A method which we describe as the “successive cracking method” for measuring residual stresses in a circular ring is presented. In this method, the residual stresses are evaluated using a fracture mechanics approach. The strains measured at a point on the outer edge of the ring as a crack is introduced and extended from the edge are used to deduce the residual stress distribution in the uncracked ring. Finite element analysis is carried out to examine the validity of the theoretical derivation. Experiments to measure the residual stresses in a steel ring specimen are done by the successive cracking method. For comparison purposes, the experimental results using the sectioning method are presented as well. The successive cracking method is shown to be valid, simple, and effective for measuring the two-dimensional residual stress distribution in an axisymmetric member.

DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L–H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.

A new method using thermal analysis database and optimization technique has been developed to substitute the original method what was based on trial and error. First, an original vacuum furnace was manufactured according to experiences. Modified baseline vacuum furnace which can be used in high temperature was produced from the original one by using experimental data and experiences. The results in 2 different conditions of nearly vacuum and argon ambient gas were investigated in order to define the worse but necessary condition between them. By comparing the analysis results with experimental results, the unknown thermal conductivity of insulator in high temperature has been found out. The calculated thermal conductivity of insulator has been applied to the process of thermal analysis database constructing under the condition of argon ambient gas which is the worse but necessary condition. In order to check the accuracy of constructed thermal analysis database, the interpolated results using constructed thermal analysis database have been compared with computational results. Finally, optimization study has been carried out to design an energy efficient, high temperature vacuum furnace which can fully satisfy user's design requirements by using the new method. Feasible optimal design has been obtained as a final product. With negligible computational cost, a high temperature vacuum furnace which has 31.9% reduction in the total heat was designed by using the new developed method.

NOMENCLATUREC P =specific heat of ABS sheet, J/kg.K H=thickness of total sheets, m h=heat transfer coefficient, W/m 2 .K k=thermal conductivity of ABS, 0.174 W/m.K k eq =thermal conductance, W/m.K L=half of the total thickness, m N=total number of sheets q in =inputted heat flux, W/m 2 R c =contact resistance, m․ K/W T a =average temperature, K T c =center temperature, K T s =surface temperature, K T 0 =initial temperature, K T ∞ =environmental temperature, K t=time, s t h =heating time, s ρ=density of ABS sheet, 1050 kg m -3 α=thermal diffusivity of ABS, m 2 /s η n =eigen valueObtaining a uniform thickness of the final product using thermoforming is difficult, and the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the time-dependent temperature distribution of the total sheets in the storing stage was studied because the temperature after the storing stage is the initial temperature of the heating process. An analytic solution for simulating the storing stage was derived. Using the solved analytic solution, the time-dependent temperature distribution of the total sheets was found out under the condition of assuming that the temperature-dependent specific heat of the ABS sheets was a certain constant value. Finally, the control method for a successful thermoforming using the heater power or heating time was researched in order to improve the quality of the final products. The results show that the satisfied temperature distribution can be obtained by adjusting the heater power or heating time. The method for analysis in this study will be used to improve the quality of the final products.

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