Regularized local damage model for quasi-brittle material

2023-03-24T21:26:22+00:00

This paper presents an improved local damage model for quasi-brittle materials. A parameter, namely damage, in the range [0,1] is used to characterize the material from intact state to complete failure. Classical local damage model is known for low computational cost but it suffers from numerical issues such as difficult convergence and mesh-density-dependent results. Various non-local models have therefore been proposed, however the computational cost is increased, which hinders the applicability in practical problems. Furthermore, the width of the damage zone predicted by the non-local models is usually non-physically large. Here, the improvement is the introduction of the fracture energy and element-size into the calculation of damage parameters to mitigate the weakness of the local damage model, while keeping low computational cost. The employment of polygonal element is also proposed to utilize the advantage of high-accuracy, thus less number of elements (than the usual 3-node triangular or 4-node quadrilateral elements) can be used. The bi-energy norm-based equivalent strain is for the first time considered in a local damage model. This quantity is based on the maximum strain criterion, but with a modification to take into account the property of quasi-brittle materials such as concrete, limestone, etc., that load capacity in compression is higher than in tension. Accuracy and efficiency of the proposed model is investigated through comparison with reference results from experiments and other numerical methods.

Solid state lithium-ion rechargeable batteries: An overview

2023-03-24T21:15:29+00:00

Rechargeable solid-state Li-ion batteries have potential for applications in mobile devices and electric vehicles in the near future to meet the growing demand for high energy storage. Research on rechargeable solid-state Li-ion batteries has a long history and has been accelerating recently. Solid electrolytes are the most important component in the all-solid-state batteries. Solid electrolytes can be divided into the following groups: oxide groups (Perovskite Li3.3La0.56TiO3, NASICON LiTi2(PO4)3, LISICON Li14Zn(GeO4)4, and Li7La3Zr2O12 garnets), sulfide groups (Li2S – P2S5 and Li2S – P2S5 – MxS), hydride group (LiBH4, LiBH4–LiX (X=Cl, Br or I), LiBH4–LiNH2, LiNH2, Li3AlH6 and Li2NH), halogen group (LiI, spinel Li2ZnI4 and anti-perovskite Li3OCl), and polymer group (mainly polyethylene). Although electrolytes with good ionic conductivity have been used, the performance of solid-state rechargeable Li-ion batteries is still far behind that of the ones using liquid electrolytes. Along with the development of science and technology, many scientific and technical problems in solid-state rechargeable Li-ion batteries have been discovered. In this review, the major issues of solid-state rechargeable Li-ion batteries will be breifly documented: the interface between the active material (AM) and the solid electrolyte (SE), aging of the solid-solid interface, electrode structure, and fabrication methods.

VNUHCM Journal of Engineering and Technology

Regularized local damage model for quasi-brittle material

Solid state lithium-ion rechargeable batteries: An overview