Transforming structured descriptions to visual representations. An automated visualization of historical bookbinding structures.

In cultural heritage, the documentation of artefacts can be both iconographic and textual, i.e. both pictures and drawings on the one hand, and text and words on the other are used for documentation purposes. This research project aims to produce a methodology to transform automatically verbal descriptions of material objects, with a focus on bookbinding structures, into standardized and scholarly-sound visual representations. In the last few decades, the recording and management of documentation data about material objects, including bookbindings, has switched from paper-based archives to databases, but sketches and diagrams are a form of documentation still carried out mostly by hand. Diagrams hold some unique information, but often, also redundant information already secured through verbal means within the databases. This project proposes a methodology to harness verbal information stored within a database and automatically generate visual representations. A number of projects within the cultural heritage sector have applied semantic modelling to generate graphic outputs from verbal inputs. None of these has considered bookbindings and none of these relies on information already recorded within databases. Instead they develop an extra layer of modelling and typically gather more data, specifically for the purpose of generating a pictorial output. In these projects qualitative data (verbal input) is often mixed with quantitative data (measurements, scans, or other direct acquisition methods) to solve the problems of indeterminateness found in verbal descriptions. Also, none of these projects has attempted to develop a general methodology to ascertain the minimum amount ii of information that is required for successful verbal-to-visual transformations for material objects in other fields. This research has addressed these issues. The novel contributions of this research include: (i) a series of methodological recommendations for successful automated verbal-to-visual intersemiotic translations for material objects — and bookbinding structures in particular — which are possible when whole/part relationships, spatial configurations, the object’s logical form, and its prototypical shapes are communicated; (ii) the production of intersemiotic transformations for the domain of bookbinding structures; (iii) design recommendations for the generation of standardized automated prototypical drawings of bookbinding structures; (iv) the application — never considered before — of uncertainty visualization to the field of the archaeology of the book. This research also proposes the use of automatically generated diagrams as data verification tools to help identify meaningless or wrong data, thus increasing data accuracy within databases

The Peak Stress Method to assess the fatigue strength of welded joints using linear elastic finite element analyses

Abstract In fatigue design of welded joints according to the notch stress intensity factor (NSIF) approach, the weld toe profile is assumed to be a sharp V-notch having tip radius equal to zero, while the root side is assumed to be a pre-crack in the structure. The Peak Stress Method (PSM) is an engineering, FE-oriented method to estimate the NSIFs starting from the singular linear elastic peak stresses calculated at the V-notch or crack tips by using a coarse FE mesh. The element type is kept constant and the average element size can be chosen arbitrarily within a given range. The method is used in conjunction with Ansys software. The FE meshes are claimed to be coarse in comparison to those necessary to evaluate the NSIFs from the local stress distributions. Two-dimensional as well as three dimensional FE analyses can be adopted to apply the method. By using the averaged Strain Energy Density (SED, which can be expressed as a function of the relevant NSIFs) as a fatigue strength criterion, a so-called equivalent peak stress is defined to assess either weld toe or weld root fatigue failures in conjunction with a properly calibrated design curve. After presenting the theoretical background of the method, the paper presents a review of applications of the PSM relevant to steel welded joints under uniaxial as well as multiaxial fatigue loadings. Because of the relatively coarse FE analyses required and simplicity of post-processing the calculated peak stresses, the PSM might be useful in the everyday design practice

Fatigue crack onset by Finite Fracture Mechanics

Abstract The paper investigates the fatigue crack/notch sensitivity by the coupled criterion of Finite Fracture Mechanics (FFM). The approach involves two parameters: the plain specimen fatigue limit, and the threshold value of the stress intensity factor range for fatigue crack growth. Useful analytical relationships are presented. The accuracy of FFM is verified by considering experimental data available in the Literature, showing the potentiality of the coupled approach to predict size effects

VisColl: A New Collation Tool for Manuscript Studies

The principal physical feature of the book in codex format, the gathering structure, is usually not visualized within digitization projects. If this information is recorded at all, it is generally done with the use of collation formulas. There is not a standard schema for manuscript collation formulas and not all practices are able to record accurately the structure of books. There have been some attempts in the past to describe gathering structures in more formalised ways. VisColl is building on past experiences and strives to describe, visualize, and communicate the gathering structure of books. Successful applications of the new tool are presented as examples. Future versions will add functionality to link physical details of a manuscript with additional information about the content, which will enable a complete mapping of a physical manuscript

Mode I fatigue limit of V- and U-notches

none4noThe fatigue limit of structures containing V- and U-notches is assessed through the coupled stress-energy criterion of Finite Fracture Mechanics (FFM). The analysis is limited to mode I loading conditions. The FFM criterion is a critical-distance-based approach whose implementation requires the knowledge of two material properties, namely the plain material fatigue limit and the threshold value of the stress intensity factor (SIF) range for the fatigue crack growth of long cracks. Differently from other criteria based on a critical distance, the FFM crack advance results a structural parameter, being a function also of the notch geometry. The approach is validated by a comparison with experimental notch fatigue results taken from the literature and referred to a variety of materials and geometrical configurations.noneAlberto Sapora, Pietro Cornetti, Alberto Campagnolo, Giovanni MeneghettiSapora, Alberto; Cornetti, Pietro; Campagnolo, Alberto; Meneghetti, Giovann

Mode II loading in sharp V-notched components: a comparison among some recent criteria for brittle fracture assessment

Abstract Different criteria are available in the literature to assess the fracture behaviour of sharp V-notches. A typical and well-known criterion is based on the application of the notch stress intensity factors (NSIFs), which are able to quantify the intensity of the stress fields ahead of the notch tip. This work considers two recent energy-based criteria applied here to sharp V-notches. The first criterion is based on the averaged value of the strain energy density (SED), while the second one called Finite Fracture Mechanics (FFM) criterion is available under two different formulations: that by Leguillon et al. and that by Carpinteri et al. Considering the averaged SED criterion, a new expression for estimating the control radius R c under pure Mode II loading is proposed and compared with the sound expression valid under pure Mode I loading. With reference to pure Mode II loading the critical NSIF at failure can be expressed as a function of the V-notch opening angle. By adopting the three criteria considered here the expressions for the NSIFs are derived and compared. After all, the approaches are employed considering sharp V-notched brittle components under in-plane shear loading, in order to investigate the capability of each approach for the fracture assessment. With this aim a bulk of experimental data taken from the literature is used for the comparison

the peak stress method combined with 3d finite element models to assess the fatigue strength of complex welded structures

Abstract The Peak Stress Method (PSM) is a rapid and engineering application of the notch stress intensity factor (NSIF) approach for the fatigue strength assessment of welded structures, which employs the singular linear elastic peak stresses calculated by FEM using coarse meshes. First, the PSM was calibrated to rapidly estimate the NSIFs by adopting 3D, eight-node brick elements and by using the submodeling technique. Given the increasing 3D modelling of large and complex structures in the industry, the application of the PSM combined with 3D FE models has recently been speeded up by calibrating ten-node tetra elements, which allow to directly discretize complex 3D geometries making submodeling unnecessary. In the present contribution, the PSM has been calibrated by analysing several 3D mode I, II and III V-notch problems, by adopting either four-node or ten-node tetra elements. In particular, the 3D PSM with ten-node tetra elements has been extended to V-notch opening angles that had not been taken into account in a previous calibration, namely (i) 120° under mode I and (ii) 90° and 120° under mode III loadings. Then, an applicative example has been considered, which is relevant to a large-scale and rather complex steel welded structure, having overall size on the order of meters. The mesh density requirements to apply the PSM to the considered large-scale welded structure using either four-node tetra elements or ten-node tetra elements have been compared in order to assess the solution time required by the two types of FE meshes

Labeculæ Vivæ: Building a Reference Library of Stains for Medieval and Early Modern Manuscripts

Stains on manuscripts are signs indicative of their past lives left by time and usage. Reading these signals in concert with conventional information gathered from manuscripts can add to our understanding of the history and use of an object. This project, supported by a microgrant from the Council on Library and Information Resources, and run as a preliminary pilot study, provides an identified, open-access database of a number of commonly found stains in order to help researchers answer questions such as manuscript provenance, transmission, material culture, as well as scientific applications for arts questions and the innovative uses of multispectral imaging to acquire new knowledge. This paper presents the methodology and the results of the investigation and demonstrates best practices using the database for a diverse audience of scholars

Local approaches applied to fracture and fatigue problems

Intentionally designed or accidentally caused, notches, cracks or defects are inevitably present in engineering components and can induce high stress gradients when a far field loading is applied. Then, structural strength assessments are often based on the local stress and strain state in the close neighbourhood of the stress raisers. The present PhD thesis is divided into six Chapters corresponding to different research topics, all related to new applications of important and widely employed local approaches to notched or cracked structural components. In the first Chapter, the adopted local approaches, namely the Notch Stress Intensity Factor-based approach (NSIF), the averaged Strain Energy Density (SED) criterion and the Peak Stress Method (PSM), are briefly introduced and described along with their theoretical frameworks. The second Chapter deals with brittle fracture under mixed mode static loading. A wide experimental campaign has been carried out on PMMA as well as on graphite cracked and notched specimens subjected to mixed mode I+II and I+III loading. Then, all experimental results have been reanalysed by means of the SED approach. The third Chapter deals with multiaxial fatigue loadings. First, the fatigue strength of severely notched titanium grade 5 alloy, Ti-6Al-4V, has been investigated. Then, the SED criterion has been applied for the first time to an industrial case study, that is the multiaxial fatigue strength assessment of steel welded rollers produced by Rulmeca S.p.a. Finally, some remarks about the phase angle effect on sharp V-notched components under multiaxial fatigue have been drawn on the basis of a proposed analytical frame. The fourth Chapter addresses the numerical study of 3D effects in notched and cracked components. Initially, the attention has been focused on coupled modes and on the effect of different boundary conditions in 3D cracked discs and plates subjected to nominal mode III or mode II loading. Then, the presence of three-dimensional effects has been investigated both theoretically and numerically in blunt notched components under cyclic plasticity conditions. The fifth Chapter, instead, is related to the comparison between different fracture criteria. The SED approach and that based on the Finite Fracture Mechanics (FFM) have been compared considering sharp V-notches under pure mode I or mode II loading. Finally the sixth Chapter address the link between the SED approach and the Peak Stress Method (PSM). Cracks under in-plane mixed mode I+II and out-of-plane mixed mode I+III loading have been investigated. A method to rapidly evaluate the averaged SED based on the peak stresses at the crack tip has been proposed. On the basis of the derived link, some practical applications related to the fatigue strength assessment of aluminium and steel butt welded joints and of tube-to-flange steel welded joints have been carried out