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A phononic band gap model for long bridges. The ‘Brabau’ bridge case

Submitted by Giorgio Carta on

In this paper, we study the dynamic flexural behaviour of a long bridge, modelled as an infinite periodic structure. The analysis is applied to the ‘Brabau’ bridge across the river Tirso in Italy. The approach reduces to a spectral problem leading to the analytical expression of the dispersion relation, which provides the ranges of frequencies for which waves do and do not propagate. The contributions of the bridge structural elements on the dispersive properties of the structure are investigated in detail.

Abaqus VUMAT for hypoplastic law

Submitted by ferial on
Please, I’m investing about the hypoplastic model for granular materials to study the behavior of sand under a dynamic excitation. I try to use the UMAT – VUMAT interface, Interface between UMAT (Abaqus/Standard) and VUMAT (Abaqus/Explicit) from http://www.soilmodels.info/ node17.html website.

Shape formation of helical ribbons induced by material anisotropy

Submitted by zichen on

Helices are ubiquitous building blocks in natural and engineered systems. Previous studies showed that helical ribbon morphology can result from anisotropic driving forces and geometric misorientation between the principal axes of the driving forces and the geometric axes. However, helical ribbon shapes induced by elastic modulus anisotropy have not been systematically examined even though most natural and engineered structures are made of composite materials with anisotropic mechanical properties.

cohesive model of Needleman was input into abaqus, but wrong???

Submitted by yiqinuli on
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 I have written  vumat codes of a cohesive model of Needleman (whose paper entilted "Numerical simulations of fast crack growth in brittle solids"), and I have implemented it into ABAQUS/Explicit, but the predicted result is wrong. I don't know why. The corresponding fortran file is as follows:

      subroutine vumat(

C Read only (unmodifiable)variables -

     1  nblock, ndir, nshr, nstatev, nfieldv, nprops, lanneal,

     2  stepTime, totalTime, dt, cmname, coordMp, charLength,

Ballistic impact simulation of composite targets in AUTODYN?

Submitted by aswani006 on

In general we use Johnson-Cook model for bullet, which accounts for strain-rate effects, while for the target (Composites), the we use orthotropic constitutive model. Does it mean that strain-rate effects are not important for composites? The Johnson-Cook model cannot be readily used for composites. How does the AUTODYN considers strain rate effects for composites in ballistic impact simulations? 

UMAT for Kinematic hardening

Submitted by Qusay on
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I just followed the code that ABAQUS presented (Copied below), but I'm getting very strange results comparing with ABAQUS GUI, what's wrong with that? 


Please help if you have experience 

 

 


      SUBROUTINE UMAT(STRESS, STATEV, DDSDDE, SSE, SPD, SCD, RPL,

     1 DDSDDT, DRPLDE, DRPLDT, STRAN, DSTRAN, TIME, DTIME, TEMP, DTEMP,

     2 PREDEF, DPRED, CMNAME, NDI, NSHR, NTENS, NSTATV, PROPS, NPROPS,

Idealized vs. Realistic Microstructures: An Atomistic Simulation Case Study on γ/γ′ Microstructures

Submitted by Erik Bitzek on

Maybe the following open access article in Materials  201710(1), 88 is of interest to modellers wanting to use experimental microstructures in their simulations:

http://www.mdpi.com/1996-1944/10/1/88