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This study investigates the constitutive relationships for a modified bond-based peridynamic (MBB-PD) model to analyze bimaterial structures with a viscoelastic component subjected to mechanical and thermal loads. The hereditary integral viscoelastic constitutive relationship is used to model the viscoelastic behavior of a generalized Maxwell model, with viscoelastic constitutive coefficients obtained from the Prony series. To model the bimaterial interface between viscoelastic and elastic segments, various functions are proposed. Additionally, normal and shear bonds are defined as failure criteria based on critical stretches and angles. The fidelity of the proposed model is evaluated by comparing its thermoviscoelastic creep and recovery responses with finite element (FE) solutions for single and bimaterial plates. The sensitivity of the interface function to the horizon size is also examined. The results demonstrate that small horizon sizes still yield satisfactory results near the interface while reducing computational costs. Finally, the proposed MBB-PD model is applied to simulate a double cantilever beam (DCB) delamination test with a rubber interface, with predictions that are in good agreement with those from the extended finite element method (XFEM). The MBB-PD model proves to be a useful and efficient tool for analyzing bimaterial structures with viscoelastic components.

The natural origin of the fibers combined with random production flaws results in significant uncertainties in the properties of natural fiber-reinforced composites. A probabilistic assessment can help to characterize the uncertainties and evaluate the reliability of natural fiber composites, enabling their use in engineering designs. To this end, this study aims to analyze the uncertainties in the tensile strength and frequency response of a unidirectional flax/epoxy composite due to the actual variability of various input parameters, including the fiber material properties and manufacturing flaws. Based on the available data in the literature, the non-deterministic input variables were divided into normal and uniform variables using a statistical test. A computationally efficient response surface approach based on the polynomial chaos expansion was proposed to conduct the uncertainty analysis with multi-type uncertain variables. Moreover, the results were validated by experimental measurements and compared with the direct Monte Carlo simulation to demonstrate the accuracy and efficiency of the surrogate model.

Background and aimOne of the prerequisites to develop Computerised Decision Support Systems is Clinical Practice Guidelines (CPGs) which provide a systematic aid to make complex medical decisions. In order to provide an automated CPG, it is needed to have a unique structure for the CPGs. This study aims to propose a unique framework for the Persian guidelines.Materials and methods20 Persian CPGs were selected and divided into the creation and validation sets (n=10 for each). The first group was studied independently and their headings were listed; wherever possible, the headings were merged into a new heading that was applicable to all the guidelines. The developed framework was validated by the second group of the guidelines.ResultsStudied guidelines had a very heterogeneous structure. The number of original headings was 249; they were reduced to 14 main headings with 16 subheadings in a unique developed framework. The framework is able to represent and cover 100% of the guidelines.ConclusionThe heterogeneity of guidelines was high as they were not developed based on the unique framework. The proposed framework provides a layout for designing the CPGs with a homogeneous structure. Guideline developers can use this framework to develop structured CPGs. This will facilitate the integration of the guidelines into electronic medical records as well as clinical decision support systems.

This study proposes a novel modified bond-based peridynamic model based on bonds' classifications. Bonds are classified as per the equivalent hypothetical local strains into horizontal normal, vertical normal, and shear bonds. While the classical Bond-Based PeriDynamic (BB-PD) only considers the stretch of bonds, the proposed model takes into account all strain components of the bonds. A local imaginary element is considered around each bond to estimate its true strains. Constitutive relations are derived by equating the strain energies of the bonds' deformations to the strain energies of classical continuum mechanics for a generalized combined loading condition. A novel critical stretch criterion and a critical angle criterion are proposed to predict the failure of normal and shear strain bonds, respectively. Moreover, it is demonstrated that, unlike the classical BB-PD, the proposed model imposes no restrictions on the value of Poisson's ratio. The model is validated by analyzing some intact plane stress and plane strain problems subjected to mechanical and thermal loads. In addition, the deformation and damage contours, as well as the corresponding stress-strain responses, are presented and validated for various problems with pre-existing defects using the extended finite element method. [ABSTRACT FROM AUTHOR]