Wyniki wyszukiwania - BazTech

1

Hydroforming process of thin-walled tubular components with multiple local bulges

Cui Xiao-Lei, Guo Ju, Zhao Yuanyang, Lin Peng

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 3

art. no. e169, 2023

EN

In the hydroforming process of a thin-walled tubular component with multiple local bulges, the bulge in the middle position is almost impossible to be formed with a conventional one-step hydroforming process because of the difficult axial feeding. To solve this problem, a novel method is proposed by preforming wrinkles using selective induction heating at different positions of tube blank to aggregate materials in advance for the subsequent hydroforming of tubular component with multiple local bulges. In this paper, the wrinkling behavior of 5052 aluminum alloy tube blank under different conditions and the deformation behavior of the wrinkled tube blank in subsequent hydroforming process of tubular component with three bulges are analyzed. It is shown that the existence of wrinkles is beneficial to increase the ultimate expansion ratio of the tube blank. Moreover, the instability behavior of multiple wrinkles on 5052 aluminum alloy tube blanks under different conditions was investigated by experiments. The process parameters for prefabricating two or three wrinkles, including temperature, spacing between wrinkles, and internal pressure, were determined through a detailed experimental investigation. Finally, the defects including splitting and undercut that occur in the hydroforming of tubular component with three bulges are analyzed, and the thin-walled tubular component with three bulges was hydroformed successfully using a wrinkled tube blank obtained under the process parameters of 250 °C, 4 mm, 5.5 MPa/350 °C, 10 mm, 2 MPa/400 °C, 6 mm, 1.33 MPa. These results provide insights for the manufacturing of tubular component with multiple local bulges from hard-to-form materials.

2

Unsaturated soil properties of MICP treated granitic residual soil of Shantou region of China

Hao Li, Lin Peng, Garg Ankit

Acta Geophysica

|

2023

|

Vol. 71, no. 4

1885--1894

EN

Unsaturated soil properties such as soil–water characteristic curve (SWCC) and shear strength are required for seepage and stability flow analyses in various geo-engineering infrastructures. Microbial-induced calcite precipitation (MICP) has been recently adopted for enhancing strength of soils however, with rare focus on improvement in unsaturated soil properties of granitic residual soil. It is known that granite residual soil exhibits unique disintegration properties upon interaction with water. The objective of this study is to investigate the unsaturated properties under different vertical stresses (0, 100, 200 and 300 kPa) for MICP treated granitic residual soils. Further, microstructural characterization of MICP treated soil was conducted to analyse its water retention and shear strength, so as to provide theoretical basis for engineering application of MICP in strengthening granite residual soil. Pressure plate apparatus and FDJ-20 quadruple shear strength apparatus were utilized to obtain SWCCs and shear strength, respectively. Based on the result, it can be concluded that the treatment by MICP is found to enhance the air entry value of granitic residual soil. In addition, MICP treated soils possess higher water content than untreated soil at near-saturated condition. This is due to calcite precipitation on surface of grains and carbonate formation at contact points, which in turn reduces void ratio. However, the difference in water retention reduces with an increase in suction and also confining stress. It is possibly due to breakage of carbonate bonds at contact points at higher stresses. After five times grouting, the effective cohesion, internal friction angle and matric suction angle is found to increase very significantly.

3

Diffraction enhancement using the double sparse dictionary method

Wang Tao, Peng Suping, Lin Peng, Cui Xiaoqin, Zhou Jiawei

Acta Geophysica

|

2023

|

Vol. 71, no. 3

1259--1271

EN

Seismic diffraction delivers high-precision imaging of subsurface discontinuities and objects. As diffraction is characterised by weak energy, separating diffraction from full wavefields is an essential pre-imaging step. However, traditional diffraction separation methods generally produce unsatisfactory separation results for datasets with low signal-to-noise ratios. Accordingly, we propose a novel diffraction separation method that incorporates plane-wave destruction and the double sparse dictionary algorithm to improve separation quality. The plane-wave destruction method is used to suppress strong reflection, whereas the double sparse dictionary can simultaneously extract diffracted signals. A robust plane-wave destruction method using the Hilbert transform is employed to improve the stability and accuracy of slope estimation. The double sparse dictionary algorithm has better performance when sparsely representing seismic signals and can effectively extract weak diffraction with a high signal-to-noise ratio. Synthetic and field examples demonstrate the effectiveness of the proposed method in removing strong reflection and enhancing weak diffraction. Overall, the proposed method is conducive to detect small structures and offers a new resource for seismic structural interpretation.

4

Low-rank difraction separation using an improved MSSA algorithm

Lin Peng, Zhao Jingtao, Peng Suping

Acta Geophysica

|

2021

|

Vol. 69, no. 5

1651--1665

EN

Diffraction separation is a vital key step for high-resolution imaging of small-scale geologic discontinuities. The multichannel singular-spectrum analysis (MSSA) algorithm has exhibited adequacy for diffraction separation and refection suppression. However, the traditional MSSA algorithm is expensive because of the singular-value decomposition (SVD) operator. In addition, the common rank misidentification renders the diffraction separation highly rank-sensitive. Random noise caused by energy leakage is another problem for diffraction separation that is unresolved by the conventional MSSA. In this study, we propose a prestack diffraction separation method involving an improved MSSA algorithm. The new algorithm enables faster singular value estimation relative to the conventional SVD, with a diagonal Hankelization operator for artificial linear and random noise suppression, thereby enhancing the signal-to-noise ratio. Rank misidentification is alleviated by lowering the sensitivity to rank of the separated diffractions. Synthetic and field data are utilized to demonstrate the feasibility and superiority of the proposed method in computational efficiency and noise suppression compared with the conventional method.

5

Experimental study of dam-break-like tsunami bore impact mechanism on a container model

Chen Cheng, Chen Jun, Lin Peng, Chen Chiwei, Chen Haozhe

Polish Maritime Research

|

2020

|

nr 1

53--59

EN

Tsunami disasters have frequently occurred in recent years. More and more researchers are focusing on this topic. To investi-gate the tsunami bore impact mechanism on a container model, a multi-functional slope-changing tsunami flume is built in this study. To simulate a tsunami bore, a dam-break wave was generated by a free-falling gate in a reservoir. A needle water level gauge and a high-speed camera were used to measure the tsunami wave heights and velocities for different storage water levels in the test flume, and the corresponding Froude numbers of tsunami waves were also calculated. The factors af-fecting the movement distance of the tsunami wave impacting the container model are explored in this experiment, and the results show that the movement distance is positively correlated with the storage water level, and negatively correlated with the container density and the coast slope.

6

Lyocell Fabric Dyed with Natural Dye Extracted from Marigold Flower Using Metallic Salts

Rashdi Sayed Yaseen, Naveed Tayyab, Sanbhal Noor, Almani Sikandar, Lin Peng, Wei Wang

Autex Research Journal

|

2020

|

Vol. 20, no. 3

352--358

EN

The application of natural dyes is increasing each year due to their environmental friendliness and easy application on cellulose fibers. In this study, the natural dye from the Mexican marigold flower was extracted using a Soxhlet extraction apparatus. The extracted natural dye was applied on lyocell fabric with five different metallic salts using pre-mordanting and post-mordanting methods. It was observed that different color shade depth was achieved with different fixing agents. The color shade depth (K/S) washing fastness, light fastness, rubbing fastness, perspiration, and Fourier transform infrared (FTIR) test results of all dyed samples were excellent in both pre- and post-mordanting methods. There was no significant difference in the results between post- and pre-mordanting fixation methods. However, the results showed that mordant ferrous sulfate had higher K/S value as compared to all other mordants. The dye extracted from marigold flower showed good dyeing efficiency with mordant to excellent colorfastness tests. FTIR results showed that there was no structural change in lyocell fabrics, before and after dyeing processes. Thus, a natural dye extracted from marigold flower has shown good colorfastness properties without damaging its fiber structure.

7

Investigation of infiltration rate for soil‑biochar composites of water hyacinth

Gopal Phani, Bordoloi Sanandam, Ratnam Raval, Lin Peng, Cai Weiling, Buragohain Poly, Garg Ankit, Sreedeep S.

Acta Geophysica

|

2019

|

Vol. 67, no. 1

231--246

EN

The objective of this short communication is to investigate the interactive effects of CIF, suction and volumetric water content (VWC) on infiltration rate for compacted soil–biochar (BC) composites (0%, 5% and 10%). The biochar was produced from an invasive weed Eichhornia crassipes. Soil parameters such as suction (ψ), VWC, CIF and infiltration rate were monitored simultaneously for 63 days (9 drying–wetting cycles) in those composites. This was followed by statistical modeling using artificial neural networks. Results showed that increase in WH BC content reduced the infiltration rates. The role of CIF in determining the infiltration rate reduced (50–38%) with the addition of BC to soil. Suction played an equal role (36–35%), both for bare soil and for WH BC composites, in determining the infiltration rate. Significance of VWC in determining rate of infiltration increases (14–27%) as the BC content increases. This is more likely, as the addition of BC enhanced the water retention capacity.