correlation among energy based fatigue curves and fatigue design approaches

Abstract In this paper, with reference to the strain controlled fatigue characterization of AISI 304L stainless steel, the correlations between plain material fatigue curves based on different definitions of the strain energy densities, namely the elastic, plastic and elastoplastic strain energy densities evaluated under the cyclic stress-strain curve and the plastic strain hysteresis energy density (per cycle and total at fracture) are investigated. On this basis, a diagram showing the link among the different energy-based fatigue curves is proposed and is applied to find the correlation between plain material strain energy density fatigue curves and some fatigue strength assessment methods for notched structural components, namely the one based on the experimental evaluation of the heat energy dissipated by the material per cycle and the one based on the evaluation of the linear elastic strain energy density, averaged in a properly defined structural volume

The Heat Energy Dissipated in a Control Volume to Correlate the Fatigue Strength of Bluntly and Severely Notched Stainless Steel Specimens

Abstract In previously published papers by the authors, the specific heat energy loss per cycle (the Q parameter) was used to rationalize about 120 experimental results generated from constant amplitude, push-pull, stress- or strain-controlled fatigue tests on plain and notched hot rolled AISI 304 L stainless steel specimens as well as from cold drawn un-notched bars of the same steel, tested under fully-reversed axial or torsional fatigue loadings. It has been shown that Q can be estimated starting from the cooling gradient measured at the critical point immediately after the fatigue test has been stopped. Concerning notched specimens, it was noted that a 3 mm notch tip radius was close to the limitation of applicability of the adopted temperature sensor, consisting in 0.127-mm-diameter thermocouples, because of the 1.5-to-2 mm diameter spot of the glue which prevented to measure the maximum temperature level. In this paper, the fatigue-damage-index effectiveness of Q parameter was investigated, carrying out fully reversed axial fatigue tests on 4-mm-thick AISI 304L specimens, having 3, 1 and 0.5 mm notch tip radii. The cooling gradients were measured by using an infrared camera, characterized by a 20 μm/pixels spatial resolution. As a result, all new fatigue data could be rationalized using the same scatter band published previously by the authors

Uniform scatter bands to analyse the fatigue strength of welded joints

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Analysis of the structural behavior of an innovative reinforced ski boot

Abstract The effect on the boot structural behavior of a stiffening aluminum bootboard has been investigated by laboratory and field tests. Stiffness tests on the boot with the bootboard screwed to the shell (state ON) showed a 20% increase with respect to the unscrewed state (OFF). Lateral stiffness tests conducted on a servohydraulic test bench together with motion capture techniques did not show significant increases due to the bootboard. Strain gauges applied to the bootboard for measuring torsion and bending moments in the field confirmed the intervention of the bootboard torsional stiffness at the edge changes during slalom turns

Development of an instrumented anthropomorphic dummy for the study of impacts and falls in skiing

Abstract The development of anthropomorphic dummies to be used during impact and fall tests in skiing is presented. The dummies allow introducing in the impacts the realistic conditions of skiing equipment against the safety barriers; on the other side, the dummies can wear protective devices whose performance can be evaluated during full scale simulations. The concept, design, construction and calibration of the dummies during the INTERREG SkiProTech project are presented to explain the possibilities of applications of such devices in research

analysis and comparison of some lefm parameters

Abstract This paper presents and analyses a possible extension of the well-known mean Strain Energy Density approach, proposed and developed by Paolo Lazzarin for the strength characterization and for the structural analysis of sharp notches. The new parameter, that here will be defined and discussed only for the case of a crack subjected to mode I loading conditions, will be shown to be able to characterize the superficial energy per unity of area due to the presence of a crack in a plate. Then it can be considered to be an Intensity Factor, in analogy to the Stress Intensity Factor KI. For this reason it will be called the Strain Energy Density Intensity Factor (SEDIF). Aim of the introduction of this new approach is to simplify both the characterization of the material and the structural analysis of the components, since the proposed parameter does not depend on the strength of an un-notched specimen taken as reference and does not need the evaluation of the radius R0 of the area to be considered for the evaluation of SED. Two in some way similar parameters (the J integral and the S factor proposed by Sih) will be discussed and compared to the proposed Strain Energy Density Intensity Factor

Madin Darby Canine Kidney : A new cell line for Pneumocystis carinii in vitro culture

Pneumocystis carinii pneumonia (PCP) is a highly frequent cause of morbidity and mortality in immunocompromised subjects, particularly in HIV-infected ones. The biology of P. Carinii is poorly understood because of the lack of reliable synthetic media or adequate cell lines to grow this opportunistic pathogen in continuous culture. We reported the suitability of the MDCK (Madin Darby Canine Kidney, ATTC CCL 34) cell line to support the temporary microorganism's growth in vitro and the experimental pharmacological trials, in comparison with the HEL 299 cell line, used as reference standard

Haplotype affinities resolve a major component of goat (<i>Capra hircus</i>) MtDNA D-loop diversity and reveal specific features of the Sardinian stock

Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity. We identified haplotype groups overrepresented in Sardinian goats as a result of founder effects. We found that breeders maintain diversity of matrilines most likely through equalization of the reproductive potential. Moreover, the relevant amount of inter-farm mtDNA diversity found does not increase proportionally with distance. Our results illustrate the effects of breeding practices on the composition of maternal gene pool and identify mtDNA types that may be considered in projects aimed at retrieving the maternal component of the oldest breeds of Sardinia.</br

The ACROBAT 2022 Challenge: Automatic Registration Of Breast Cancer Tissue

The alignment of tissue between histopathological whole-slide-images (WSI) is crucial for research and clinical applications. Advances in computing, deep learning, and availability of large WSI datasets have revolutionised WSI analysis. Therefore, the current state-of-the-art in WSI registration is unclear. To address this, we conducted the ACROBAT challenge, based on the largest WSI registration dataset to date, including 4,212 WSIs from 1,152 breast cancer patients. The challenge objective was to align WSIs of tissue that was stained with routine diagnostic immunohistochemistry to its H&E-stained counterpart. We compare the performance of eight WSI registration algorithms, including an investigation of the impact of different WSI properties and clinical covariates. We find that conceptually distinct WSI registration methods can lead to highly accurate registration performances and identify covariates that impact performances across methods. These results establish the current state-of-the-art in WSI registration and guide researchers in selecting and developing methods

Molecular alterations in key-regulator genes among patients with T4 breast carcinoma

Background: Prognostic factors in patients who are diagnosed with T4 breast carcinomas are widely awaited. We here evaluated the clinical role of some molecular alterations involved in tumorigenesis in a well-characterized cohort of T4 breast cancer patients with a long follow-up period. Methods: A consecutive series of 53 patients with T4 breast carcinoma was enrolled between 1992 and 2001 in Sardinia, and observed up for a median of 125 months. Archival paraffin-embedded tissue sections were used for immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) analyses, in order to assess alterations in expression levels of survivin, p53, and pERK1-2 proteins as well as in amplification of CyclinD1 and h-prune genes. The Kaplan-Meier and Cox regression methods were used for survival assessment and statistical analysis. Results: Overall, patients carrying increased expression of pERK1-2 (p = 0.027) and survivin (p = 0.008) proteins as well as amplification of h-prune gene (p = 0.045) presented a statistically-significant poorer overall survival in comparison with cases found negative for such alterations. After multivariate analysis, the pathological response to primary chemotherapy and the survivin overexpression in primary carcinoma represented the main parameters with a role as independent prognostic factors in our series. Conclusions: Although retrospective, our study identified some molecular parameters with a significant impact on prediction of the response to therapy or prognosis among T4 breast cancer patients. Further large prospective studies are needed in order to validate the use of such markers for the management of these patients