Micromechanical Damage Model for Plain Concrete Considering Propagation of Matrix Microcracks

Based on the tenets of continuum micromechanics, a damage model is developed in the present work to investigate the effect of microcracking on the constitutive relations of cement based materials such as concrete. The model considers concrete as a two phase particulate composite consisting of coarse aggregates and mortar matrix. The microcracks are assumed to be present in the matrix material. Making use of Eshelby's solution for equivalent inclusion, the stress and strain fields are evaluated at the mesoscale. A two step homogenization scheme is adopted to obtain the effective response of the composite. The crack density parameter is used as a damage variable in the formulation. Strain energy release rate, obtained from the micromechanical analysis, is used as the criterion for describing the propagation of microcracks. The effect of various mesoscopic parameters, such as aggregate content, elastic properties of the phases, microcrack density and fracture resistance of the matrix, on the overall behavior of concrete is demonstrated through a parametric study

Role of aggregate debonding on the tensile response of concrete: A micromechanical approach

A micromechanics based model has been developed to understand the effect of debonding of coarse aggregates from mortar on the macroscopic behavior of concrete under equibiaxial and uniaxial tension. Concrete is modeled as a two phase composite at the meso-scale. The interface is characterized by a bilinear cohesive law with softening. The elastic solutions of the stress and displacement fields due to the separation of the aggregate from the mortar matrix are computed at the meso-level. A homogenization scheme is implemented to obtain the overall behavior at the macro-scale. Factors such as aggregate size, aggregate content, elastic properties of the constituents and the interface properties are seen to affect the macroscopic response of concrete

Mesoscale Analysis of Fatigue Damage through Aggregate-Mortar Bond Cracks in Cementitious Composites

A micromechanics-based model is developed to study the fatigue response of cementitious composites. Microcrack growth, which is the predominant mechanism responsible for fatigue damage, is explicitly modeled at the mesoscale. The damaged state at the macroscopic scale is determined by using energetic criterion. The dissipated energy associated with each stage of microcrack propagation is computed numerically based on the elastic solutions of the stress and displacement quantities at the mesoscale. The model is used to predict the fatigue life of plain concrete beams under fatigue load cycles. The influence of the various properties of the constituent phases on the fatigue life of the composite is investigated through a parametric study

Hyaluronic acid-graphene oxide quantum dots nanoconjugate as dual purpose drug delivery and therapeutic agent in meta-inflammation

Abstract Type 2 diabetes mellitus (T2DM) predominantly considered a metabolic disease is now being considered an inflammatory disease as well due to the involvement of meta-inflammation. Obesity-induced adipose tissue inflammation (ATI) is one of the earliest phenomena in the case of meta-inflammation, leading to the advent of insulin resistance (IR) and T2DM. The key events of ATI are orchestrated by macrophages, which aggravate the inflammatory state in the tissue upon activation, ultimately leading to systemic chronic low-grade inflammation and Non-Alcoholic Steatohepatitis (NASH) through the involvement of proinflammatory cytokines. The CD44 receptor on macrophages is overexpressed in ATI, NASH, and IR. Therefore, we developed a CD44 targeted Hyaluronic Acid functionalized Graphene Oxide Quantum Dots (GOQD-HA) nanocomposite for tissue-specific delivery of metformin. Metformin-loaded GOQD-HA (GOQD-HA-Met) successfully downregulated the expression of proinflammatory cytokines and restored antioxidant status at lower doses than free metformin in both palmitic acid-induced RAW264.7 cells and diet induced obese mice. Our study revealed that the GOQD-HA nanocarrier enhanced the efficacy of Metformin primarily by acting as a therapeutic agent apart from being a drug delivery platform. The therapeutic properties of GOQD-HA stem from both HA and GOQD having anti-inflammatory and antioxidant properties respectively. This study unravels the function of GOQD-HA as a targeted drug delivery option for metformin in meta-inflammation where the nanocarrier itself acts as a therapeutic agent. Graphical Abstrac