Numerical study on the effect of welding and heating treatments on strength of high strength steel column

[EN] High strength steel box columns are usually fabricated from steel slab by applying welding. The welding process can introduce residual stresses and geometric imperfections into the columns and influence the column strength. In this study, a numerical investigation on the behavior of high strength steel thin-walled box columns under the compression force was carried out. The welding processes were firstly simulated with commercial package ABAQUS in this study to find out the residual stress distributions in high strength steel box column. After that, the column behaviors under the compression were modelled with predefined field from the previous step. The effect of the welding process (including flux-core arc welding and submerged arc welding), heating treatment (including preheating and post-weld heat treatment) and geometrical imperfection on the residual stress field and box column strength was investigated and discussed.Jin, J.; Bao, W.; Liu, J.; Peng, Z. (2018). Numerical study on the effect of welding and heating treatments on strength of high strength steel column. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 667-673. https://doi.org/10.4995/ASCCS2018.2018.8370OCS66767

Numerical calculation and experiment investigation of sound field in the full model car

Currently, much interior sound field research in car is based on the car body that many parts are missed, which is not consistent with the actual condition. In addition, the research results have not been verified by experiment; few things have been done in air tightness of car. In this paper, the full car model has been used to analyze the interior sound field in car, in order to simulate the actual condition accurately. Through the comparison between the analysis results and the experiment, there was a good agreement in full frequency hand. However, there was also a clear peak in 130 Hz that may cause roar; the reason was assumed to be sealing defects. After all the sealing defects were fixed, the sound pressure in the driver’s ear was measured again and compared to the results before. It was found that seal could reduce the sound pressure, which also means the sealing performance of car must be maximized when manufacturing. The contribution coefficient of each panel towards the sound pressure in the driver’s ear in 130 Hz has been calculated by using ATV method in this paper; the result showed that the top panel of car was the main reason for the existence of the clear peak in 130 Hz. Through the replacement of original interior decoration with compound sound package structure and the change of each layer’s properties, the sound package structure with the minimum transmission sound power has been found. The results showed that the combination of (3-4-1) sound package structure is optimal (which means the damping layer thickness was 3 mm, the porous material layer thickness was 4 mm and the viscoelastic cover layer thickness was 1 mm). Besides, the combination of the damping layer with new material has shown a better acoustic performance. This scheme has been used in the top panel of car and has apparently improved the sound pressure condition in the driver’s ear

Conserved quantities for asymptotically AdS spacetimes in quadratic curvature gravity in terms of a rank-4 tensor

We investigate the conserved quantities associated to Killing isometries for asymptotically AdS spacetimes within the framework of quadratic-curvature gravity. By constructing a rank-4 tensor possessing the same index symmetries as the ones of the Riemann tensor, we propose a 2-form potential resembling the Noether one for quadratic-curvature gravity. Such a potential is compared with the results via other methods existing in the literature to establish the equivalence. Then this potential is adopted to define conserved quantities of asymptotically AdS spacetimes. As applications, we explicitly compute the mass of static spherically-symmetric spacetimes, as well as the mass and the angular momentum for rotating spacetimes, such as the four(higher)-dimensional Kerr-AdS black holes and black strings embedded in quadratic-curvature gravities. Particularly, we emphasize the conserved charges of Einstein-Gauss-Bonnet, Weyl and critical gravities, together with the ones for the asymptotically AdS solutions satisfying vacuum Einstein field equations.Comment: 50 pages, no figures, accepted by PR

Nuclear superfluidity for antimagnetic rotation in 105^{105}Cd and 106^{106}Cd

The effect of nuclear superfluidity on antimagnetic rotation bands in $^{105}$Cd and $^{106}$Cd are investigated by the cranked shell model with the pairing correlations and the blocking effects treated by a particle-number conserving method. The experimental moments of inertia and the reduced $B(E2)$ transition values are excellently reproduced. The nuclear superfluidity is essential to reproduce the experimental moments of inertia. The two-shears-like mechanism for the antimagnetic rotation is investigated by examining the shears angle, i.e., the closing of the two proton hole angular momenta, and its sensitive dependence on the nuclear superfluidity is revealed.Comment: 14 pages, 4 figure