As an asphalt modifier, diatomite could improve the road performance of asphalt. The adsorption property of diatomite was varied with different compositions of asphalt. The result suggested that diatomite with a developed mesoporous structure could effectively adsorb the lower molecular group and lower polar aromatic molecules, whereas it could not adsorb the asphaltene and resins. In addition, the adsorption amount was related to the curing time. The anchorage was formed after certain molecules in asphalt were adsorbed by diatomite and improved the property of asphalt mastic.
The present study considers the results of a structural risk analysis for a 170 000 m 3 vessel with Ice Class IA classification operating from the Baltic Sea to Quebec, Canada. The target vessel is characterized by a Gaz Transport/Technigas (GTT) NO96 containment system for liquified natural gas (LNG) cargo. The capacity of the double-hull structure has been assessed considering inner hull deflection as the critical factor for the safety of the containment system. This capacity is compared with accidental ice load, termed as 'demand' to the LNG carrier, from ice hazards that can occur during Baltic Sea operation in winter or while operating on the Canadian east coast. Risk analysis has been performed to evaluate the risks of the considered ice features in the operation route, based on the study of capacity and demand.
Particle fracture can influence material failure and removal mechanisms in high velocity impact progress. In this paper, a coupled finite element method-smooth particle hydrodynamics numerical model of a single irregularly shaped particle erode metal surface was established to investigate the particle fracture and metal surface erosion. The Johnson–Cook model and Johnson–Holmquist-II model were introduced to describe the deformation of ductile materials and the fracture of brittle materials, respectively. Subsequently, the erosion process of a single irregularly shaped particle impacting different material properties of metal was studied. The results showed the following: (1) The JH-2 constitutive model can simulate the fracture of brittle particles accurately, and the results between simulations and experiments were in reasonable agreement. (2) The extent of particle fracture was lower on softer substrates than on the harder ones. (3) The orientation angle was a key factor affecting secondary impacts of brittle particles. (4) The rigid particle made more damage on the substrate than the brittle one under the same condition.
To achieve the secondary production in multistage fracturing wells of tight oil, milling tools are usually used to remove the multistage fracturing ball seats to achieve production with a large diameter in later. In this paper, first of all, the working mechanism of milling tools for multistage fracturing ball seats was studied and a mechanical analysis model of single abrasive grain was established. Then, an experimental system for milling tools was developed, and the experimental tests of the flat, the blade, and the slope milling tool were conducted in order. Besides, the morphology of chips and the surface morphology of the workpiece after the experiment were analyzed. Also, the working performance of milling tools was evaluated from the perspectives of working safety, working efficiency, and wear resistance of the milling tool. The results show that the torque of the milling tool increases nonlinearly with the increase in the cutting depth of the abrasive grain and increases linearly with the increase in the cutting width. Also, the chips are irregular particles and the size is mainly from 10 to 50 μm. So, the chips should be pumped up with a small pump pressure and a large displacement. Besides this, the cutting depths of the abrasive grains are from 216.20 to 635.47 μm and the bottom surface of the milling tool should be eccentric to avoid the zero point of cutting speed. Furthermore, the torque of the slope milling tool is 23.8% larger than that of the flat milling tool, which is also 30.4% smaller than that of the blade milling tool. Compared with the flat milling tool, the working efficiency of the blade milling tool improves by 79.9% and the slope milling tool improves by 111.1%. Also, the wear resistance of the blade milling tool decreases by 102.7%, while the slope milling tool declines by 32.6% when compared with the flat milling tool. Therefore, the slope milling tool has the characteristics of moderate torque, stable working conditions, the highest working efficiency, and fine wear resistance, which is preferably used to mill multistage fracturing ball seats. This study provides a theoretical basis and guidance for milling multistage fracturing ball seats on-site and realizing production with a large diameter in later stages of multistage fracturing wells.
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