Hello,
I have a question regarding viscoelastic materials and property definitions through prony series.
If i am not wrong ,the values wi and τi of the series can be expressed either in terms of time domain or frequency domain.
Having the prony series expressed at time domain, how can the relaxation tensor be expressed? Do i still need to perform
Laplace-Carson transformation, of the time dependent relaxation and creep functions or their prony series expression is enough,
so i can get the full relaxation tensor (isotropic case) as:
G(t) = G0(1-Σν1 (wi*(1-exp(-t/τi))) (similarly for K(t))
and the full tensor: Gijkl(t) = 2G(t)Idev +K(t)1⊗1
Idev = deviatoric of fourth order unit tensor
1 = second order unit tensor
⊗ = tensor product
Thank you in advance.
Post-Doc Position: Multiscale Simulations of Pattern Formation in Mixed Crystals
The chair of Materials and Process Simulation at the University of Bayreuth is offering a postdoc position in the field of multiscale simulations of advanced materials. In the project, a combination of classical Monte Carlo simulations and ab initio calculations is used for investigating the formation of domains in half-Heusler materials. The investigations are of great relevance for the development of new thermoelectric materials. The project is funded within the framework of the focus program SPP 1386 “Nanostructured Thermoelectrics” by the German Research Foundation (Deutsche Forschungsgemeinschaft).
Are you interested in broadening your scientific knowledge by supporting the development of novel alternative energy sources with the help of state-of-the-art multiscale simulation techniques? Have you completed your masters/diploma degree and your PhD (doctoral degree) with above-average results?
In this case, we offer you a stimulating environment in the field of computer aided materials design, implemented in a top-level research framework. We are a dynamic, international team of multidisciplinary scientists, engaged in numerous science and industrial cooperations. In our scientific work, we cover the whole spectrum from basic concepts of physical modeling over implementation with enhanced supercomputing techniques to industrially relevant questions of simulation-based material design. This involves developing, implementing, and applying models at different scales, such as ab initio, molecular, phase-field, and FEM models.
Applicants must hold a doctor/PhD degree and have the documented ability to carry out novel research projects. They should have gained fundamental experience in modeling and simulation in physics, chemistry, mathematics, or material science. We appreciate candidates with good skills in, at least, one of the following topics: Monte Carlo simulations, ab initio density functional theory or statistical physics. We especially encourage applications of young scientists who just recently accomplished their PhD.
We offer:
A postdoc position (TV-L E13)
The University of Bayreuth supports women in science and especially encourages them to apply. Handicapped applicants will be preferred if they are equally qualified.
Please submit your application, as soon as possible, to:
Prof. Dr.-Ing. Heike Emmerich
Chair for Material- and Process Simulations (MPS)
University of Bayreuth
Postal address: MPS, Postfach 10 12 51, D-95440 Bayreuth
Visitor address: Universitätsstraße 30, Gebäude NW III, D-95447 Bayreuth
Email: sekretariat-mps@uni-bayreuth.de
_______________________________________________________________________________________
For any further details:
Dr. Thomas Gruhn , thomas.gruhn@uni-bayreuth.de
Post-Doc Position: Multiscale Simulations of Pattern Formation in Mixed Crystals
The chair of Materials and Process Simulation at the University of Bayreuth is offering a postdoc position in the field of multiscale simulations of advanced materials. In the project, a combination of classical Monte Carlo simulations and ab initio calculations is used for investigating the formation of domains in half-Heusler materials. The investigations are of great relevance for the development of new thermoelectric materials. The project is funded within the framework of the focus program SPP 1386 “Nanostructured
Thermoelectrics” by the German Research Foundation (Deutsche
Forschungsgemeinschaft).
Are you interested in broadening your scientific knowledge by supporting the development of novel alternative energy sources with the help of state-of-the-art multiscale simulation techniques? Have you completed your masters/diploma degree and your PhD (doctoral degree) with above-average results? In this case, we offer you a stimulating environment in the field of computer aided materials design, implemented in a top-level research framework. We are a dynamic, international team of multidisciplinary scientists, engaged in numerous science and industrial cooperations. In our scientific work, we cover the whole spectrum from basic concepts of physical modeling over implementation with enhanced supercomputing techniques to industrially relevant questions of simulation-based material design. This involves developing,
implementing, and applying models at different scales, such as ab
initio, molecular, phase-field, and FEM models.
Applicants must hold a doctor/PhD degree and have the documented ability to carry out novel research projects. They should have gained fundamental experience in modeling and simulation in physics, chemistry, mathematics, or material science. We appreciate candidates with good skills in, at least, one of the following topics: Monte Carlo simulations, ab initio density functional theory or statistical physics. We especially encourage applications of young scientists who just recently accomplished their PhD.
We offer:
A postdoc position (TV-L E13)
The University of Bayreuth supports women in science and
especially encourages them to apply. Handicapped applicants will be
preferred if they are equally qualified.
Please submit your application, as soon as possible, to:
Prof. Dr.-Ing. Heike Emmerich
Chair for Material- and Process Simulations (MPS)
University of Bayreuth
Postal address: MPS, Postfach 10 12 51, D-95440 Bayreuth
Visitor address: Universitätsstraße 30, Gebäude NW III, D-95447 Bayreuth
Email: sekretariat-mps@uni-bayreuth.de
_______________________________________________________________________________________
For any further details:
Dr. Thomas Gruhn , thomas.gruhn@uni-bayreuth.de
Post-Doc Position: Multiscale Simulations of Pattern Formation in Mixed Crystals
The chair of Materials and Process Simulation at the University of Bayreuth is offering a postdoc position in the field of multiscale simulations of advanced materials. In the project, a combination of classical Monte Carlo simulations and ab initio calculations is used for investigating the formation of domains in half-Heusler materials. The investigations are of great relevance for the development of new thermoelectric materials. The project is funded within the framework of the focus program SPP 1386 “Nanostructured Thermoelectrics” by the German Research Foundation (Deutsche Forschungsgemeinschaft).
Are you interested in broadening your scientific knowledge by supporting the development of novel alternative energy sources with the help of state-of-the-art multiscale simulation techniques? Have you completed your masters/diploma degree and your PhD (doctoral degree) with above-average results?
In this case, we offer you a stimulating environment in the field of computer aided materials design, implemented in a top-level research framework. We are a dynamic, international team of multidisciplinary scientists, engaged in numerous science and industrial cooperations. In our scientific work, we cover the whole spectrum from basic concepts of physical modeling over implementation with enhanced supercomputing techniques to industrially relevant questions of simulation-based material design. This involves developing, implementing, and applying models at different scales, such as ab initio, molecular, phase-field, and FEM models.
Applicants must hold a doctor/PhD degree and have the documented ability to carry out novel research projects. They should have gained fundamental experience in modeling and simulation in physics, chemistry, mathematics, or material science. We appreciate candidates with good skills in, at least, one of the following topics: Monte Carlo simulations, ab initio density functional theory or statistical physics. We especially encourage applications of young scientists who just recently accomplished their PhD.
We offer:
A postdoc position (TV-L E13)
The University of Bayreuth supports women in science and especially encourages them to apply. Handicapped applicants will be preferred if they are equally qualified.
Please submit your application, as soon as possible, to:
Prof. Dr.-Ing. Heike Emmerich
Chair for Material- and Process Simulations (MPS)
University of Bayreuth
Postal address: MPS, Postfach 10 12 51, D-95440 Bayreuth
Visitor address: Universitätsstraße 30, Gebäude NW III, D-95447 Bayreuth
Email: sekretariat-mps@uni-bayreuth.de
_______________________________________________________________________________________
For any further details:
Dr. Thomas Gruhn , thomas.gruhn@uni-bayreuth.de
Hi, we're trying to model with ABAQUS a reinforced concrete beam under a rolling load. We want to investigate the compressive low cycle fatigue of reinforced concrete elements under a variable bending moment. We are using a Static Step (total step time: 18000 sec) and a concentrated force applied on the middle cross section with the following load history*:
0 0
1 0.048715313
2 0.115621788
3 0.19938335
4 0.299177801
5 0.413874615
6 0.542343268
7 0.683556012
8 0.836485098
9 1
10 0.864850976
11 0.738129496
12 0.618910586
13 0.505960946
14 0.398355601
15 0.295066804
16 0.194964029
17 0.096916752
18 0
*obviously, in order to represent a loading time of at least 10^3 cycles, this load history is repeated several times.
We modeled the concrete (class C20/25) with the "Concrete Damaged Plasticity" behaviour, using the following parameters:
Dilation angle: 36.31°
Eccentricity: 0.01
fb0/fc0: 1.16
K: 0.66667
Viscosity parameter: 0.002
CONCRETE COMPRESSION DAMAGE
STRESS INEL. STRAIN DAMAGE PARAMETER
8.4 0 0
11.311 7.5E-005 0
16.801 9.9E-005 0
22.87 0.000154 0
28.004 0.000761 0
22.532 0.002558 0.193
11.332 0.005675 0.596
2.9442 0.0117331 0.897
CONCRETE TENSION DAMAGE
STRESS CRACK. STRAIN DAMAGE PARAMETER
1.864 0 0
2.65 3.3E-005 0
1.744 0.00016 0.406
0.805 0.00028 0.696
0.211 0.000665 0.92
0.053 0.001087 0.98
The beam was modeled with a 2D shell having 2 rebar layers representing the steel reinforcement (we think that's a good approximation, since this is a two-dimensional problem).
The reinforcements were modeled with an elasto - plastic behaviour, also including a kinematic hardening.
Our questions are:
1) Is better to create a Static Step (with a cyclic load history) or a Dyrect Cyclic Step to represent the variable load?
2) Are the parameters used to model the concrete behaviour good?
3) In case that the answer to the second question is "NO", do you have any suggestions?
THANKS
Dear All,
I decided to put this post since I am trying to model piles on granular materials with Abaqus and I am having LOADS of problems, some of them due to my lack of understanding in the subject and others becasue there is not enough information around. Some of my problems are:
1- convergence problems: I am using Mohr coulomb for the soil and elasticity for the pile. If the difference between Young's modulus for both materials is to big it does not converge on Abaqus Static. If I do not put a bit of cohesion in my soil it also does not converge.
2- Different failure mode or smaller than it should be.
I have done a few 2D simulations and the results I get from Abaqus are completely different than the results of the close form solution, even if I refine the mesh.
I decided to start with shallow foundations in 2D and, once again, the above happens. I am using the default solver parameters, NLgeom on, cohesion of 2kPa, friction angle of 42 degrees (dense sand), dilation of 20degrees and E=100MPa and the same Poisson's coefficient=0.3
The elements I am using are the C3D8R for the 3D and the CPE4R for the 2D simulations. In order to get the displacement load curve I am displacing the pile or the shallow foundation, vertically, using the boundary condition option.
Any expertise is extremely welcome.
Regards
Pedro