Baoping Zou^*, Zhiping Liu, Weifeng Jin, Haonan Ding, Zhanyou Luo

CMES-Computer Modeling in Engineering & Sciences, Vol.134, No.1, pp. 517-539, 2023, DOI:10.32604/cmes.2022.020853

Abstract To study the dynamic mechanical properties of tuff under different environmental conditions, the tuff from an ancient quarry in Shepan Island was prepared. The impact damage to the rock was tested using a triaxial dynamic impact mechanical testing system (TDIMTS) with different ground stresses, temperatures, and groundwater pressures. The time-strain relationship, dynamic stress-strain relationship, energy dissipation law, energy-peak strain relationship, and the impact damage pattern of the tuff specimens under impact air pressures were investigated. The TDIMTS experiment on ancient underground rock mass under impact loading was also simulated using the finite element analysis software LS-DYNA based on the Holmquist-Johnson-Cook… More >

Ziwei Jiang¹, Shuaibing Li^1,*, Xiping Ma², Xingmin Li², Yongqiang Kang¹, Hongwei Li³, Haiying Dong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.132, No.1, pp. 295-317, 2022, DOI:10.32604/cmes.2022.019996

Abstract

The development and utilization of large-scale distributed power generation and the increase of impact loads represented by electric locomotives and new energy electric vehicles have brought great challenges to the stable operation of the regional power grid. To improve the prediction accuracy of power systems with source-load two-terminal uncertainties, an adaptive cubature Kalman filter algorithm based on improved initial noise covariance matrix Q0 is proposed in this paper. In the algorithm, the Q0 is used to offset the modeling error, and solves the problem of large voltage amplitude and phase fluctuation of the source-load two-terminal uncertain systems. Verification of the… More >

Clyde K Coelho, Cristobal Hiche, Aditi Chattopadhyay

Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 65-82, 2011, DOI:10.3970/sdhm.2011.007.065

Abstract Low velocity impacts on composite plates often create subsurface damage that is difficult to diagnose. Fiber Bragg grating (FBG) sensors can be used to detect subsurface damage in composite laminates due to low velocity impact. This paper focuses on the prediction of impact loading in composite structures as a function of time using a support vector regression approach. A time delay embedding feature extraction scheme is used since it can characterize the dynamics of the impact using the sensor signals. The novelty of this approach is that it can be applied on complex geometries and does not require a dense… More >

A. Rama Ch,ra Murthy¹, G.S. Palani¹, Nagesh R. Iyer¹

Structural Durability & Health Monitoring, Vol.4, No.4, pp. 221-230, 2008, DOI:10.3970/sdhm.2008.004.221

Abstract Empirical formulae based on experimental data to evaluate concrete penetration depth under impact loading are often used due to the complexity of the phenomena. Several design codes employ empirical formulae for the design of protective barriers. This paper presents the details of relative assessment of the use of well known empirical formulae for evaluation of concrete penetration depth under impact loading. The empirical formulae employed in the present studies include Conwep, Army corps, Haldar, Ammann and Whitney, UKAEA, BRL, Modified Petry and modified NDRC. Appropriate expressions and limitations for these empirical formulae have been provided. Performance of these empirical formulae… More >

T. Nishioka¹, M.Kogame², T. Fujimoto¹, G. Okamoto¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.3, pp. 113-118, 2007, DOI:10.3970/icces.2007.001.113

Abstract In this study, we observed C.G.S. fringe pattern of dynamic fracture under impact load by an ultra high-speed CCD video camera, and stress intensity factors KI, KII are evaluated from the experimental measurements. From the evaluation of stress intensity factors, local mode I condition is observed during crack propagation. On the other hand, concentrated load is obtained by the experimental devices in this study. We suggest the least square method to estimate loading value based on the C.G.S. fringe pattern analyses. More >

Zhiliang Wang^1,*, Nuocheng Tian², Jianguo Wang³, Shengqi Yang³, Guang Liu¹

CMC-Computers, Materials & Continua, Vol.59, No.1, pp. 275-296, 2019, DOI:10.32604/cmc.2019.04247

Abstract The mechanical behaviors and energy dissipation characteristics of heat-treated granite were investigated under repeated impact loading. The granite samples were firstly heat-treated at the temperature of 20°C, 200°C, 400°C, and 600°C, respectively. The thermal damage characteristics of these samples were then observed and measured before impact tests. Dynamic impact compression tests finally were carried out using a modified split-Hopkinson pressure bar under three impact velocities of 12 m/s, 15 m/s, and 18 m/s. These test results show that the mineral composition and the main oxides of the granite do not change with these treatment temperatures. The number of microcracks and… More >

B.-H. Lee¹, J.-C. Park², M.-H. Kim³, S.-C. Hwang²

CMES-Computer Modeling in Engineering & Sciences, Vol.75, No.2, pp. 89-112, 2011, DOI:10.3970/cmes.2011.075.089

Abstract The violent free-surface motions and the corresponding impact loads are numerically simulated by using the refined Moving Particle Simulation (MPS) method, which was originally proposed by Koshizuka and Oka (1996) for incompressible flows. In the present method, accuracy and efficiency are significantly improved compared to the original MPS method by using optimal source term, optimal gradient and collision models, and improved solid-boundary treatment and search of free-surface particles. The refined MPS method was verified through comparisons against Kishev et al.'s (2006) sloshing experiment. It is also demonstrated that the refined MPS method is excellent in mass conservation regardless of length… More >

J. Sladek¹, V. Sladek¹, P. H. Wen², M.H. Aliabadi³

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.2, pp. 103-118, 2006, DOI:10.3970/cmes.2006.013.103

Abstract A meshless local Petrov-Galerkin (MLPG) method is applied to solve bending problems of shear deformable shallow shells described by the Reissner theory. Both static and dynamic loads are considered. For transient elastodynamic case the Laplace-transform is used to eliminate the time dependence of the field variables. A weak formulation with a unit test function transforms the set of governing equations into local integral equations on local subdomains in the mean surface of the shell. Nodal points are randomly spread on that surface and each node is surrounded by a circular subdomain to which local integral equations are applied. The meshless… More >

Byung-Hyuk Lee¹, Se-min Jeong², Sung-Chul Hwang², Jong-Chun Park³, Moo-Hyun Kim⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.1, pp. 43-63, 2013, DOI:10.3970/cmes.2013.091.043

Abstract The violent free-surface motions interacting with floating vessels containing inner liquid tanks are investigated by using the newly developed Moving Particle Semi-implicit (MPS) method for 2-dimensional incompressible flow simulation. In the present numerical examples, many efficient and robust algorithms have been developed and applied to improve the overall quality and efficiency in solving various highly nonlinear free-surface problems and evaluating impact pressures compared to the original MPS method proposed by Koshizuka and Oka (1996). For illustration, the improved MPS method is applied to the simulation of nonlinear floating-body motions, violent sloshing motions and corresponding impact loads, and vessel motions with… More >