Prediction of the temperature of a drill in drilling lunar rock simulant in a vacuum

In this article, the temperature of a sampling drill in drilling lunar rock simulant in a high-vacuum environment was studied. The thermal problem was viewed as a 1-D transient heat transfer problem in a semi-infinite object. The simplified drill was modeled using heat conduction differential equation and a fast numerical calculation method is proposed on this basis, with time and the drill discretized. The model was modified to consider the effects of radiation, drill bit configuration, and non-constant heat source. A thermal analysis was conducted using ANSYS Workbench to determine the value of the equivalent correction coefficient proposed in this paper. Using fiber Bragg grating temperature measurement method, drilling experiments were conducted in a vacuum, and the results were compared to the model. The agreement between model and experiment was very good.

A novel piezoelectric dynamometer based on double-sensor for thermal compensation

A piezoelectric dynamometer can produce thermal forces because of temperature fluctuations, thus affecting measurement precision. To investigate the influence of the thermal force on the dynamometer, this article proposes a hypothesis of decreasing the conduction power and establishes the function of a thermal force over time in an ordinary dynamometer based on the heat conduction differential equation. A novel double-sensor thermal compensation dynamometer is designed, with static calibration in constant temperature and force/heat coupling experiments, to solve the problem of the thermal force. The experimental results indicate that the nonlinearity and repeatability of the double-sensor thermal compensation dynamometer are less than 1% full scale (FS) of the static calibration at a constant temperature; in the force/heat coupling experiments, at a heating rate of 0.4 ℃/s to 110 ℃ with a loading force of 500 N, the maximal output deviation is less than 1.06% (FS), realizing the unidirectional thermal force compensation of the structure. The double-sensor thermal compensation dynamometer can be utilized in sharp temperature fluctuations environment, like rocket engine forces measurement.

Sequentially Coupled Thermal-Mechanical Analysis of the Brake Disc Used in Air Disc Brake

The basic theory involved in the coupled thermal mechanical analysis is presented briefly. Base on the contact theory, friction heat generation theory and heat transfer theory, the heat distribution ratio between the disc and brake pad is determined, a 3D transient heat conduction differential equation and corresponding boundary conditions are established. Finally, according to the analysis requirement, the business analysis software ABAQUS is chosen as sequentially coupled thermal mechanical analysis solver. In order to know the temperature of discs friction surface during the cycle braking and continuous braking processes, a sequentially coupled thermal mechanical analysis model of the disc is established according to the energy dissipation theory. The temperature field and stress field of the disc during emergency braking, repeat braking and continuous braking processes are carried out based on this model.

Analysis of Temperature Field of the Tunnel Surrounding Rock in Cold Regions

Freeze-thaw disaster is an outstanding problem of geotechnical engineering in cold regions. The temperature field of tunnel surrounding rock in Qilian mountain Osaka hill was calculated according to the transient heat conduction differential equation, meanwhile the freezing conditions of tunnel surrounding rock was forecasted and analyzed after its opening. The study shows that the freeze-thaw environment has a great influence on the temperature distribution of surrounding rock. The tunnel wall and near the mouth of the cave area are more susceptible to the influence of the open ground temperature and air convection, thus the temperature changes violently , but the temperature distribution in surrounding rock tends to be dynamic stable equilibrium as time goes on. The research results can provide a reference for tunnel design and construction in cold regions.

Thermal Deformation in a Static Pressure Dry Gas Seal

Based on the basic principles of heat transfer, the two-dimensional stable state cylindrical coordinate solid heat conduction differential equation having no inner heat source is established. Use the ANSYS software to establish the temperature field finite element analysis model of rotating and stationary rings and carry on the solution to the temperature field. The temperature distributing rules of rotating and stationary rings are obtained at the same time. According to thermo-elastic deformation theory, numerical analysis method and separation method are applied to resolve and analyze thermal-structural coupling deformation of rotating and stationary rings.

Influence of Reinforcement on Temperature and Stress of Hollow Pier

This paper put circular hollow bridge pier under cold wave as an example. Based on solid heat conduction principle, we selected its border and initialized condition according with actual circumstance. Combining solid heat conduction differential equation and generalized hooke’s law which takes temperature stress into account, we have calculated the temperature and stress of concrete piers with different reinforcement ratio by ANSYS finite element software. These results indicate that the longitudinal bars and horizontal ring stirrups in concrete circular hollow pier under cold wave will increase its outer surface temperature tensile stress. Namely the reinforcements in concrete circular hollow pier not only do not prevent its outer surface cracks under the action of cold wave, but will also promote the surface cracks to produce faster. Therein, the contribution of horizontal ring stirrups to the surface cracks is greater than the longitudinal bars.

Concise BEM for State Heat Conduction of FGMs

The thermal conductivity problem of functionally graded plate is studied under different temperature fields by a new concise BEM in this paper. At first, we convert the heat conduction differential equation of functionally graded materials (FGMs) to a homogeneous material thermal conductivity equation by using variable substitution, then the Galerkin boundary integral equation is reduced to be a system of linear equations. Finally we arrive at an internal temperature of objects, and plot the distribution graphics and effects of material parameters on temperature distribution. It proves that the new concise BEM is very effective.

Study of Transverse Section Temperature Distribution in Underground Coal Gasification

In order for current laboratory studies of strata performances under high temperature to be applied in Underground Coal Gasification (UCG) technology, the temperature scope (range) of UCG must be studied. Based on the heat conduction differential equation, this paper simulates the transverse section temperature distribution of UCG in the multi-physics coupling field. It demonstrates that the strata properties at a range of two meters are affected by high temperature, and the influence on sandstone is more obvious than that of coal. The temperature curves show a trend of linear to nonlinear as time goes. This paper presents the precedent of using multi-field coupling calculation to simulate UCG.

Research on the Relationship between Temperature and Dimension of Large-Scale Forgings in Manufacturing Process

In order to achieve online monitoring about hot-state dimension of large-scale forgings, a new monitoring method has been developed in this paper. The large-scale barrel-type forgings heat conduction differential equation is deduced on the basis of the heat transfer. The functional form of heat conduction equation for large-scale forgings is established. Then the relationship between temperature and dimension is solved according to the variational principle. So the dimension of the large-scale forgings is monitored by combining the relationship between temperature and dimension. The temperature is measured by sensor. As a result, the online monitoring about hot-state dimension of large-scale forgings is achieved.