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A strategy based on representative volume element (RVE) was proposed to investigate the mechanical behavior of cold-drawn pearlitic steels at multiscale. Firstly, a finite element model based on macroscale was used to simulate the cold drawing. The partial mesh of the model was refined to obtain a RVE-scale element, and the elastic-plastic strain of this element were extracted and mapped to the RVE model. For further research, a high-resolution RVE model based on the crystal plasticity finite element method (CPFEM) was established to investigate the mechanical behavior of the pearlite. In addition, a new method of hierarchical partition was used for geometric modeling. Crucially, the simulated pole figures were in high agreement with the experimental results, both prominently showing an α-fiber texture. The final results indicated that the plasticity and strength of the pearlitic steels were determined by the coordinated deformation between pearlite nodules and the interaction between ferrite and cementite.

With the rapid development of rail vehicles, 301L strip has become the main material of the rail vehicles, and its flatness quality has got much attention. Meanwhile, 20-roll mill becomes the most important cold rolling equipment for 301L strip forming, because of its high precision and wide application. To study the flatness control theory of cold rolling 301L strip in 20-roll mill, a finite element model is established based on elastoplastic theory. The stress–strain field is used to characterize the strip flatness under different rolling parameters. After analysis, the results show that the front and back tension have the most obvious effects on strip flatness. The friction coefficient and rolling speed are beneficial to the control of the strip flatness when they increase within a certain range.

To provide new possibilities for electrode materials, a new welding method of Al/Ni dissimilar metals was studied using molecular dynamics in this research. The effective bonding between aluminum and nickel was achieved by Al-Ni reactive nano-multilayers (RNMLs). The tensile strength of the bonded component was 57 % higher than that of diffusion-bonded Al/Ni nanowires. First, compared to the two single-crystal metals before bonding, the Young’s modulus of the bonded component was 48.88 GPa higher than that of single-crystal aluminum and 68.09 GPa lower than that of single-crystal nickel. Furthermore, a large number of stair-rod dislocations and nano-coherent twins were generated in the process of tensile loading, improving the mechanical performance of the bonded component. Second, as the atomic ratio of Al-Ni RNMLs increased, the tensile strength decreased first to 6.22 GPa and then continuously increased to 7.48 GPa, and the Young’s modulus increased from 113.73 to 141.73 GPa and remained stable. When the atomic ratio was 1.98, Shockley dislocations and stair-rod dislocations were more easily generated. Similarly, an ignition temperature of 830 K resulted in the highest tensile strength of the bonded components among all of the RNMLs ignition temperatures.

The Ms7.0 Lushan earthquake on April 20, 2013 is another destructive event in China since the Ms8.0 Wenchuan earthquake in 2008 and Ms7.1 Yushu earthquake in 2010. A large number of strong motion recordings were accumulated by the National Strong Motion Observation Network System of China. The maximum peak ground acceleration (PGA) at Station 51BXD in Baoxing Country is recorded as −1,005.3 cm/s2, which is even larger than the maximum one in the Wenchuan earthquake. A field survey around three typical strong motion stations confirms that the earthquake damage is consistent with the issued map of macroseismic intensity. For the oscillation period 0.3–1.0 s which is the common natural period range of the Chinese civil building, a comparison shows that the observed response spectrums are considerably smaller than the designed values in the Chinese code and this could be one of the reasons that the macroseismic intensity is lower than what we expected despite the high amplitude of PGAs. The Housner spectral intensities from 16 stations are also basically correlated with their macroseismic intensities, and the empirical distribution of spectral intensities from Lushan and Wenchuan Earthquakes under the Chinese scale is almost identical with those under the European scale.

A Ms7.0 earthquake was occurred on April 20, 2013 in Lushan Country, Sichuan Province, China, with the maximum seismic intensity of IX. It caused 196 death,, 21 missing and 11470 injured. During the main shock, 114 strong motion recordings were accumulated by the National Strong Motion Observation Network System (NSMONS) of China and 63 recordings by the Local Earthquake Intensity Reporting Network of Chengdu City. There is a common question why it didn¡¯t cause the heavy damage with the large ground motion(PGA) almost as the same level of Wenchuan Earthquake. In this paper, the characteristics of the amplitude, duration and spectrum and the potential effect on the earthquake damage were analyzed for Lushan Earthquake. The results show that the PGAs of ground motion in Lushan Earthquake are in accordance with the equation commonly used in China, but larger than the one used in fifth-generation ground motion zoning map, while the PGVs match well. The significant durations and bracketed durations are both larger than the global empirical prediction equation, and the attenuation of bracketed duration is slower than the global level. The acceleration response spectra with 5% damping ratio of 11 typical large recordings all have the peak periods around 0.1-0.2s where the spectral acceleration is considerably larger than the design spectra of Chinese Code, and notably smaller when the period larger than 0.3s.The damage that relatively slight in Lushan Earthquake could be inferred that the PGVs are small and the spectral acceleration is drastically smaller than the design spectra of the Code during the periods 0.3-1.0s corresponding to 3-10 stories RC buildings in the moderate and small cities and towns of China.

Excessively large amplitude excitations resulting from earthquakes, explosions, or mechanically vibrated systems are found to generate macroscopic and microscopic mechanisms that have beneficial effects on the production of wellbores. A downhole harmonic vibration oil-displacement system (DHVOS) that generates a sudden large amplitude excitation to the liquid in the wellbore was developed by researchers at CNPC (China National Petroleum Company). Compared with other downhole artificial vibration systems, the DHVOS system is a heavy-duty unit that can provide long period operations and large amplitude excitations. This system has been implemented in CNPC's oil fields such as Liaohe, Huabei, Shengli and Zhongyuan. The DHVOS system provides a harmonic vibration frequency of 88 shocks per minute with each shock having 5-ton strength. More than 100 oil-producing wells have been stimulated with the downhole vibration system since 1997. The field results demonstrated that periodic application of large amplitude excitation to oil reservoirs led to increased oil production rates and decreased produced fluid water content. The observed oil production-rate increments ranged from 27.5% to over 400% with an average increment of 47.6% compared to the pre-vibration production rates. The reduction in water oil ratio (WOR) varied 10% to 75% with an average of 48.4% in WOR reduction.