Chickpea (Cicer arietinum L.) is globally cultivated due to its high nutritional value. As with other legumes, its success depends greatly on its inoculation with effective symbiotic rhizobial strains. Since its agricultural importance as an alternative winter crop in Argentina is very recent, there are limited phylogenetic studies on the affiliation and origin of the two strains used for its inoculation here. We attempted to define their specific identity through a multilocus sequence approach on seven housekeeping genes (phylogeny and average nucleotide identity), as well as on the basis of 16S rRNA gene sequence and nodC gene analysis. The strains were accurately and conclusively corroborated as M. ciceri and M. mediterraneum species, and their denominations were found to be associated to originally described chickpea-nodulating strains

Revale, S

Giordano, W

Nievas, F

Foresto, E

Bogino, P

Wisselink, H.H.

University of Twente Research Information

 1.12Contact info:h.h.wisselink@utwente.nlCluster1. Modelling of forming of metal and laminate products, project MC1.05205_4University of Twente, Applied MechanicsP.O. Box 217, 7500 AE Enschede, The NetherlandsH.H. WisselinkForming the limits of damage predictionsFrom fundamentals to application WP4IntroductionDamage and fracture are important criteria in the design of products and processes. In most cases cracks must be avoided. However, some products and processes, rely on the controlled growth of damage and/or cracks in order to obtain a certain functionality or shape. ObjectiveThe objective is to develop tools which allow one to make quantitative predictions of ductile failure in industrially relevant materials and applications. Future work & ValorisationAn effort will be made to tailor the developed techniques to materials and applications put forward by NIMR’s industrial partners.MethodsAn operator split nonlocal ductile damage model, as developed in previous NIMR projects, has been implemented in DiekA and LS-DYNA for 2D and 3D solid elements.For large scale simulations of sheet metal forming processes and crash tests mainly shell elements are used. Details, as shown in Figure 1, cannot be captured with these elements. Therefore the use of cohesive elements, which contain the fracture behavior, together with normal shell elements is studied for these applications.By using a combination of experiments (MC2.05205_1) and detailed simulations of simple bending and tension tests a validated model will be obtained, which predicts the correct moment of fracture and the absorbed fracture energy in simulations with shell elements (Figure 3). Figure 1: Failure of sheet of 1mm thickness in three point bending test with the nonlocal damage model (LS-DYNA).Figure 2: Three point bending test modelled with solid shell elements.Figure 3: An example of a large scale crash simulation (ship collision).Similar global responseDifferent  local behaviour

English

Forming the limits of damage predictions : from fundamentals to application WP4 [poster]

 1.16Contact info:h.h.wisselink@utwente.nlCluster1. Modelling of forming of metal and laminate products, project MC1.05205_4University of Twente, Applied MechanicsP.O. Box 217, 7500 AE Enschede, The NetherlandsH.H. WisselinkForming the limits of damage predictionsFrom fundamentals to application WP4IntroductionDamage and fracture are important criteria in the mechanical design of virtually every product and process. In most cases cracks must be avoided because they compromise the integrity and functionality of the product. Some products and processes, however, also rely on the controlled growth of damage and/or cracks in order to obtain a certain functionality or shape. References[1] J. Mediavilla, “Continuous and discontinuous modelling of ductile fracture”, Ph.D thesis TUE, 2005[2] A.W.A. Konter, J. Broekhuijsen and A.W. Vredeveldt, “A quantitative assesment of the factors contributing to the accuracy of ship collision prediction with FEM”, ICCGS Conference, 2004 ObjectiveThe objective is to develop computational  tools which allow one to make quantitative predictions of ductile damage and fracture in industrially relevant materials and applications. On the one hand, this requires a further development of our physical understanding of ductile failure and the capability to translate this understanding into constitutive models, whereas on the other hand new computational  methods and experimental parameter identification methods need to be developed which enable the application of the theory to problems from the industrial practice. Future work & ValorisationA significant effort will be made to tailor the developed techniques to materials and applications put forward by NIMR’s industrial partners.For example the collision resistance of the side structure, shown in the background, and designed by the Royal Schelde [2] will be investigated.MethodsThe tasks defined for work package 4 aim to make the developments made in the other work packages and in the previous NIMR projects on ductile damage [1] available to the industrial partners. The objective is to enable the industrial use of the developed damage models by their implementation in a commercial Finite Element Method (FEM) package. This objective sets some limitations to the type and implementation of the damage model. The possibilities are being evaluated at the moment. A staggered (or operator-split) approach, in which the (non-local) damage is kept constant during an equilibrium step, seems the most promising option.

Forming the limits of damage predictions; From fundamentals to application. WP4

NARCIS 

Forming the limits of damage predictions, from fundamentals to application

 1.14Contact info:h.h.wisselink@utwente.nlCluster1. Modelling of forming of metal and laminate products, project MC1.05205_4University of Twente, Applied MechanicsP.O. Box 217, 7500 AE Enschede, The NetherlandsH.H. WisselinkForming the limits of damage predictionsFrom fundamentals to application WP4IntroductionDamage and fracture are important criteria in the mechanical design of virtually every product and process. In most cases cracks must be avoided because they compromise the integrity and functionality of the product. Some products and processes, however, also rely on the controlled growth of damage and/or cracks in order to obtain a certain functionality or shape. ObjectiveThe objective is to develop computational  tools which allow one to make quantitative predictions of ductile damage and fracture in industrially relevant materials and applications. This requires a further development of our physical understanding of ductile failure and the capability to translate this understanding into constitutive models. Furthermore experimental parameter identification methods need to be developed (WP1), which enable the application of these models to industrial cases. Future work & ValorisationA significant effort will be made to tailor the developed techniques to materials and applications put forward by NIMR’s industrial partners.MethodsDuctile damage models developed in previous NIMR projects (MC2.98067) will be made available to the partners. A staggered approach, in which the nonlocal damage is kept constant during an equilibrium step has been implemented in DiekA (Figure 1) and is currently being implemented in the commercial FEM code LS-Dyna. Nonlocal models solve the problem of mesh dependency of local models.For large scale simulations of sheet metal forming processes and crash tests mainly shell elements are used. Details like the shear bands shown in Figure 1 cannot be captured with these elements, however the fracture energy should be predicted correctly. The use of a micro structurally based length scale (1-100µm) can become difficult for these kind of simulations as elements sizes (>thickness) should be smaller than the length scale. Figure 1: Damage from simulations of three point bending tests of a sheet of 1mm thickness with the nonlocal damage model showing different failure modes depending on the size of the length scale (l).l=0.0mm (local)l=0.2mml=0.05mm

Foresto, Emiliano

Nievas, Fiorela

Revale, Santiago

Giordano, Walter

Bogino, Pablo

Oxford University Research Archive