Photothermoelastic Investigation of Thermal Stress in Flat Plates

1963 ◽  
Vol 85 (4) ◽  
pp. 566-568 ◽  
Author(s):  
Herbert Becker ◽  
Angelo Colao
Keyword(s):  
Temperature Field ◽  
Thermal Stress ◽  
Circular Plate ◽  
Thermal Stresses ◽  
Theoretical Data ◽  
Rectangular Plates ◽  
Flat Plates ◽  
Comparison With Experiments ◽  
Better Than ◽  
Good Agreement

Predictions of thermal stresses in various shape flat plates with a parabolic temperature field applied in one direction were found to yield good agreement with photothermoelastic analysis. A theory based upon an analog was found to agree with experiments on rectangular plates better than two other methods of analysis. The analog procedure was utilized for analysis of a circular plate, to the results of which an engineering modification was applied to obtain theoretical data for comparison with experiments on a hexagonal plate with and without a central circular hole.

Thermal Stress Analysis of a Bi-Material Layered Structure

2010 ◽  
Vol 450 ◽  
pp. 161-164 ◽  
Author(s):  
Shiuh Chuan Her ◽  
Chin Hsien Lin ◽  
Shun Wen Yeh
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Thermal Stresses ◽  
Dissimilar Materials ◽  
Beam Theory ◽  
Layered Systems ◽  
Thermal Expansion Coefficients ◽  
Parametric Studies ◽  
Expansion Coefficients ◽  
Good Agreement

Thermal stress induced by the mismatch of the thermal expansion coefficients between dissimilar materials becomes an important issue in many bi-layered systems, such as composites and micro-electronic devices. It is useful to provide a simple and efficient analytical model, so that the stress level in the layers can be accurately estimated. Basing on the Bernoulli beam theory, a simple but accurate analytical formulation is proposed to evaluate the thermal stresses in a bi-material beam. The analytical results are compared with finite element results. Good agreement demonstrates that the proposed approach is able to provide an efficient way for the calculation of the thermal stresses. It is shown that thermal stresses are linear proportion to the ratio of thermal expansion coefficients between the two materials. Parametric studies reveal that thermal stresses in each layer are decreasing with the increase of thickness, and are increasing with the increase of Young’s modulus ratio between the two materials.

Comparisons between mechanical analogue and experimental measurements for thermal stresses in two dimensions

1977 ◽  
Vol 12 (1) ◽  
pp. 37-40
Author(s):  
T Sekiya ◽  
S Sumi ◽  
M Okamoto
Keyword(s):  
Temperature Field ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Thermal Stresses ◽  
Two Dimensions ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
Mechanical Analogue ◽  
Thermoelastic Problems

This paper confirms results for plane thermoelastic problems obtained by a mechanical analogue procedure. The temperature distribution is caused by heating and cooling. The distributions of thermal stress obtained for this temperature field are compared with earlier results obtained by mechanical analogue.

scholarly journals Noncontact Optical Fiber Sensor for Measuring the Refractive Index of Liquids

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
R. Selvas-Aguilar ◽  
A. Castillo-Guzman ◽  
L. Cortez-Gonzalez ◽  
D. Toral-Acosta ◽  
A. Martinez-Rios ◽  
...  
Keyword(s):  
Refractive Index ◽  
Laser Beam ◽  
Optical Fiber ◽  
Optical Fiber Sensor ◽  
Theoretical Data ◽  
Optical Power ◽  
Fiber Sensor ◽  
Liquid Sample ◽  
Better Than ◽  
Good Agreement

A noncontact optical fiber sensor for measuring the refractive index of transparent liquids is proposed. It operates by calculating the path of a focused laser beam at 635 nm that travels across the boundaries of a liquid sample. The optical power Fresnel reflections are detected and, subsequently, the refractive index is determined as the ratio between the traveled beam paths when the liquid is deposited versus a reference without the liquid sample. Additionally, a mathematical analysis of the geometrical case is included. The theoretical data from our sensor are in good agreement with the experimental results. The resolution achieved by the sensor is better than 10−3 RIU.

Plane Thermal Stress Analysis of an Orthotropic Cylinder Subjected to an Arbitrary, Transient, Asymmetric Temperature Distribution

2002 ◽  
Vol 69 (5) ◽  
pp. 632-640 ◽  
Author(s):  
K.-C. Yee ◽  
T. J. Moon
Keyword(s):  
Temperature Field ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Analytical Solution ◽  
Stress Analysis ◽  
Stress Function ◽  
Thermal Stresses ◽  
Shear Stresses ◽  
Thermal Stress Analysis ◽  
Interlaminar Shear

A closed-form, analytical solution is presented for the transient, plane thermal stress analysis of a linearly elastic, homogeneously orthotropic hollow cylinder subjected to an arbitrary temperature distribution. The thermoelastic solution, obtained by a stress function approach, can be used as the basis for the corresponding thermoviscoelastic solution for thermorheologically simple viscoelastic materials by invoking the viscoelastic Correspondence Principle. This solution can also be directly extended to the class of weakly inhomogeneously orthotropic cylinders using perturbation methods. The transient asymmetric temperature field is characterized by Fourier-Bessel eigenfunction expansions. The analytically derived stress function satisfies a linear, fourth-order inhomogeneous partial differential equation and the Cesaro integral conditions, which assure the existence of a single-valued displacement field. The corresponding thermal stresses are then computed by the stress-stress function relations. A key feature of the analytical solution is that the hoop, radial, and shear stresses, due to the transient arbitrary temperature distribution, are expressed explicitly in terms of the scalar temperature field. A polymer composite example is presented to validate the current method and to qualitatively illustrate the distribution of thermal stresses due to an asymmetric temperature distribution. Numerical results are presented for the thermally driven hoop, radial and (interlaminar) shear stresses in a hollow, hoop-wound glass/epoxy cylinder. This analysis demonstrates that potentially debilitating interlaminar shear stresses can develop in laminated composites when subjected to an even modest transient asymmetric temperature distribution. Their magnitudes depend on the severity of the spatial and temporal thermal gradients in the circumferential direction. While still relatively low compared to the hoop stress, the shear stress may cause thermal failure due to the typically low interlaminar shear strengths of laminated composite materials.

Thermal Stresses in Rectangular Plates

1959 ◽  
Vol 10 (1) ◽  
pp. 65-78 ◽  
Author(s):  
J. S. Przemieniecki
Keyword(s):  
Thermal Stresses ◽  
Plate Thickness ◽  
Normal Modes ◽  
Thermoelastic Stress ◽  
Characteristic Functions ◽  
Vibration Modes ◽  
Rectangular Plates ◽  
Practical Application ◽  
Flat Plates ◽  
Modes Of Vibration

SummaryThe characteristic functions for beam vibration modes are used to derive an approximate solution for the calculation of thermal stresses in rectangular isotropic flat plates subjected to arbitrary temperature distributions in the plane of the plate and constant temperatures through the plate thickness. The thermal stresses are obtained in the form of generalised Fourier expansions in terms of the characteristic functions, and their derivatives, representing normal modes of vibration of a clamped-clamped beam. Since these functions have recently been tabulated, the practical application of this new method to the thermoelastic stress analysis of plates presents no difficulty.

Coupled Thermal-Structural Finite Element Simulation of Ti-6Al-4V Alloy during Electrical Discharge Machining

2010 ◽  
Vol 135 ◽  
pp. 435-440
Author(s):  
Yan Wang ◽  
Feng Gao
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Thermal Stress ◽  
Electrical Discharge ◽  
Thermal Stresses ◽  
Electrical Discharge Machining ◽  
Theoretical Models ◽  
Micro Cracks ◽  
Element Simulation ◽  
Thermal Stress Field

Theoretical models of temperature and thermal stress for Ti-6Al-4V during electrical discharge machining (EDM) process are established. Based on finite element method, the temperature field of EDM Ti-6Al-4V alloy is simulated firstly with the aid of ANSYS, the results can be used to predict the width and depth of the spark crater. The simulated results show that there is a high temperature distribution at the spark point while the zone is quite small. The thermal stress field is estimated using the results of the temperature field as input. Surrounding the spark crater, the thermal stresses are concentrated, where may cause micro-cracks.

scholarly journals Multi-way differential power divider with microstrip output interfaces

2020 ◽  
Vol 71 (4) ◽  
pp. 274-280
Author(s):  
Cheng-Guang Sun ◽  
Jia-Lin Li ◽  
Baidenger Agyekum Twumasi
Keyword(s):  
Characteristic Impedance ◽  
Theoretical Data ◽  
Power Divider ◽  
Center Frequency ◽  
Impedance Bandwidth ◽  
Power Dividers ◽  
Quarter Wavelength ◽  
Insertion Losses ◽  
Better Than ◽  
Good Agreement

AbstractThe design and implementation of planar multi-way differential power dividers remain a challenge in terms of the compactness and especially, for the achievable characteristic impedance of the quarter-wavelength transformer when considering large number of outputs. In this work, the double-sided parallel stripline is recommended to realize such a power divider with out-of-phase outputs, and explicit design methods are provided. The proposed multi-way power divider was developed without the use of lump elements on a single substrate. For system applications, a prototype operating at 41.6 MHz with 12 pairs of out-of-phase outputs that utilize the microstrip line as the output interfaces was fabricated and examined. At the center frequency of 41.6MHz, the developed prototype measured insertion losses akin to 14.3 dB as compared with the theoretical data of 13.8 dB. The attainable impedance bandwidth ranges from 10 MHz to 80 MHz under a magnitude imbalance of ±0.3 dB. The isolations of the adjacent outputs are about 13.1 dB as compared with the theoretical values of 14.428 dB, and are better than 34 dB for more distant ones. Parameter measurements are in good agreement with the numerical predications, thus demonstrating the realization of the proposed multi-way power divider.

scholarly journals A balanced-to-balanced directional coupler based on branch-slotline coupled structure

Frequenz ◽  
2020 ◽  
Vol 74 (11-12) ◽  
pp. 427-433
Author(s):  
Yaxin Liu ◽  
Feng Wei ◽  
Xiaowei Shi ◽  
Cao Zeng
Keyword(s):  
Directional Coupler ◽  
Return Loss ◽  
Design Method ◽  
Differential Mode ◽  
Arbitrary Power ◽  
Measurement Results ◽  
Transition Structures ◽  
Coupled Structures ◽  
Better Than ◽  
Good Agreement

AbstractIn this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.

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