Simultaneous Measurement of the Orthogonal Components of Thermal Diffusivity in PVC Sheet

1999 ◽  
Vol 122 (1) ◽  
pp. 27-32 ◽  
Author(s):  
D. J. Doss ◽  
N. T. Wright
Keyword(s):  
Thermal Diffusivity ◽  
Three Dimensional ◽  
Estimation Algorithm ◽  
Flash Method ◽  
Plane Component ◽  
Out Of Plane ◽  
Parameter Estimation Algorithm ◽  
Orthogonal Components ◽  
Bottom Face ◽  
Made In

An extension of the flash method is described that measures simultaneously the three orthogonal components of thermal diffusivity in specimens of moderate thermal diffusivity. Only part of the top face of the specimen is illuminated and the temperature histories are recorded at three points on the bottom face. A Marquardt parameter estimation algorithm coupled with a finite difference model of the diffusion equation analyzes these temperature histories to determine the components of thermal diffusivity. Illustrative measurements in stainless steel, glass, and PVC demonstrate that accurate three-dimensional thermal diffusivity measurements can be made in this way. The in-plane components of thermal diffusivity of as-supplied PVC sheet are shown to be about 20 percent greater than the out-of-plane component. This anisotropy appears to be due to the manufacturing process and exemplifies the need for such measurements. [S0022-1481(00)70101-0]

scholarly journals Ambiguity Analysis and Resolution for Phase-Based 3D Source Localization under Given UCA

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Zhen Liu ◽  
Xin Chen ◽  
Zhenhua Wei ◽  
Tianpeng Liu ◽  
Linlin Li ◽  
...  
Keyword(s):  
Ambiguity Resolution ◽  
Elevation Angle ◽  
Three Dimensional ◽  
Estimation Algorithm ◽  
Cosine Function ◽  
Phase Ambiguity ◽  
Key Factors ◽  
Half Wavelength ◽  
Parameter Estimation Algorithm ◽  
Resolution Algorithm

Under uniform circular array, by employing some algebraic schemes to exploit the phase information of receiving data and further estimate the source’s three-dimensional (3D) parameters (azimuth angle, elevation angle, and range), a series of novel phase-based algorithms with low computational complexity have been proposed recently. However, when the array diameter is larger than source’s half-wavelength, these algorithms would suffer from phase ambiguity problem. Even so, there always exist certain positions, where the source’s parameters can still be determined with nonambiguity. Therefore, this paper first investigates the zone of ambiguity-free source 3D localization using phase-based algorithms. For the ambiguous zone, a novel ambiguity resolution algorithm named ambiguity traversing and cosine matching (ATCM) is presented. In ATCM, the phase differences of centrosymmetric sensors under different ambiguities are utilized to match a cosine function with sensor number-varying, and the source’s unambiguous rough angles can be derived from amplitude and initial phase of the cosine function. Then, the unambiguous angles are employed to resolve the phase ambiguity of the phase-based 3D parameter estimation algorithm, and the source’s range as well as more precise angles can be achieved. Theoretical analyses and numerical examples show that, apart from array diameter and source’s frequency, the sensor number and spacing of employed sensors are two key factors determining the unambiguous zone. Moreover, simulation results demonstrate the effectiveness and satisfactory performance of our proposed ambiguity resolution algorithm.

Thermal Characterization of Carbon-Carbon Composites

2011 ◽  
Author(s):  
Messiha Saad ◽  
Darryl Baker ◽  
Rhys Reaves
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Carbon Composite ◽  
Flash Method ◽  
Carbon Composites ◽  
Energy Storage Devices ◽  
Graphitized Carbon

Thermal properties of materials such as specific heat, thermal diffusivity, and thermal conductivity are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells and solar cells. Thermal conductivity plays a critical role in the performance of materials in high temperature applications. Thermal conductivity is the property that determines the working temperature levels of the material, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this research is to develop thermal properties data base for carbon-carbon and graphitized carbon-carbon composite materials. The carbon-carbon composites tested were produced by the Resin Transfer Molding (RTM) process using T300 2-D carbon fabric and Primaset PT-30 cyanate ester. The graphitized carbon-carbon composite was heat treated to 2500°C. The flash method was used to measure the thermal diffusivity of the materials; this method is based on America Society for Testing and Materials, ASTM E1461 standard. In addition, the differential scanning calorimeter was used in accordance with the ASTM E1269 standard to determine the specific heat. The thermal conductivity was determined using the measured values of their thermal diffusivity, specific heat, and the density of the materials.

Magnetic out-of-plane component in MnAs/GaAs(001)

2003 ◽  
Vol 83 (14) ◽  
pp. 2850-2852 ◽  
Author(s):  
A. Ney ◽  
T. Hesjedal ◽  
C. Pampuch ◽  
J. Mohanty ◽  
A. K. Das ◽  
...  
Keyword(s):  
Plane Component ◽  
Out Of Plane

Numerical and experimental investigation for enhancing the energy absorption capacity of the novel three-dimensional printed sandwich structures

2021 ◽  
pp. 146442072199749
Author(s):  
H Geramizadeh ◽  
S Dariushi ◽  
S Jedari Salami
Keyword(s):  
Energy Absorption ◽  
Sandwich Structures ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
The Novel ◽  
Energy Absorption Capacity ◽  
Fused Deposition ◽  
Honeycomb Sandwich ◽  
Out Of Plane ◽  
Vertical Walls

The current study focuses on designing the optimal three-dimensional printed sandwich structures. The main goal is to improve the energy absorption capacity of the out-of-plane honeycomb sandwich beam. The novel Beta VI and Alpha VI were designed in order to achieve this aim. In the Beta VI, the connecting curves (splines) were used instead of the four diagonal walls, while the two vertical walls remained unchanged. The Alpha VI is a step forward on the Beta VI, which was promoted by filleting all angles among the vertical walls, created arcs, and face sheets. The two offered sandwich structures have not hitherto been provided in the literature. All models were designed and simulated by the CATIA and ABAQUS, respectively. The three-dimensional printer fabricated the samples by fused deposition modeling technique. The material properties were determined under tensile, compression, and three-point bending tests. The results are carried out by two methods based on experimental tests and finite element analyses that confirmed each other. The achievements provide novel insights into the determination of the adequate number of unit cells and demonstrate the energy absorption capacity of the Beta VI and Alpha VI are 23.7% and 53.9%, respectively, higher than the out-of-plane honeycomb sandwich structures.

scholarly journals In-Process Measurement of Three-Dimensional Deformations Based on Speckle Photography

2021 ◽  
Vol 11 (11) ◽  
pp. 4981
Author(s):  
Andreas Tausendfreund ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Evaluation Method ◽  
Process Analysis ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Machining Process ◽  
Image Correlation ◽  
Speckle Photography ◽  
Process Measurement ◽  
Out Of Plane ◽  
Plane Deformations

In the concept of the process signature, the relationship between a material load and the modification remaining in the workpiece is used to better understand and optimize manufacturing processes. The basic prerequisite for this is to be able to measure the loads occurring during the machining process in the form of mechanical deformations. Speckle photography is suitable for this in-process measurement task and is already used in a variety of ways for in-plane deformation measurements. The shortcoming of this fast and robust measurement technique based on image correlation techniques is that out-of-plane deformations in the direction of the measurement system cannot be detected and increases the measurement error of in-plane deformations. In this paper, we investigate a method that infers local out-of-plane motions of the workpiece surface from the decorrelation of speckle patterns and is thus able to reconstruct three-dimensional deformation fields. The implementation of the evaluation method enables a fast reconstruction of 3D deformation fields, so that the in-process capability remains given. First measurements in a deep rolling process show that dynamic deformations underneath the die can be captured and demonstrate the suitability of the speckle method for manufacturing process analysis.

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