Phase-field modelling of fracture in single crystal plasticity

We propose a phase-field model for ductile fracture in a single crystal within the kinematically linear regime, by combining the theory of single crystal plasticity as formulated in Gurtin et al. (2010) and the phase-field formulation for ductile fracture proposed by Ambati et al. (2015) . The model introduces coupling between plasticity and fracture through the dependency of the so-called degradation function from a scalar global measure of the accumulated plastic strain on all slip systems. A viscous regularization is introduced both in the treatment of plasticity and in the phase-field evolution equation. Testing of the model on two examples for face centred cubic single crystals indicates that fracture is predicted to initiate and develop in the regions of the maximum accumulated plastic strain, which is in agreement with phenomenological observations. A rotation of the crystallographic unit cell is shown to affect the test results in terms of failure pattern and corresponding global and local response

A segmentation-free isogeometric extended mortar contact method

This paper presents a new isogeometric mortar contact formulation based on an extended finite element interpolation to capture physical pressure discontinuities at the contact boundary. The so called two-half-pass algorithm is employed, which leads to an unbiased formulation and, when applied to the mortar setting, has the additional advantage that the mortar coupling term is no longer present in the contact forces. As a result, the computationally expensive segmentation at overlapping master-slave element boundaries, usually required in mortar methods (although often simplified with loss of accuracy), is not needed from the outset. For the numerical integration of general contact problems, the so-called refined boundary quadrature is employed, which is based on adaptive partitioning of contact elements along the contact boundary. The contact patch test shows that the proposed formulation passes the test without using either segmentation or refined boundary quadrature. Several numerical examples are presented to demonstrate the robustness and accuracy of the proposed formulation.Comment: In this version, we have removed the patch test comparison with the classical mortar method and removed corresponding statements. They will be studied in further detail in future work, so that the focus is now entirely on the new IGA mortar formulatio

Analysis of VvMybA1 and VvMybA2 genes in grape bud sports

Berry skin colour is a fundamental qualitative trait of grape varieties, which has become largely diversified during the centuries of viticulture. Colour mutations in grape berry, resulting in black, red, pink, grey, green and yellow fruits, were relatively frequent events. In the Carpathian Basin there are several berry colour variant groups named conculta, members of which contain bud sports differing in skin colour. In most cases, this difference cannot be detected by microsatellite analysis, therefore we examined the variations of the VvMybA1 and VvMybA2 genes related to anthocyanin biosynthesis. Based on the results of the allelic polymorphisms, we have discriminated the conculta members among the old Hungarian and several other foreign varieties. Based on our results, it was possible to find molecular differences in 10 out of 14 concultas

Evidence for a Sympatric Origin of Ribolla gialla, Gouais Blanc and Schiava cultivars (V. vinifera L.)

Ribolla gialla is an autochthonous grape variety cultivated in Friuli Venezia Giulia (Italy) and in Slovenia,and probably originated in Eastern Central Europe. Just like Ribolla gialla, the Gouais blanc and Schiavacultivars also appear to have originated in the same geographical area. To verify this hypothesis, a poolof varieties probably sharing the same historical and geographical origin were taken into account. Thefingerprinting, by 35 SSR loci, of Gouais blanc, Ribolla gialla, Schiava grossa and Schiava lombarda(synonyms of Schiava bresciana), is presented and the correlation among historical, geographical andgenetic information of these cultivars was investigated. Gouais blanc and Traminer, already suggested askey varieties in the development of European grape diversity and as parents for some French varieties,interestingly enough seems to be linked to Ribolla gialla. The putative parentage was verified using 58microsatellite markers. The genetic results suggest a common geographical origin for Gouais blanc,Ribolla gialla and the Schiava group: these cultivars appear to be related through sympatric origin. Thehypothesis of Ribolla gialla as a progeny of Gouais blanc and Traminer was ruled out. The data proved asecond-degree relationship between Gouais blanc and Ribolla gialla and a third or more distant degree ofrelationships between Ribolla gialla and Traminer

Vitis vinifera subsp. sylvestris and sativa; so far, so close: a 20 SSR based comparison of the two taxa

In Vitis vinifera L., the hypothesis of secondary domestication center, located along the wild progenitor distribution areas, is suggestive and credible even if up to now close parentage relationships between domestic (Vitis vinifera L. subsp. sativa (DC.) Hegi) and wild (Vitis vinifera L. subsp. sylvestris (Gmel.) Hegi) grapevines have not been detected, possibly due to century long separation of the two subspecies. The aim of this work was to verify the possibility of tracing a flow between the two compartments basing on molecular data and thanks to the availability of a huge dataset comprising 645 wild and more than 1400 cultivated samples. Twenty SSR loci were used to describe and genotype both sylvestris and sativa compartments. The sylvestris samples were all collected in the frame of a three year census in Italy and are representative of the Italian distribution range from north to south. The cultivated sativa accessions mainly (1231 samples) belong to the Vassal (INRA-Montpellier) collection, while the remaining (200) were selected in the frame of the Italian grapevine germplasm. Results highlighted a high level of genetic diversity for both wild and cultivated groups. STRUCTURE analysis clearly evidenced the separation of the two compartments and no first or second degree relationships were evidenced between the two subspecies

Vitis vinifera subsp. sylvestris and sativa; so far, so close: a 20 SSR based comparison of the two taxa

In Vitis vinifera L., the hypothesis of secondary domestication center, located along the wild progenitor distribution areas, is suggestive and credible even if up to now close parentage relationships between domestic (Vitis vinifera L. subsp. sativa (DC.) Hegi) and wild (Vitis vinifera L. subsp. sylvestris (Gmel.) Hegi) grapevines have not been detected, possibly due to century long separation of the two subspecies. The aim of this work was to verify the possibility of tracing a flow between the two compartments basing on molecular data and thanks to the availability of a huge dataset comprising 645 wild and more than 1400 cultivated samples. Twenty SSR loci were used to describe and genotype both sylvestris and sativa compartments. The sylvestris samples were all collected in the frame of a three year census in Italy and are representative of the Italian distribution range from north to south. The cultivated sativa accessions mainly (1231 samples) belong to the Vassal (INRA-Montpellier) collection, while the remaining (200) were selected in the frame of the Italian grapevine germplasm. Results highlighted a high level of genetic diversity for both wild and cultivated groups. STRUCTURE analysis clearly evidenced the separation of the two compartments and no first or second degree relationships were evidenced between the two subspecies

Detection of grapevine synonyms in Lombardy and Piedmont regions (northern Italy)

The Italian viticulture is characterized by a high number of autochthonous varieties (about 1700), some of them renowned throughout the Country, some other only of local importance. Nevertheless, the real estimation of this biodiversity is made difficult due to the great amount of synonyms, homonyms and misnomers. The aim of this work was to undertake a comparison for varietal identity of minor, lesser cultivars in two field collections of neighboring regions (Lombardy and Piedmont) located in northern Italy, verifying synonyms in different areas. Forty-seven accessions were described by morphological (OIV descriptors) and genetic (microsatellites) characteristics. Thirty-eight varieties were identified belonging to three categories: varieties of great importance in Italy and locally misnamed, varieties important in the region of Piedmont and misnamed in Lombardy, and currently minor grapes but of historical significance in both Piedmont and Lombardy regions

Detection of grapevine synonyms in Lombardy and Piedmont regions (northern Italy)

The Italian viticulture is characterized by a high number of autochthonous varieties (about 1700), some of them renowned throughout the Country, some other only of local importance. Nevertheless, the real estimation of this biodiversity is made difficult due to the great amount of synonyms, homonyms and misnomers. The aim of this work was to undertake a comparison for varietal identity of minor, lesser cultivars in two field collections of neighboring regions (Lombardy and Piedmont) located in northern Italy, verifying synonyms in different areas. Forty-seven accessions were described by morphological (OIV descriptors) and genetic (microsatellites) characteristics. Thirty-eight varieties were identified belonging to three categories: varieties of great importance in Italy and locally misnamed, varieties important in the region of Piedmont and misnamed in Lombardy, and currently minor grapes but of historical significance in both Piedmont and Lombardy regions