Effect of crack curvature on stress intensity factors for ASTM standard compact tension specimens

The stress intensity factors (SIF) are calculated using the method of lines for the compact tension specimen in tensile and shear loading for curved crack fronts. For the purely elastic case, it was found that as the crack front curvature increases, the SIF value at the center of the specimen decreases while increasing at the surface. For the higher values of crack front curvatures, the maximum value of the SIF occurs at an interior point located adjacent to the surface. A thickness average SIF was computed for parabolically applied shear loading. These results were used to assess the requirements of ASTM standards E399-71 and E399-81 on the shape of crack fronts. The SIF is assumed to reflect the average stress environment near the crack edge

Three-dimensional elastic stress and displacement analysis of finite geometry solids containing cracks

The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement fields in finite geometry bars containing central, surface, and double-edge cracks under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Normal stresses and the stress intensity factor variation along the crack periphery are calculated using the obtained displacement field. The reported results demonstrate the usefulness of this method in calculating stress intensity factors for commonly encountered crack geometries in finite solids

Three-dimensional elastic stress and displacement analysis of finite geometry solids containing cracks

The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement distributions in various bodies containing cracks. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. When decoupling the equations and their boundary conditions is not possible, the use of a successive approximation procedure permits the analytical solution of the resulting ordinary differential equations. The results obtained show a considerable potential for using this method in the three-dimensional analysis of finite geometry solids and suggest a possible extension of this technique to nonlinear material behavior

Stress analysis and stress intensity factors for finite geometry solids containing rectangular surface cracks

The line method of analysis is applied to the Navier-Cauchy equations of elastic equilibrium to calculate the displacement field in a finite geometry bar containing a variable depth rectangular surface crack under extensionally applied uniform loading. The application of this method to these equations leads to coupled sets of simultaneous ordinary differential equations whose solutions are obtained along sets of lines in a discretized region. Using the obtained displacement field, normal stresses and the stress intensity factor variation along the crack periphery are calculated for different crack depth to bar thickness ratios. Crack opening displacements and stress intensity factors are also obtained for a through-thickness, center cracked bar with variable thickness. The reported results show a considerable potential for using this method in calculating stress intensity factors for commonly encountered surface crack geometries in finite solids

Sex and design in our evolutionary cousins: The perception of beauty in nature

Desde un enfoque evolutivo de la belleza, en este texto analizamos la expresión y la percepción de la belleza sexual en el reino animal. Los cerebros de los animales perciben la belleza y detectan las características del entorno que resultan más relevantes para su supervivencia. A lo largo de la evolución, los animales con reproducción sexual han explotado este proceso de detección para maximizar su atractivo para el sexo opuesto. Habitualmente, esto ha conllevado la aparición de comportamientos y rasgos de cortejo extremos. Estos son rasgos de belleza sexual. Combinando principios neurocientíficos y neuroestéticos modernos con otros provenientes de la biología evolutiva, tratamos de entender las bases biológicas y la evolución de la belleza en todos los animales, incluidos nosotros mismos.; Des d’un enfocament evolutiu de la bellesa, en aquest text analitzem l’expressió i la percepció de labellesa sexual en el regne animal. Els cervells dels animals perceben la bellesa i detecten les característiquesde l’entorn que resulten més rellevants per a la seua supervivència. Al llarg de l’evolució,els animals amb reproducció sexual han explotat aquest procés de detecció per a maximitzar el seuatractiu per a l’altre sexe. Habitualment, això ha comportat l’aparició de comportaments i trets defesteig extrems. Aquests són trets de bellesa sexual. Combinant principis neurocientífics i neuroestèticsmoderns amb altres provinents de la biologia evolutiva, tractem d’entendre les bases biològiquesi l’evolució de la bellesa en tots els animals, inclosos nosaltres mateixos.; Taking an evolutionary approach to the question of beauty, we discuss the expression and perception of sexual beauty across the animal kingdom. Animals experience beauty in their brains, and animal brains are tuned to features of the environment most relevant to their survival. Over evolutionary time, sexually reproducing animals have exploited that tuning to maximize their attractiveness to the opposite sex, often leading to extreme courtship traits and behaviors. These are the traits of sexual beauty. Combining modern principles of neuroscience and neuroaesthetics with established principles of evolutionary biology, we aim to understand the biological basis and evolution of beauty in all animals, including ourselves

COVID-19 vaccine hesitancy and anti-vaxxers – supporting healthcare workers to navigate the unvaccinated: Reflections from clinical practice

An important step in preparation for the fourth COVID-19 wave is to provide healthcare workers (HCWs) with skills to facilitate behaviour change in vaccine-hesitant patients. Convincing members of the public who are vaccine hesitant rather than anti-vaxxers should be the focus of our efforts. Our experience is that vaccine-hesitant individuals and anti-vaxxers are generally distinct cohorts, with differing reasons for their vaccine reluctance. If we are to truly address hesitancy, we must take time to understand the reasons for an individual’s hesitancy. Developing a conceptual framework and skills for HCWs during encounters with unvaccinated individuals will be important not only for shifting some to get vaccinated, but also to manage the complex emotions that HCWs will undoubtedly be forced to confront during the fourth wave