of an embedded thin film in nanosecond time resolution. The transient reflectivity is calibrated by considering a temperature gradient across the sample based on the static measurements of the thin film optical properties at elevated temperatures. The dynamics of bubble nucleation, growth, and collapse is detected by probing the optical specular reflectance. The metastability behavior of the liquid and the criterion for the onset of liquid–vapor phase transition in nanosecond time scale are obtained quantitatively for the first time.

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