fatigue strength of welded joints under multiaxial non proportional loading

Abstract Fatigue behaviour of a fillet-welded tubular T-joint in the so-called H structural component of an agricultural sprayer is examined by using experimental strain measurements found in the literature and linear elastic finite element analyses. Two stress-based critical plane criteria are applied at a verification point located near the intersection between the end of brace and chord of the above-mentioned T-joint, where crack initiation and growth is experimentally observed

Biomimetics and composite materials toward efficient mobility: a review

The development of new materials has always been strictly related to the rise of new technologies and progressively efficient systems. However, cutting-edge materials might not be enough to ensure the effectiveness of a given product if the design guidelines used do not favor the specific advantages of this material. Polymeric composites are known for their excellent mechanical properties, but current manufacturing techniques and the relatively narrow expertise in the field amongst engineers impose the challenge to provide the most suitable designs to certain applications. Bio-inspired designs, supported by thousands of years of evolution of nature, have shown to be extremely profitable tools for the design of optimized yet structurally complex shapes in which the tailoring aspect of polymeric composites perfectly fit. Bearing in mind the current but old-fashioned designs of auto-parts and vehicles built with metals with little or no topological optimization, the present work addresses how biomimicry is being applied in the mobility industry nowadays to provide lightweight structures and efficient designs. A general overview of biomimicry is made regarding vehicles, approaching how the use of composite materials has already contributed to successful cases

La correspondencia de Valencia : diario de noticias : eco imparcial de la opinión y de la prensa: Año XXX Número 10040 - 1907 Febrero 26

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

A Direct Estimate of the Initial Concentration of 14C in the Mountain Aquifer of Israel

From the 18th International Radiocarbon Conference held in Wellington, New Zealand, September 1-5, 2003.Five radiocarbon analyses were performed on 5 different sources within Soreq Cave, which was used as a model for the Judea Group Aquifer of Israel (pMCq0). The transit time of rainwater through the roof of the cave to sources within it had been determined with tritium. From this information, the year of deposition of rain on the roof of the cave, which later appeared in one of the sources, was estimated and the atmospheric 14C concentration at that time was ascertained (pMCa0). The parameter Q = pMCq0 / pMCa0 was found to be Q = 0.60 +/0.04. This makes it possible to calculate the age of water in any well in the Judea Group Aquifer of Israel by measuring its 14C concentration (pMCqt) by use of the decay equation and applying Q.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

A Direct Estimate of the Initial Concentration of 14

From the 18th International Radiocarbon Conference held in Wellington, New Zealand, September 1-5, 2003.Five radiocarbon analyses were performed on 5 different sources within Soreq Cave, which was used as a model for the Judea Group Aquifer of Israel (pMCq0). The transit time of rainwater through the roof of the cave to sources within it had been determined with tritium. From this information, the year of deposition of rain on the roof of the cave, which later appeared in one of the sources, was estimated and the atmospheric 14C concentration at that time was ascertained (pMCa0). The parameter Q = pMCq0 / pMCa0 was found to be Q = 0.60 +/0.04. This makes it possible to calculate the age of water in any well in the Judea Group Aquifer of Israel by measuring its 14C concentration (pMCqt) by use of the decay equation and applying Q.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Investigating the effect of interface morphology in adhesively bonded composite wavy-lap joints

Joints and interfaces are one of the key aspects of the design and production of composite structures. This paper investigates the effect of adhesive–adherend interface morphology on the mechanical behavior of wavy-lap joints with the aim to improve the mechanical performance. Intentional deviation from a flat joint plane was introduced in different bond angles (0°, 60°, 90° and 120°) and the joints were subjected to a quasi-static tensile load. Comparisons were made regarding the mechanical behavior of the conventional flat joint and the wavy joints. The visible failure modes that occurred within each of the joint configurations was also highlighted and explained. Load vs. displacement graphs were produced and compared, as well as the failure modes discussed both visually and qualitatively. It was observed that distinct interface morphologies result in variation in the load–displacement curve and damage types. The wavy-lap joints experience a considerably higher displacement due to the additional bending in the joint area, and the initial damage starts occurring at a higher displacement. However, the load level had its maximum value for the single-lap joints. Our findings provide insight for the development of different interface morphology angle variation to optimize the joints behavior, which is widely observed in some biological systems to improve their performance

A Unique Assemblage of Engraved Plaquettes from Ein Qashish South, Jezreel Valley, Israel: Figurative and Non-Figurative Symbols of Late Pleistocene Hunters-Gatherers in the Levant

Three engraved limestone plaquettes from the recently excavated Epipaleolithic open-air site Ein Qashish South in the Jezreel Valley, Israel comprise unique evidence for symbolic behavior of Late Pleistocene foragers in the Levant. The engravings, uncovered in Kebaran and Geometric Kebaran deposits (ca. 23ka and ca. 16.5ka BP), include the image of a bird—the first figurative representation known so far from a pre-Natufian Epipaleolithic—along with geometric motifs such as chevrons, crosshatchings and ladders. Some of the engravings closely resemble roughly contemporary European finds interpreted as "systems of notations" or "artificial memory systems"–records related to timing of seasonal resources and associated aggregation events of nomadic groups. Moreover, similarly looking signs and patterns are well known from the context of the local Natufian—a final Epipaleolithic culture of sedentary or semi-sedentary foragers who started practicing agriculture. The investigation of the engravings found in Ein Qashish South involves conceptualizations developed in studies of European and local parallels, a selection of ethnographic examples and preliminary microscopic observations of the plaquettes. This shows that the figurative and non-figurative images comprise a coherent assemblage of symbols that might have been applied in order to store, share and transmit information related to social and subsistence realms of mobile bands. It further suggests that the site functioned as a locality of groups' aggregation and indicates social complexity of pre-Natufian foragers in the Levant. While alterations in social and subsistence strategies can explain the varying frequency of image use characterizing different areas of the Late Pleistocene world—the apparent similarity in graphics and the mode of their application support the possibility that symbol-mediated behavior has a common and much earlier origin

Fatigue life estimation of fillet-welded tubular T-joints subjected to multiaxial loading

This study investigates the applicability of a stress-based approach to multiaxial fatigue strength assessment of fillet-welded tubular T-joints, used in the so-called ‘‘H” component of an agricultural sprayer. Experimental strain measurements on such a structural component under sprayer service conditions have been performed. A finite element analysis of the component is herein developed under linear elastic hypothesis. Finally, a stress-based critical plane criterion is applied to several material points located in the proximity of the intersection between the end of a brace and a chord of one above-mentioned T-joint, where crack nucleation is experimentally observed

Using Thermomechanical Properties to Reassess Particles’ Dispersion in Nanostructured Polymers: Size vs. Content

Nanoparticle-filled polymers (i.e., nanocomposites) can exhibit characteristics unattainable by the unfilled polymer, making them attractive to engineer structural composites. However, the transition of particulate fillers from the micron to the nanoscale requires a comprehensive understanding of how particle downsizing influences molecular interactions and organization across multiple length scales, ranging from chemical bonding to microstructural evolution. This work outlines the advancements described in the literature that have become relevant and have shaped today’s understanding of the processing–structure–property relationships in polymer nanocomposites. The main inorganic and organic particles that have been incorporated into polymers are examined first. The commonly practiced methods for nanoparticle incorporation are then highlighted. The development in mechanical properties—such as tensile strength, storage modulus and glass transition temperature—in the selected epoxy matrix nanocomposites described in the literature was specifically reviewed and discussed. The significant effect of particle content, dispersion, size, and mean free path on thermomechanical properties, commonly expressed as a function of weight percentage (wt.%) of added particles, was found to be better explained as a function of particle crowding (number of particles and distance among them). From this work, it was possible to conclude that the dramatic effect of particle size for the same tiny amount of very small and well-dispersed particles brings evidence that particle size and the particle weight content should be downscaled together