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In this paper, collapse properties of the capped-end cone tubes made from steel alloy 430 with circular holes under quasi-static axial loading have been studied experimentally and numerically. Simulations were performed using finite element LS-Dyna software and 11 types of cone with various number of holes (3, 4 and 5) and heights (20,40 and 60 mm relative to bottom base of cone) in four different thicknesses (0.2, 0.4, 0.6 and 1 mm), so, 44 different states were totally simulated and the collapse properties of them were extracted. The samples with the thickness of 0.2 mm were tested on an experimental basis in order to ensure the accuracy of the simulation results. Comparing the obtained results indicates good agreement between the experimental and numerical data. According to the obtained results, it was found that open end absorbers are more efficient compared to similar capped-end structures. Also, it was revealed that creating holes in the capped-end cone decreases the maximum force and increases crush force efficiency. In addition, it was found that creating hole farther away from the underlying base is more effective for improving the collapse properties. In the final section, the effects of thickness on the collapse properties were evaluated. The obtained results in this study can be a good guidance for investigation on the effect of discontinuity on collapse properties. [ABSTRACT FROM AUTHOR]

In this paper, the recent development of extended consecutive-interpolation 4-node quadrilateral element (XCQ4), which goes beyond certain limitations of conventional methods, is further employed to study dynamic and static thermoelastic fracture problems. In particular, static stress intensity factors (SIFs) and transient dynamic responses of two-dimensional (2-D) stationary cracks in elastic solids under thermal and thermal-mechanical loadings are investigated. In addition, simulation of quasi-static crack propagation under thermal-mechanical loading condition is also performed. To precisely capture the singularity and discontinuity of temperature, heat flux, and displacements due to the presence of crack, the unknown field variables of mechanical displacements and temperature are approximated in terms of the XCQ4 framework by different enrichment strategies, which include either the use of the conventional branch functions or the new ramp function associated with Heaviside function. Only adiabatic condition is considered on the crack surfaces. For quasi-static crack growth analysis, the maximum hoop stress criterion, which is also valid for thermo-elastic fracture mechanics, is adopted. For transient crack analyses, the inertial effect is taken into account for the interaction integral in the consideration of DSIFs. Through eight numerical examples for thermoelastic fracture problems, the validity of the XCQ4 is confirmed by a comparison of the obtained results to those derived from different approaches in previous studies. In addition, the accuracy, performance, and superior advantages of the XCQ4 over standard extended finite element approach are also demonstrated. [ABSTRACT FROM AUTHOR]

The present paper aims at investigating the homogenisation of cellular materials in view of the modelling of large but finite cellular structures. Indeed, computation costs associated with the complete modelling of such structures can be rapidly prohibitive if industrial applications are considered. The use of a homogeneous equivalent medium (HEM) for these cellular materials can be an efficient approach to address this issue, but it requires the calibration of relevant homogeneous equivalent laws (HELs). Here, the considered cellular materials are tube stackings. Various uni-axial and multi-axial loading cases have been simulated, through the finite element method, on representative volume elements of such periodic stackings. From these simulations, anisotropic compressible elasto-plastic constitutive equations have been identified for the HEL. The anisotropy of the yield surfaces is discussed depending on the pattern of the tube stacking (e.g. square or hexagonal). A validation of the identified laws is proposed by simulating uni-axial compression and simple shear tests on sandwich structures made of tube stackings for their cores. A systematic comparison, between the results obtained from the fully meshed structures and those obtained from the structures whose core has been replaced with its HEM, allows us to address the limitations of the HEM-based approach and the boundary layer effects observed on finite structures. [ABSTRACT FROM AUTHOR]