scholarly journals The effect of model material properties on thermal imaging measurements

2021 ◽  
Vol 2057 (1) ◽  
pp. 012095
Author(s):  
A I Kutepova ◽  
P A Polivanov ◽  
A A Sidorenko
Keyword(s):  
Temperature Distribution ◽  
Material Properties ◽  
Thermal Imaging ◽  
Conjugate Problem ◽  
Model Material ◽  
Main Flow ◽  
Homogeneous Material ◽  
Solid Model ◽  
Temperature Distributions ◽  
Boundary Layer Interaction

Abstract The temperature distributions arising on the surface of the solid model are investigated. A flow with a shock wave and laminar boundary layer interaction is considered as the main flow. Calculations of the conjugate problem are performed based on RANS approach. The investigated cases correspond to homogeneous material of the solid model and the model consisting of two materials with different thermal conductivity. In this study, the model designs are found to obtain a temperature distribution suitable for thermal imaging measurements. In addition, in the calculations, the effect of forced heating of the model wall on the temperature distribution is investigated.

On the Application of Tensor Product Solids in Heterogeneous Solid Modeling

1998 ◽  
Author(s):  
Anne Marsan ◽  
Debasish Dutta
Keyword(s):  
Tensor Product ◽  
Process Planning ◽  
Material Properties ◽  
Model Material ◽  
Layered Manufacturing ◽  
Solid Model ◽  
Heterogeneous Objects ◽  
Solid Models ◽  
Multiple Materials ◽  
Heterogeneous Solid

Abstract With the development of layered manufacturing (LM) technologies, engineers are now able to build objects which are composed of multiple materials and/or have varying material properties throughout. These so called heterogeneous objects can be described by heterogeneous solid models, which contain information about the boundaries of the object, as well as material properties. In this paper we show how tensor product solids, which are the 3D extension of tensor product surfaces, can be used to model material properties within the framework of a heterogeneous solid model. We then show how a heterogeneous solid model which makes use of tensor product solids can be used in reverse engineering and process planning for LM.

scholarly journals Temperature Measurement Technologies and Their Application in the Research of Fuel Cells

2003 ◽  
Author(s):  
Mao Hai Wang ◽  
Hang Guo ◽  
Chong Fang Ma ◽  
Fang Ye ◽  
Jian Yu ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Temperature Distribution ◽  
Thermal Imaging ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Temperature Fields ◽  
Infrared Thermal Imaging ◽  
Exterior Surface ◽  
Temperature Distributions ◽  
Exchange Membrane

Fuel cells have attracted extensive attention throughout the world in recent years for their high efficiency and high environmental compatibility. Temperature plays a key role in achieving high performance of fuel cells because it deeply influences the activity of catalyst, dehydration of solid polymer membrane, mass transfer and heat management of fuel cells. The temperature distribution has close relationship with current density distribution and lifetime of fuel cells because the uniformity of temperature distribution is a quite important problem for fuel cells. In this paper, a review of temperature measurement technologies that can be used to measure temperature distribution of fuel cells was presented. The measurement of cathode exterior surface temperature fields of a hydrogen proton exchange membrane fuel cell under various operational conditions was conducted by using the technology of infrared thermal imaging. The proton exchange membrane fuel cell structure was designed for uniformity of input heat. A NEC TH5102 thermo tracer was applied to measure the cathode exterior surface temperature distributions of the cell with 5cm2 active area. The experimental results showed that the infrared thermal imaging is an effective method to measure the exterior temperature fields of the PEMFC. The cathode temperature distributions of the cell varied with cell temperatures and flow rates.

Computational Problems in Orthopaedic Biomechanics

1993 ◽  
Vol 323 ◽  
Author(s):  
Dean Taylor
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Composite Structures ◽  
Complex Geometry ◽  
Active Material ◽  
Structural Response ◽  
Model Material ◽  
Homogeneous Material ◽  
Finite Element Models ◽  
Gauss Point

AbstractTotal joint replacements such as the hip and knee result in composite structures. Proper design of these devices and selection of particular devices requires understanding of the structural response of the resulting composite structure of plastic, metal, interface, and human bone. The problem is challenging because of complex geometry, non-homogeneous material properties (dense cortical bone and spongy cancellous bone), and time varying material properties (bone remodeling). Bone is a active material which responds over time to applied load, changing the density and Young's modulus.This paper addresses several computational issues. Remote sensed data such as computerized tomography scans are used to create finite element models. Nonhomogeneous material properties are represented in finite element models using shape functions. This results in a unique material property for each Gauss point. Finally, stochastic finite elements methods are used to model material variation and uncertainty. Both Monte Carlo and First Order Second Moment methods are used. These problems are particularly well suited for high-level parallelization schemes on multiple instruction multiple data machines.

Interference-Free Multi-Axis NC Machining of Cylindrical Cam Using Enveloping Element

2009 ◽  
Vol 419-420 ◽  
pp. 333-336
Author(s):  
Jeng Nan Lee ◽  
Chih Wen Luo ◽  
Hung Shyong Chen
Keyword(s):  
Cutting Tool ◽  
Nc Machining ◽  
Model Material ◽  
Solid Model ◽  
End Mill ◽  
Generating Method ◽  
Collision Problem ◽  
Five Axis ◽  
Cutting Path ◽  
Cutting Simulations

To obtain the flexibility of choice of cutting tool and to compensate the wear of the cutting tool, this paper presents an interference-free toolpath generating method for multi-axis machining of a cylindrical cam. The notion of the proposed method is that the cutting tool is confined within the meshing element and the motion of the cutting tool follows the meshing element so that collision problem can be avoided. Based on the envelope theory, homogeneous coordinate transformation and differential geometry, the cutter location for multi-axis NC machining using cylindrical-end mill is derived and the cutting path sequences with the minimum lead in and lead out are planned. The cutting simulations with solid model are performed to verify the proposed toolpath generation method. It is also verified through the trial cut with model material on a five-axis machine tool.

Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation

2021 ◽  
Vol 21 (11) ◽  
pp. 293
Author(s):  
Shan-Xiang Wei ◽  
De-Qing Kong ◽  
Qi-Ming Wang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Radio Telescope ◽  
Thermal Imaging ◽  
Uniform Temperature ◽  
Large Radio Telescope ◽  
Uniform Temperature Distribution ◽  
Uniform Temperature Field ◽  
Main Reflector

Abstract The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector, which will dramatically reduce the aperture efficiency of a radio telescope. To study the non-uniform temperature field of the main reflector of a large radio telescope, numerical calculations including thermal environment factors, the coefficients on convection and radiation, and the shadow boundary of the main reflector are first discussed. In addition, the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element analysis. The simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven, and the maximum of the root mean square temperature is 12.3°C. To verify the simulation results, an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear day. At the same time, some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup structure. It has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement, and the cosine similarity between the simulation and the measurement is above 90%. Despite the inevitable thermal imaging errors caused by large viewing angles, the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large extent. The temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar radiation. It is credible to calculate the temperature field of the main reflector through the finite element method. This work can provide valuable references for studying the thermal deformation and the surface accuracy of the main reflector of a large radio telescope.

scholarly journals Is Thermal Imaging a Useful Predictor of the Healing Status of Diabetes-Related Foot Ulcers? A Pilot Study

2018 ◽  
Vol 13 (3) ◽  
pp. 561-567
Author(s):  
Behzad Aliahmad ◽  
Aye Nyein Tint ◽  
Sridhar Poosapadi Arjunan ◽  
Priya Rani ◽  
Dinesh Kant Kumar ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Pilot Study ◽  
Thermal Imaging ◽  
Color Image ◽  
Foot Ulcer ◽  
Clinic Visit ◽  
Color Images ◽  
Thermal Images ◽  
Reduction In Area

Introduction: In clinical practice, both area and temperature of the ulcer have been shown to be effective in tracking the healing status of diabetes-related foot ulcer (DRFU). However, traditionally, the area of the DRFU is measured regardless of the temperature distribution. The current prospective, observational study used thermal imaging, as a more accurate tool, to measure both the area and the temperature of DRFU. We aimed to predict healing of DRFU using thermal imaging within the first 4 weeks of ulceration. Method: A pilot study was conducted where thermal and color images of 26 neuropathic DRFUs (11 healing vs 15 nonhealing) from individuals with type 1 or 2 diabetes were taken at the initial clinic visit (baseline), at week 2, and at week 4. The thermal images were segmented into isothermal patches to identify the wound boundary and area corresponding to temperature distribution. Five parameters were obtained: temperature of the wound bed, area of the isothermal patch of the wound bed, area of isothermal patch of periwound, number of isolated isothermal patches of the wound region, and physical wound bed area from color image. The ulcers were also measured by experienced podiatrists over 4 consecutive weeks and used as the healing reference. Results: For healing cases, the ratio of the area of the wound bed to its baseline measured using thermal images was found to be significantly lower at 2 weeks compared to nonhealing cases and this corresponded with a 50% reduction in area of DRFU at 4 weeks (group rank-based nonparametric analysis of variance P = .036). In comparison, neither the planimetric area measured using color images nor the temperature of the wound bed was associated with the healing. Conclusion: This study of 26 patients demonstrates that change in the isothermal area of DRFU can predict the healing status at week 4. Thermal imaging of DRFUs has the advantage of incorporating both area and temperature allowing for early prediction of the healing of these ulcers. Further studies with greater sample sizes are required to test the significance of these results.

The Transient Temperature Distribution in a Slab Subject to Thermal Radiation

1965 ◽  
Vol 87 (1) ◽  
pp. 117-130 ◽  
Author(s):  
R. D. Zerkle ◽  
J. Edward Sunderland
Keyword(s):  
Temperature Distribution ◽  
Thermal Radiation ◽  
Radiant Heat ◽  
Analog Computer ◽  
Graphical Form ◽  
Transient Temperature ◽  
Transient Temperature Distribution ◽  
Temperature Distributions ◽  
Approximate Analytical Solutions ◽  
Wide Range

The transient, one-dimensional temperature distribution is determined for a slab, insulated on one face, and subjected to thermal radiation at the other face. The slab is initially at a uniform temperature and is assumed to be homogeneous, isotropic, and opaque; the physical properties are assumed to be independent of temperature. Transient temperature distributions for both heating and cooling situations are obtained by means of a thermal-electrical analog computer. A diode limiter circuit is used to simulate the nonlinear radiant heat flux. The transient temperature distributions are presented in a dimensionless, graphical form for a wide range of variables. Approximate analytical solutions are also given which complement and extend the solution charts over ranges of parameters not covered in the charts.

Responses of Aluminium Alloy Pistons under Mechanical and Thermal Loads

2019 ◽  
Vol 969 ◽  
pp. 231-236
Author(s):  
Chandan Kumar ◽  
Nilamber Kumar Singh
Keyword(s):  
Thermal Analysis ◽  
Combustion Engine ◽  
Topological Optimization ◽  
Solid Model ◽  
Thermal Loads ◽  
Transient Thermal Analysis ◽  
Critical Areas ◽  
Temperature Distributions ◽  
Transient Thermal ◽  
3D Solid

A comparative study of three different aluminium alloys, Al2618, Al4032 and Al6061 made internal combustion engine pistons is done on their responses under mechanical and thermal loads using finite element methods. In this study, a 3D solid model of piston is created in CATIA and the simulations of the static structural analysis, steady-state thermal analysis and transient thermal analysis are carried out in ANSYS. Stress and temperature distributions on critical areas of piston are pointed out for appropriate modification in piston design. The temperature and heat flux variations with time are presented in transient thermal analysis. Taguchi method and topological optimization are applied to optimize the process parameters and to select the appropriate material for the piston.

scholarly journals Influence of Burner Position on Temperature Distribution in Soybean Flaming

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 391 ◽  
Author(s):  
Miloš Rajković ◽  
Goran Malidža ◽  
Strahinja Stepanović ◽  
Marko Kostić ◽  
Kristina Petrović ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Dry Matter ◽  
Growth Stage ◽  
Flame Temperature ◽  
Soil Surface ◽  
High Variability ◽  
Temperature Distributions ◽  
Soybean Canopy ◽  
Soybean Plants ◽  
Surface Flame

The main objective of this study was to identify optimal burner orientation for a newly designed flame cultivator by quantifying the flame temperature distributions of cross, back, and parallel position of burners at different heights of the soybean canopy (distance from the soil surface). Flame temperatures were measured within-row for three burner orientations at seven propane doses (20–100 kg/ha) and eight different canopy heights (0–18 cm above soil surface). Soybean plants in V3 growth stage were flamed with the same doses and burner orientations, and 28 days after treatment (DAT) crop injury (0%–100%), plant height (cm), dry matter (g) and grain yield (t/ha) were assessed. All three burner orientations had high flame temperatures at lower canopy heights (<6 cm high) that gradually decreased with increasing canopy height (6–18 cm). Measured temperatures ranged from 33 to 234 ℃ for cross flaming, 29 to 269 ℃ for back flaming and 23 to 155 ℃ for parallel flaming, with high variability in temperature patterns. Back flaming generated flame temperatures above 100℃ at a lower propane dose (27 kg/ha) compared to cross and parallel flaming (40 and 50 kg/ha). For all tested parameters, parallel and cross flaming had better impact on soybeans than back flaming, but for weed control in crop rows, cross flaming is recommended.

The Design Tradeoffs of Linear Functionally Graded Piezoceramic Actuators

Aerospace ◽  
2003 ◽  
Author(s):  
Paul W. Alexander ◽  
Diann Brei
Keyword(s):  
Material Properties ◽  
High Stress ◽  
Functionally Graded ◽  
Homogeneous Material ◽  
Stress Concentrations ◽  
Practical Applications ◽  
Complex Electric Field ◽  
Design Tradeoffs ◽  
A Minor ◽  
The Cost

It is common practice to reduce the voltage level within piezoelectric actuators by utilizing multiple layers, typically bonded together. Unfortunately, this has a tendency to result in device failure due to delamination. For example, with benders the typical lifetime is 105 to 106 cycles, limiting its use in practical applications. This poses an interesting design tradeoff: the stroke is increased due to sharper gradients between material layers; however, the higher gradients lead to high stress concentrations at those interfaces. One approach to reducing these stresses is to grade the material properties through a monolithic piece of piezoceramic so that no interfaces or bonding elements exist, but this comes at the cost of stroke. This paper explores the design tradeoff inherent to monolithic functionally graded piezoelectrics. An analytical free-displacement model for a monolithic piezoceramic beam with a generic gradient is derived. Key to this is the inclusion of the complex electric field distribution which rises from the non-homogeneous material properties. This model is used along with finite element models to examine the effect of continuous linear and stepwise material gradients on the displacement performance as well as the stress levels. The study shows that using monolithic functionally graded piezocermics can significantly reduce the stresses with only a minor impact on the device stroke.

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