Thermal Behavior

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Shelly J. Schmidt - One of the best experts on this subject based on the ideXlab platform.

  • Impact of sucrose crystal composition and chemistry on its Thermal Behavior
    Journal of Food Engineering, 2017
    Co-Authors: Lei Lei Yin, Danielle L. Gray, Leonard C. Thomas, Shelly J. Schmidt
    Abstract:

    Abstract Though crystalline sucrose is an abundant and highly refined organic compound, its Thermal Behavior is complex and not fully understood. The objective of this research was to investigate the influence of the composition and chemistry of the sucrose crystal on its Thermal Behavior, especially as related to the origin of the small endothermic DSC peak observed for most cane sucrose sources, but not for beet sucrose sources, using a variety of analytical methods and techniques. Based on the evidence herein, we assert that the presence of the small endothermic DSC peak is associated with the onset of Thermal decomposition of sucrose within mother liquor occlusions, initiated by hydrolysis and mediated by the composition and chemistry of the sucrose crystal. Any factor that affects the composition and chemistry of the sucrose crystal will in turn influence its resultant Thermal Behavior. This assertion further explains the complex sucrose Thermal Behavior issues that have heretofore not been completely elucidated, including the wide variation in the literature reported melting temperature values (location of Tmonset), the variation in the number and magnitude (ΔH) of the endothermic DSC peaks obtained, and the heating rate dependency of the melting temperature.

  • Differences in the Thermal Behavior of beet and cane sucrose sources
    Journal of Food Engineering, 2017
    Co-Authors: Leonard C. Thomas, Shelly J. Schmidt
    Abstract:

    Abstract Sucrose is a major worldwide commodity, produced mainly from sugarbeet and sugarcane. Despite the nearly identical chemical composition of these sugar sources, some differences in aroma and performance in products have been reported in the literature. However, little research exploring Thermal Behavior differences was found. By employing Thermal analysis methods, this research reveals significant Thermal Behavior differences both between and within beet and cane sugars. Beet samples exhibited only one large endothermic DSC peak (Tmonset = 188.45 ± 0.43); whereas twenty-seven of the thirty-one cane samples exhibited two endothermic DSC peaks, one small peak (Tmonset = 153.62 ± 6.04) proceeded by one large peak (Tmonset = 187.33 ± 1.72). However, the four remaining cane samples, containing either high ash content or processing added impurities, exhibited only one large endothermic DSC peak. Understanding the Thermal Behavior differences between and within sucrose sources is of substantial importance to the food industry, especially in applications involving heat, such as baking, extrusion cooking, pasteurization, and drying.

John E. Smugeresky - One of the best experts on this subject based on the ideXlab platform.

  • Understanding Thermal Behavior in the LENS process
    Materials & Design, 1999
    Co-Authors: Michelle L. Griffith, M.e. Schlienger, L.d. Harwell, M.s Oliver, Michael Dean Baldwin, Mark T. Ensz, M Essien, J Brooks, Charles V. Robino, John E. Smugeresky
    Abstract:

    Abstract In direct laser metal deposition technologies, such as the laser engineered net shaping (LENS) process, it is important to understand and control the Thermal Behavior during fabrication. With this control, components can be reliably fabricated with desired material properties. This paper will describe the use of contact and imaging techniques to monitor the Thermal signature during LENS processing. Development of an understanding of solidification Behavior, residual stress, and microstructural evolution with respect to Thermal Behavior will be discussed.

  • Understanding Thermal Behavior in Lens Processing of Structural Materials
    1998
    Co-Authors: Mark T. Ensz, Michelle L. Griffith, M.e. Schlienger, L.d. Harwell, Charles V. Robino, John E. Smugeresky, D.l. Greene, William H. Hofmeister, Drew V. Nelson, M. J. Wert
    Abstract:

    In direct laser metal deposition technologies, such as the Laser (LENS) process, it is important to understand and control the Engineered Net Shaping Thermal Behavior during fabrication. With this control, components can be reliably fabricated with desired structural material properties. This talk will describe the use of contact and imaging techniques to monitor the Thermal signature during LENS processing. Recent results show a direct correlation between Thermal history and material properties, where the residual stress magnitude decreases as the laser power, and therefore Thermal signature, increases. Development of an understanding of solidification Behavior, residual stress, and microstructural evolution with respect to Thermal Behavior will be discussed.

M. Al-nimr - One of the best experts on this subject based on the ideXlab platform.

  • The phase-lag concept in the Thermal Behavior of lumped systems
    Heat and Mass Transfer, 2001
    Co-Authors: M. Al-nimr, O. M. Haddad
    Abstract:

    The phase-lag concept in the wave theory of heat conduction is extended to describe the Thermal Behavior of lumped systems. It is assumed that a phase-lag exists between the convection heat flux from the lumped system and the temperature difference between the lumped system and its surroundings. It is found that the dimensionless delay time τ is an important parameter in specifying the qualitative Behavior of the lumped system. The phase-lag concept has no significant effects on the Thermal Behavior of lumped systems having τ 1/4 and these changes are enhanced as τ increases. However, it is shown that the Thermal Behavior of systems having τ > 1/4 violates the second law of thermodynamics. The physical reasoning for this violation is explained. Also, the phase-lag concept is extended to describe the Thermal Behavior of composite system which consists of two domains each is lumped at different temperature.

  • Dynamic Thermal Behavior of a brake system
    International Communications in Heat and Mass Transfer, 2001
    Co-Authors: Mona Naji, M. Al-nimr
    Abstract:

    A mathematical model is presented to describe the Thermal Behavior of a brake system that consists of shoe and drum. The model is solved analytically using Green's function method for any type of the stopping braking action. In terms of the obtained solutions, the transient temperature distribution of the brake is described. The Thermal Behavior is investigated for three specified braking actions that are the impulse, unit step and trigonometric stopping actions.

  • Transient Thermal Behavior of a cylindrical brake system
    Heat and Mass Transfer, 2000
    Co-Authors: Mona Naji, M. Al-nimr, Shadi Masoud
    Abstract:

    A mathematical model is presented to describe the Thermal Behavior of a brake system which consists of shoe and drum. The model is solved analytically using Green's function method for any type of the stopping braking action. In terms of the obtained solutions, the transient temperature distribution of the brake is described. The Thermal Behavior is investigated for three specified braking actions which are the impulse, unit step and trigonometric stopping actions.

  • Thermal Behavior of insulated electric wires producing pulsating signals
    Heat Transfer Engineering, 1999
    Co-Authors: M. Al-nimr, M. R. Abdallah
    Abstract:

    A model describing the transient Thermal Behavior of an insulated electric wire is presented. The transient temperatures in both conductor and insulator result from the energy generated in the conductor by means of an alternating electric current that fluctuates in any specified manner. The mathematical model is solved analytically using Green's function method. The effect of many parameters on the transient Thermal Behavior of the insulated wire is described. The cooling rate from the wire is evaluated at different values of the insulation thickness, and then the effect of different parameters on the critical thickness of insulation is investigated.

Michelle L. Griffith - One of the best experts on this subject based on the ideXlab platform.

  • Understanding Thermal Behavior in the LENS process
    Materials & Design, 1999
    Co-Authors: Michelle L. Griffith, M.e. Schlienger, L.d. Harwell, M.s Oliver, Michael Dean Baldwin, Mark T. Ensz, M Essien, J Brooks, Charles V. Robino, John E. Smugeresky
    Abstract:

    Abstract In direct laser metal deposition technologies, such as the laser engineered net shaping (LENS) process, it is important to understand and control the Thermal Behavior during fabrication. With this control, components can be reliably fabricated with desired material properties. This paper will describe the use of contact and imaging techniques to monitor the Thermal signature during LENS processing. Development of an understanding of solidification Behavior, residual stress, and microstructural evolution with respect to Thermal Behavior will be discussed.

  • Understanding Thermal Behavior in Lens Processing of Structural Materials
    1998
    Co-Authors: Mark T. Ensz, Michelle L. Griffith, M.e. Schlienger, L.d. Harwell, Charles V. Robino, John E. Smugeresky, D.l. Greene, William H. Hofmeister, Drew V. Nelson, M. J. Wert
    Abstract:

    In direct laser metal deposition technologies, such as the Laser (LENS) process, it is important to understand and control the Engineered Net Shaping Thermal Behavior during fabrication. With this control, components can be reliably fabricated with desired structural material properties. This talk will describe the use of contact and imaging techniques to monitor the Thermal signature during LENS processing. Recent results show a direct correlation between Thermal history and material properties, where the residual stress magnitude decreases as the laser power, and therefore Thermal signature, increases. Development of an understanding of solidification Behavior, residual stress, and microstructural evolution with respect to Thermal Behavior will be discussed.

  • Thermal Behavior in the LENS process
    1998
    Co-Authors: Michelle L. Griffith, M.e. Schlienger, L.d. Harwell
    Abstract:

    Direct laser metal deposition processing is a promising manufacturing technology which could significantly impact the length of time between initial concept and finished part. For adoption of this technology in the manufacturing environment, further understanding is required to ensure robust components with appropriate properties are routinely fabricated. This requires a complete understanding of the Thermal history during part fabrication and control of this Behavior. This paper will describe research to understand the Thermal Behavior for the Laser Engineered Net Shaping (LENS) process, where a component is fabricated by focusing a laser beam onto a substrate to create a molten pool in which powder particles are simultaneously injected to build each layer. The substrate is moved beneath the laser beam to deposit a thin cross section, thereby creating the desired geometry for each layer. After deposition of each layer, the powder delivery nozzle and focusing lens assembly is incremented in the positive Z-direction, thereby building a three dimensional component layer additively. It is important to control the Thermal Behavior to reproducibly fabricate parts. The ultimate intent is to monitor the Thermal signatures and to incorporate sensors and feedback algorithms to control part fabrication. With appropriate control, the geometric properties (accuracy, surface finish, low warpage) as well as the materials` properties (e.g., strength, ductility) of a component can be dialed into the part through the fabrication parameters. Thermal monitoring techniques will be described, and their particular benefits highlighted. Preliminary details in correlating Thermal Behavior with processing results will be discussed.

Robert F. Handschuh - One of the best experts on this subject based on the ideXlab platform.

  • Thermal Behavior spiral bevel gears
    2019
    Co-Authors: Robert F. Handschuh
    Abstract:

    An experimental and analytical study of the Thermal Behavior of spiral bevel gears is presented. Experimental data were taken using thermocoupled test hardware and an infrared microscope. Many operational parameters were varied to investigate their effects on the Thermal Behavior. The data taken were also used to validate the boundary conditions applied to the analytical model. A finite element-based solution sequence was developed. The three-dimensional model was developed based on the manufacturing process for these gears. Contact between the meshing gears was found using tooth contact analysis to describe the location, curvatures, orientations, and surface velocities. This information was then used in a three-dimensional Hertzian contact analysis to predict contact ellipse size and maximum pressure. From these results, an estimate of the heat flux magnitude and the location on the finite element model was made. The finite element model used time-averaged boundary conditions to permit the solution to attain steady state in a computationally efficient manner.Then time- and position-varying boundary conditions were applied to the model to analyze the cyclic heating and cooling due to the gears meshing and transferring heat to the surroundings, respectively. The model was run in this mode until the temperature Behavior stabilized. The transient flash temperature on the surface was therefore described. The analysis can be used to predict the overall expected Thermal Behavior of spiral bevel gears. The experimental and analytical results were compared for this study and also with a limited number of other studies. The experimental and analytical results attained in the current study were basically within 10% of each other for the cases compared. The experimental comparison was for bulk thermocouple locations and data taken with an infrared microscope. The results of a limited number of other studies were compared with those obtained herein and predicted the same basic Behavior.

  • Thermal Behavior of spiral bevel gears
    1993
    Co-Authors: Robert F. Handschuh
    Abstract:

    Abstract : An experimental and analytical study of the Thermal Behavior of spiral bevel gears is presented. Experimental data were taken using thermocoupled test hardware and an infrared microscope. Many operational parameters were varied to investigate their effects on the Thermal Behavior. The data taken were also used to validate the boundary conditions applied to the analytical model A finite element based solution sequence was developed. The three-dimensional model was developed based on the manufacturing process for these gears. Contact between the meshing gears was found using tooth contact analysis to describe the location, curvatures, orientations, and surface velocities. This information was then used in a three-dimensional Hertzian contact analysis to predict contact ellipse size anti maximum pressure. From these results, an estimate of the heat flux magnitude and the location on the finite element model was made. The finite element model used time-averaged boundary conditions to permit the solution to attain steady state in a computationally efficient manner. Then tune- and position-varying boundary conditions were applied to the model to analyze the cyclic heating and cooling due to the gears meshing and transferring heat to the surroundings, respectively. The model was run in this mode until the temperature Behavior stabilized. The transient flash temperature on the surface was therefore described. The analysis can be used to predict the overall expected Thermal Behavior of spiral bevel gears. The experimental and analytical results were compared for this study and also with a limited number of other studies.