1. |
2. Optimization of laser spot welding parameters for 304 stainless steel thin sheets using numerical simulationJin Peng, Junhai Xia, Shihua Xie, Jie Chen, Lei Zhang, Yongtao Jiu, Yujia Li, Xiaokai Yu, Xiangyun Zhang, Nannan Chen, 2026, original scientific article Keywords: numerical simulation, stainless steel, thin plate, laser spot welding, process optimization
Published in DiRROS: 15.04.2026; Views: 232; Downloads: 148
 Full text (7,65 MB)
This document has many files! More... |
3. Numerical simulation and experimental verification of heat treatment of a saddle hollow tubeWeichi Pei, Jiawang Zhang, Rongdi Yu, Qing Huang, Shengqiang Liu, Menglong Xing, Hongchao Ji, 2025, original scientific article Keywords: 42CrMo steel, numerical simulation, microstructure, phase transformation mechanism
Published in DiRROS: 07.01.2026; Views: 592; Downloads: 306
Full text (5,15 MB)
This document has many files! More... |
4. |
5. |
6. Prediction and research of dynamic recrystallization evolution in hadfield steel turnout coresHongchao Ji, Yupeng Zeng, Xiaomin Huang, Changzhe Song, Mingming Wang, Jingsheng Li, 2025, original scientific article Keywords: dynamic recrystallization, turnout core, forging, numerical simulation, constitutive model
Published in DiRROS: 24.04.2025; Views: 841; Downloads: 522
Full text (3,68 MB)
This document has many files! More... |
7. On the thermal stability of multilayer optics for use with high X-ray intensitiesMargarita Zakharova, Zlatko Rek, Božidar Šarler, Saša Bajt, 2024, original scientific article Abstract: High-intensity X-ray free electron laser (XFEL) beams require optics made of materials with minimal radiation absorption, high diffraction efficiency, and high radiation hardness. Multilayer Laue lenses (MLLs) are diffraction-based X-ray optics that can focus XFEL beams, as already demonstrated with tungsten carbide/silicon carbide (WC/SiC)-based MLLs. However, high atomic number materials such as tungsten strongly absorb X-rays, resulting in high heat loads. Numerical simulations predict much lower heat loads in MLLs consisting of low atomic number Z materials, although such MLLs have narrower rocking curve widths. In this paper, we first screen various multilayer candidates and then focus on Mo2C/SiC multilayer due to its high diffraction efficiency. According to numerical simulations, the maximum temperature in this multilayer should remain below 300°C if the MLL made out of this multilayer is exposed to an XFEL beam of 17.5 keV photon energy, 1 mJ energy per pulse and 10 kHz pulse repetition rate. To understand the thermal stability of the Mo2C/SiC multilayer, we performed a study on the multilayers of three different periods (1.5, 5, and 12 nm) and different Mo2C to SiC ratios. We monitored their periods, crystallinity, and stress as a function of annealing temperature for two different heating rates. The results presented in this paper indicate that Mo2C/SiC-based MLLs are viable for focusing XFEL beams without being damaged under these conditions.
Keywords: x-ray optics, multilayer Laue lens, thermal stability, numerical simulation
Published in DiRROS: 20.12.2024; Views: 982; Downloads: 563
Full text (4,44 MB)
This document has many files! More... |
8. Difference between using tabulated and exact values of thermal properties of materials in numerical simulations of heat transfer through a high-performance windowMiha Jukić, Sabina Jordan, 2019, published scientific conference contribution Abstract: The thermal properties of materials, primarily the thermal conductivity, are an essential input for numerical modelling of heat transfer in buildings and building components. When determining them according to relevant European standards, it is not uncommon to encounter materials for which the exact values are not appropriately specified and the tabulated values in standards are overly conservative. In such situations, the thermal conductivity of the material can be determined by measurement. However, this approach may prove inconvenient and too expensive, especially if the material in question turns out to have little influence on the overall thermal performance of the product. It is, therefore, of great interest to know how the thermal performance is affected by choosing either the accurate (measured) or the conservative (tabulated) value of the thermal conductivity. In this work, the two approaches are compared in a practical example – a high-performance window, Jelovica Jelofuture – using numerical simulations. Our study shows that modifying the thermal properties of individual materials generally leaves the thermal transmittances of the frame (Uf) and the window (UW) almost unaffected. If all of the materials considered are modified simultaneously, Uf changes by 1–2% while the change in UW remains below 1%. However, due to their small values, the calculated changes of Uf and UW may be significantly affected (further increased or reduced) by the rounding of the results according to the relevant standards. In contrast, using the tabulated value of linear thermal transmittance (Ψg) of the junction with the glazing leads to an overestimation of UW by up to 15%.
Keywords: thermal transmittance, numerical simulation, conductivity, tabulated and exact values, practical example
Published in DiRROS: 08.03.2024; Views: 1469; Downloads: 1051
Full text (282,29 KB)
This document has many files! More... |
9. Novel thermal insulation with gas-filled cavities - assessment of thermal performance of different designs based on numerical simulations of heat transferMiha Jukić, Sabina Jordan, Danijel Lisičić, 2019, original scientific article Abstract: Not only is the energy efficiency of buildings nowadays becoming more and more important; the legislative requirements, the people’s awareness of the environmental questions and their thermal comfort expectations are also on a much higher level. All of these issues can be addressed by making the building envelope more thermally resistant. However, with the traditional thermal insulation materials the thickness of thermal insulation layers is already at the viable limits. Therefore, the development of new, more efficient thermal insulation products with a higher thermal resistance is highly promoted. Preliminary research results can be applied to models to develop and confirm the conceptual designs of such new materials. In this paper, an analysis of thermal performance is presented for a novel thermal insulation consisting of graphite polystyrene (GPS) matrix with cavities filled with an insulative gas, and a protective sheath to prevent it from leaking. Bearing in mind the suitability for later production, different configurations of the assembly were considered, regarding the matrix geometry, the type of the gas filling, and the surface emissivity of the cavities. A range of numerical simulations of heat transfer was conducted to determine the efficiency of different designs in reducing the conductive, the convective, and the radiative heat transfer. Advantages, limitations and some detailed parameters of the proposed design concepts were determined, which were then used for optimisation. The analysis of the results indicates that the equivalent thermal conductance of a GPS panel can be significantly reduced by the introduction of gas-filled cavities. The reduction is highly dependent on the type of the gas filling (thermal conductivity, viscosity, specific heat, etc.), the size of the cavities, and the cavity surface emissivity.
Keywords: gas-filled cavities, graphite polystyrene, numerical simulation, thermal insulation
Published in DiRROS: 15.09.2023; Views: 1669; Downloads: 905
Full text (1,21 MB)
This document has many files! More... |
10. |
