August 24, 2015 | by Sigmasoft | views 4305
The profitability of a molded rubber product depends to a large extent on the mold efficiency. To achieve the maximum productivity, besides the larges possible number of cavities it is desirable to minimize the rubber consumption and to produce parts without defects.
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Rheology
Rubbers
Automotive
Biomedical
Injection Molding
SIGMASOFT
Newsletters
July 22, 2015 | by Paul Du Bois | views 4290
"Simulation of rubber-like materials is usually based on hyperelasticity. If strain-rate dependency has to be
considered viscous dampers are added to the rheological model. A disadvantage of such a description is timeconsuming
parameter identification associated with the damping constants. In this paper, a tabulated formulation is
presented which allows fast generation of input data based on uniaxial static and dynamic tensile tests at different
strain rates. Unloading, i.e. forming of a hysteresis, can also be modeled easily based on a damage formulation. We
show the theoretical background and algorithmic setup of our model which has been implemented in the explicit
solver LS-DYNA [1]-[3]. Apart from purely numerical examples, the validation of a soft and a hard rubber under
loading and subsequent unloading at different strain rates is shown."
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Mechanical
Rubbers
Hyperelastic
Rate Dependency
Yielding/Failure analysis
Automotive
High Speed Testing
LS-DYNA
Research Papers
March 13, 2019 | by DatapointLabs | views 4289
Multi-scale material models are being increasing applied for high level simulation of complex materials such as UD layups, fabric laminate composites, fiber-filled plastics. These models require data inputs from a variety of material tests which are then assembled into models used in the finite element solvers. We present an infrastructure for the digitalization of such information, where the required material data are collected including a process for maintaining traceability and consistency of the source data. Information about the compositional characteristics and processing history are captured. Built-in software modules or external client tools can be used for calibration of material models with the resulting material file linked to the source data. The accuracy of the reduced order model can be checked by running a validation simulation against a physical test. Models can be published and released into a master CAE materials library output where they can be used to model such materials for a variety of target solvers. This process improves the reliability and accuracy of composites simulation.
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Aerospace and Defense
Automotive
Structural Analysis
Composites
Presentations
Materials Information Management
March 13, 2001 | by DatapointLabs | views 4283
Hyperelastic models are used extensively in the finite element analysis of rubber and elastomers. These models need to be able to describe elastomeric behavior at large deformations and under different modes of deformation. In order to accomplish this daunting task, material models have been presented that can mathematically describe this behavior [1]. There are several in common use today, notably, the Mooney-Rivlin, Ogden and Arruda Boyce. Each of these has advantages that we will discuss in this article. Further, we will examine the applicability of a particular material model for a given modeling situation.
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Rubbers
Foams
Aerospace and Defense
Automotive
Biomedical
Nonlinear Material Models
Structural Analysis
Abaqus
ANSYS
SOLIDWORKS
MSC.MARC
NX Nastran
Research Papers
June 17, 2008 | by Datapoint Newsletters | views 4282
New Tests and TestPaks. New Presentations On-line.
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LS-DYNA
RADIOSS
VISI Flow
Newsletters
Validation
April 13, 2009 | by DatapointLabs | views 4278
We seek to lay down a framework to help us understand the different behavioral classes of foams. Following a methodology that we previously applied to plastics, we will then attempt to propose the right LS-DYNA material models that best capture these behaviours. Guidelines for model selection will be presented as well as best practices for characterization. Limitations of existing material models will be discussed.
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Foams
Automotive
Consumer Products
Material Supplier
Packaging
Home Appliances
High Speed Testing
Nonlinear Material Models
Structural Analysis
LS-DYNA
Abaqus
ANSYS
MSC.DYTRAN
Research Papers
July 27, 2015 | by Paul Du Bois | views 4250
"Recently new materials were introduced to enhance different aspects of automotive safety while minimizing the
weight added to the vehicle. Such foams are no longer isotropic but typically show a preferred strong direction due
to their manufacturing process. Different stress/ strain curves are obtained from material testing in different
directions. A new material model was added to the LS-DYNA code in order to allow a correct numerical simulation
of such materials. Ease-of-use was a primary concern in the development of this user-subroutine: we required stress/
strain curves from material testing to be directly usable as input parameters for the numerical model without
conversion. The user-subroutine is implemented as
MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM, Mat law 142 in LS-DYNA Version 960-1106.
In this paper we summarize the background of the material law and illustrate some applications in the field of
interior head-impact. The obvious advantage of incorporating such detail in the simulation lies in the numerical
assessment of impacts that are slightly offset with respect to the foam’s primary strength direction."
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Mechanical
Foams
Rate Dependency
Automotive
High Speed Testing
LS-DYNA
Research Papers
July 30, 2015 | by Helmut Gese | views 4249
"Today the automotive industry is faced with the demand to build light fuel-efficient vehicles while
optimizing its crashworthiness and stiffness. A wide variety of new metallic and polymeric materials
have been introduced to account for these increased requirements. Numerical analysis can
significantly support this process if the analysis is really predictive. Within the numerical model a
correct characterization of the material behaviour – including elasto-viscoplastic behaviour and failure
- is substantial. The particular behaviour of each material group must be covered by the material
model.
The user material model MF GenYld+CrachFEM allows for a modular combination of
phenomenological models (yield locus, strain hardening, damage evolution, criteria for fracture
initiation) to give an adequate representation of technical materials. This material model can be linked
to LS-DYNA when using the explicit-dynamic time integration scheme.
This paper gives an overview on the material characterization of ultra high strength steels (with focus
on failure prediction), non-reinforced polymers (with focus on anisotropic hardening of polymers), and
structural foams (with focus on compressibility and stress dependent damage evolution) with respect
to crash simulation. It will be shown that a comprehensive material model - including damage and
failure behaviour - enables a predictive simulation without iterative calibration of material parameters.
A testing programme has been done for each material group in order to allow a fitting of the
parameters of the material model first. In a second step different component tests have been carried
out, which were part of a systematic procedure to validate the appropriate predictions of the crash
behaviour with LS-Dyna and user material MF_GenYld+CrachFEM for each material group."
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Mechanical
Plastics
Foams
Metals
Rate Dependency
Yielding/Failure analysis
Automotive
High Speed Testing
LS-DYNA
Research Papers
August 24, 2015 | by Sigmasoft | views 4237
As the demand for functional integration and the need of design differentiation in manufactured products increase, the complexity of plastic parts increases as well; thus some previous knowledge on effective ejection systems becomes insufficient and the challenges in the design of ejection systems grow consistently.
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Rheology
Plastics
Rubbers
Visco-elastic
Automotive
Biomedical
Injection Molding
SIGMASOFT
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