Bench testing of hybrid ems prototype

Aim: To test the levitation performance of a hybrid EMS prototype. Materials and Methods: a levitation test setup with a 18 mm thick steel rail was constructed on a basis of the certified test bench 1958U-10-1 for measurement in the range up to 100 kN. The attractive force was investigated by varying the air gap size and coil current. Measured data were compared with parametric simulations. Results: Experimental and numerical results agreed with the accuracy required for practical application. Conclusions: A prototype of hybrid EMS (HEMS) for maglev transport has been designed, built, and tested at JSC NIIEFA. The HEMS concept has an advantage of reduced power loss and low stray field. The bench testing has proved good levitation performance and low power consumption of the proposed design. The measured data were used to check design solutions and verify 3D numerical models of the magnets. The comparison demonstrated a good match between measurements and simulations.

Experimental Research On The Technology of Two-Pass Different Temperature Rolling For Thick Steel/Aluminum/Aluminum-Alloy Composite Plate

Thick steel/aluminum/aluminum-alloy composite plate is one of the key materials connecting steel structures and aluminum alloy structures, and has been widely used in shipbuilding industry and other fields. However, steel/aluminum/aluminum-alloy composite plates with a total thickness of more than 10 mm and a steel layer thickness of more than 5 mm are prone to problems such as inconsistent deformation of component metals and low bonding strength during the rolling process, and cannot be continuously prepared. In order to solve this problem, this article proposes a two-pass different temperature rolling process for thick steel/aluminum/aluminum-alloy composite plates, and conducts research on Q235B steel, 1060 aluminum and 5083 aluminum alloy as component metals. The results show that the process is reliable. It can prepare Q235B/1060/5083 composite plates with a thickness of 15.65 mm without oxygen protection measures. Meanwhile, the interfacial shear and pull-off strength of the composite plates obtained under different experimental conditions in this article are higher than the requirements of the US military standards MIL-J-24445A and Chinese ship standard CB20091-2012. And the composite plates showed good performance in 90° and 137° bending tests without obvious defects. Under the best condition of them, a 1.48 μm interlocking diffusion layer was formed at the steel/aluminum interface of the composite plates, and the interfacial shear strength exceeded 70 MPa, and the interfacial pull-off strength exceeded 110 MPa. Finally, according to the experimental results, the reasons for the feasibility of the two-pass different rolling of thick steel/aluminum/aluminum-alloy composite plates are given.

Comparison of the Efficiency of Two Types of Heat Exchangers with Parallel Plates Made of Varied Materials

The paper discusses two mathematical models for the air flow through a plate heat exchanger with parallel plates. The first exhausts the used air and then supplies the fresh air. The second exhausts the used air above the plate and simultaneously supplies fresh air under it (counter-flow exchanger). In both cases, the exhaust air heat is used to heat the supply air. The purpose of the research is to verify which exchanger uses the exhaust air heat more efficiently. The method of the Trefftz function was used to determine approximate solutions of the analysed problems. The results obtained for 1.2 mm thick steel, aluminium, and copper plates and for external winter, summer, and spring–autumn temperatures are discussed. The results indicate that steel is the best material for a plate heat exchanger, and the counter-flow exchanger is more efficient of the two. Thanks to the use of thin steel plates and the reduction of the air exchange time to a few minutes, cheap and efficient counter-flow exchangers can be obtained.

Influence of Post-Weld Heat Treatment on Microstructure and Toughness Properties of 13MnNiMoR High Strength Low Alloy Steel Weld Joint

Weld and base metals require hot or cold working during the steel equipment manufacturing process. As a result, the components should be subjected to a normalizing heat treatment in order to recover their mechanical properties. In this study, the submerged-arc welding of the high strength low alloy (HSLA) thick steel plate(13MnNiMoR) is adapted for the vessel head under the normalizing and tempering heat treatment. The findings showed that the material toughness decreases after heating to simulate a vessel head forming process. The stamping process is carried out under the conditions of 980 °C for one hour, normalizing at 920 °C for 1 h and tempering between 600–660 °C for 2 h, respectively. The martensite-austenite (M-A) constituent is distributed in granular bainite and the boundary of austenite in island constituent. Therefore, it was deemed to be the most detrimental to Charpy-V impact toughness. Between normalizing and tempering, intercritical normalizing at 740 °C was added. As a result of the ferrite with fine particles M-A constituent, the toughness increases significantly.

Brittle Fracture Avoidance Technology in Large Structures with Thick Steel Plates

The 460-MPa-class steel was developed by thermomechanical control process for shipbuilding, and the maximum plate thickness was 100 mm, which has the fine grain size as 5–20 µm. The surfaces were studied in terms of micro and nano structures, surface roughness, and surface energy to evaluate the effect of fracture toughness in large steel structure. The thick steel plate has possibility to occur unstable fracture because the fracture toughness will be decrease with increase of thickness. The increase in the temperature in thermomechanical control process accelerated the surface energy and created both micro and nano structures on the surfaces more effectively. It was effective to avoid brittle fracture in the base metal when the brittle crack was deviated into base metal. The developed 460-MPa-class steel plate improves the brittle fracture safety despite being a thick steel plate through the fine grain size. They had to be designed in such a manner as to avoid crack initiation, especially in welded joints. In this study, brittle crack arrest designs were developed for large weld construction using arrest design concept and micro and nano structures in high strength steel plate.