Finite Element-Based Numerical Simulations to Evaluate the Influence of Wollastonite Microfibers on the Dynamic Compressive Behavior of Cementitious Composites

This paper investigates the dynamic compressive behavior of wollastonite fiber-reinforced cementitious mortars using multiscale numerical simulations. The rate dependent behavior of the multiphase heterogeneous systems is captured in a multiscale framework that implements continuum damage towards effective property prediction. The influence of wollastonite fiber content (% by mass) as cement replacement on the dynamic compressive strength and energy absorption capacity is thereafter elucidated. An average compressive strength gain of 40% is obtained for mortars with 10% wollastonite fiber content as cement replacement, as compared to the control mortar at a strain rate of 200/s. The rate dependent constitutive responses enable the computation of energy absorption, which serves as a comparative measure for elucidating the material resistance to impact loads. Approximately a 45% increase in the dynamic energy absorption capacity is observed for the mixture containing 10% wollastonite fibers, as compared to the control case. Overall, the study establishes wollastonite fibers as a sustainable and dynamic performance-enhanced alternative for partial cement replacement. Moreover, the multiscale numerical simulation approach for performance prediction can provide an efficient means for the materials designers and engineers to optimize the size and dosage of wollastonite fibers for desired mechanical performance under dynamic loading conditions

Finite Element-Based Numerical Simulations to Evaluate the Influence of Wollastonite Microfibers on the Dynamic Compressive Behavior of Cementitious Composites

This paper investigates the dynamic compressive behavior of wollastonite fiber-reinforced cementitious mortars using multiscale numerical simulations. The rate dependent behavior of the multiphase heterogeneous systems is captured in a multiscale framework that implements continuum damage towards effective property prediction. The influence of wollastonite fiber content (% by mass) as cement replacement on the dynamic compressive strength and energy absorption capacity is thereafter elucidated. An average compressive strength gain of 40% is obtained for mortars with 10% wollastonite fiber content as cement replacement, as compared to the control mortar at a strain rate of 200/s. The rate dependent constitutive responses enable the computation of energy absorption, which serves as a comparative measure for elucidating the material resistance to impact loads. Approximately a 45% increase in the dynamic energy absorption capacity is observed for the mixture containing 10% wollastonite fibers, as compared to the control case. Overall, the study establishes wollastonite fibers as a sustainable and dynamic performance-enhanced alternative for partial cement replacement. Moreover, the multiscale numerical simulation approach for performance prediction can provide an efficient means for the materials designers and engineers to optimize the size and dosage of wollastonite fibers for desired mechanical performance under dynamic loading conditions

Fracture response of wollastonite fiber-reinforced cementitious composites: Evaluation using micro-indentation and finite element simulation

The paper presents indentation studies on wollastonite fiber incorporated cementitious systems. The acicular nature of the fibers is poised to delay the coalescence of micro-cracks in such systems thus leading to tougher building materials. Towards that end, load-penetration depth results from the indentation studies are employed to ascertain elastic and fracture properties of wollastonite-incorporated cementitious composites. While up to 10% mass-based cement-replacement by wollastonite results in comparable elastic moduli as compared to conventional binders, the fracture toughness increases by as much as 33%. In order to gain insights into the toughening mechanisms brought about by the fine fibers, a microstructure-guided numerical simulation strategy is adopted towards effective fracture performance prediction. The performance enhancement of the wollastonite systems is corroborated by the finite element-based simulations carried out on the virtual microstructures that accurately capture the heterogeneity of such systems. Besides fracture performance enhancement, the wollastonite-incorporated cementitious systems also contribute towards development of sustainable cement replacing compositions. Moreover, the micromechanical predictive tool developed in this study facilitate efficient means to tune the materials structure for desired performance

Elucidating the auxetic behavior of cementitious cellular composites using finite element analysis and interpretable machine learning

With the advent of 3D printing, auxetic cellular cementitious composites (ACCCs) have recently garnered significant attention owing to their unique mechanical performance. To enable seamless performance prediction of the ACCCs, interpretable machine learning (ML)-based approaches can provide efficient means. However, the prediction of Poisson’s ratio using such ML approaches requires large and consistent datasets which is not readily available for ACCCs. To address this challenge, this paper synergistically integrates a finite element analysis (FEA)-based framework with ML to predict the Poisson’s ratios. In particular, the FEA-based approach is used to generate a dataset containing 850 combinations of different mesoscale architectural void features. The dataset is leveraged to develop an ML-based prediction tool using a feed-forward multilayer perceptron-based neural network (NN) approach which shows excellent prediction efficacy. To shed light on the relative influence of the design parameters on the auxetic behavior of the ACCCs, Shapley additive explanations (SHAP) is employed, which establishes the volume fraction of voids as the most influential parameter in inducing auxetic behavior. Overall, this paper develops an efficient approach to evaluate geometry-dependent auxetic behaviors for cementitious materials which can be used as a starting point toward the design and development of auxetic behavior in cementitious composites

Dynamic compressive behavior of metallic particulate-reinforced cementitious composites: SHPB experiments and numerical simulations

An experimental and numerical evaluation on the dynamic compressive response of mortars containing up to 20% waste iron powder as sand replacement is presented in this paper. The dynamic response is evaluated using split Hopkinson pressure bar (SHPB) apparatus under high strain rates (up to 250/s). The elongated iron particulates present in the iron powder-incorporated mortars warrant significantly improved compressive strength and energy absorption capacity at high strain rates. Multiscale numerical simulations are performed with a view to develop a tool that facilitates microstructure-guided design of these particulate-reinforced mortars for efficient dynamic performance. The dynamic compressive response of particulate-reinforced mortars is simulated adopting a numerical approach that incorporates strain rate-dependent damage in a continuum micromechanics framework. The simulated dynamic compressive strengths and energy absorption capacities for mortars with various iron powder content exhibit good correlation with the experimental observations thereby validating the efficacy of the simulation approach

Anthropometric Measurements in Hemodialysis Patients

OBJECTIVE : In malnourished patients, in anthropometric measurements such as a decrease in the body-mass index (BMI), the triceps skinfold (TSF) thickness and the mid-upper arm circumference (MUAC) are often determined along with weight loss. Our aim in this study was to evaluate the nutritional status of chronic hemodialysis patients by taking anthropometric measurements

A Case of Newly Diagnosed Klippel Trenaunay Weber Syndrome Presenting with Nephrotic Syndrome

Klippel Trenaunay Weber syndrome (KTWS) is a rare disease characterized by hemihypertrophy, variceal enlargement of the veins, and arteriovenous (AV) malformations. Renal involvement in KTWS is not known except in rare case reports. Herein, we present a case of KTWS with nephrotic syndrome. A 52-year-old male was admitted due to dyspnea and swelling of the body for the last three months. The pathological physical findings were diffuse edema, decreased lung sounds at the right basal site, increased diameter and decreased length of the left leg compared with the right one, diffuse variceal enlargements, and a few hemangiomatous lesions on the left leg. The pathological laboratory findings were hypoalbuminemia, hyperlipidemia, increased creatinine level (1.23 mg/dL), and proteinuria (7.6 g/day). Radiographic pathological findings were cystic lesions in the liver, spleen, and kidneys, splenomegaly, AV malformation on the left posterolateral thigh, and hypertrophy of the soft tissues of the proximal left leg. He was diagnosed to have KTWS with these findings. Renal biopsy was performed to determine the cause of nephrotic syndrome. The pathologic examination was consistent with focal segmental sclerosis (FSGS). He was started on oral methylprednisolone at the dosage of 1 mg/kg and began to be followedup in the nephrology outpatient clinic