I have modelled a crack in a curved shell and I don't quite understand why abaqus shows negative stresses?
I hope it helps you in resolving you issue. Skip to main content. Search form Search. Secondary menu recent posts user list about contact Main menu research education mechanician opinion software industry conference job video.
Create new account Request new password. Navigation Search iMechanica. Writing a paper Writing a proposal in situ Mechanics tensor tensor and its invariants. Tue, - xaisherx I have modelled a crack in a curved shell and I don't quite understand why abaqus shows negative stresses?
Selecting contact output
Several things can be Permalink Submitted by Akumar on Tue, Several things can be going: -ve S22 is actually developing. If you have bending in the model, you can actually get -ve stresses. Negative in the Legend could be just coming from auto limit calculations. If you don't expect -ve S22, then check the elements where it is showing -ve stresses in contour. Contour plot is an artistic representation of field variation to please ignorant viewer. Check abaqus manual for how it is calculated it is very elaborate but quite interesting, you should read it.
Also use Quilt plot. Always trust integration values. These are the actual material point calculations any other are just extrapolation or interpolation. Quick guide Ask iMechanica Having difficulty with posting comments? More comments comments at a glance. Popular content Today's: I share the vision of iMechanica, but am not ready to post anything, should I register?And has since been on a mission to make premium and organic available to the widest possible community.
We strive to maintain our independence by pushing boundaries, challenging conventions and elevating standards. We are committed to organic and plant based and we are passionate about responsibly sourced fresh, wholesome ingredients. At our zero landfill production kitchen powered by renewable energy, we produce small batches of our juice daily and deliver nightly to our retail sites across the Capital, and to a growing network of stockists around the county. And if not - then please get in touch - we drive our innovation with the needs of our customers.
As well as those on a mission to fuel their lifestyles with products and environments which have tangible benefits to their wellbeing. And with sustainability at the heart of our mission, CPRESS is moving away from single-use plastics, in a strategy that is looking to transform our industry. About Us. A drink for your future! Join our Mailing List.Log In. Thank you for helping keep Eng-Tips Forums free from inappropriate posts. The Eng-Tips staff will check this out and take appropriate action.
Click Here to join Eng-Tips and talk with other members! Already a Member? Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free. Register now while it's still free! Already a member? Close this window and log in. Are you an Engineering professional? Join Eng-Tips Forums! Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. First of all, hello to everybody. This is my first post here but I already use this very forum as a source of information : My problem is this the next: I'm doing some basic contact analysis in AbaqusCAE 6.
I have two 3D solids which are in contact 2 planar surfaces. Now I would like to get an equivalent normal force from these result but I don't know how.Log In. This problem will result in a non-linear stress distribution along the bottom edge. Thank you for the confirmation. Red Flag This Post Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.
The Eng-Tips staff will check this out and take appropriate action. Click Here to join Eng-Tips and talk with other members! Already a Member? Join your peers on the Internet's largest technical engineering professional community. It's easy to join and it's free. Register now while it's still free!
Already a member? Close this window and log in. Are you an Engineering professional? Join Eng-Tips Forums! Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. Let take an example of pure sliding between 2 deformable blocks say block A is placed above block Bconsisted of solid elements. The bottom nodes of block A are set to have always the same displacement, so that the bottom elements of block A would have the constant vertical stress.
Does anybody know the reason? Any opinion would be appreciated and thank you for your time in responsing this post. I'm not sure of your fixed displacements but in general if you have two solids in contact then the stiffness at the free edges is not the same as in the centre, hence you'd get a non uniform contact pressure distribution.
The same applies when you look at interference fit between two different lengths of annular rings and you see this effect at the free edge of the shorter ring. I think the contact problem you mentioned is similar to compressing one rectangular block having the bottom edge fully constrained i.
Several of the tooling and casting requirements of a part can be addressed at the design stage. If these requirements are not addressed at the design stage, lot of time is spent in design iteration when the design reaches the die caster. These design issues lead to increase in time and cost of production leading to delay in time to market and reduced profits for the organization.
Download Now. The benefits of cost and time savings using effective collaborative mechanisms at the right time have been highlighted in this white paper. Assembly level constraints need to be satisfied before the design can move downstream. This white paper will go through the various assembly level issues, which need to be tackled by various organizations on a regular basis. Know more about DFMPro, a design for assembly software.In this blog post, we will be discussing about the different methods in modeling bolted connections with Abaqus FEA.
At the last section of the post,we will be showcasing a bolted connection, incorporating a pretensioned bolt. Flanged connections are used extensively in most engineering disciplines. The simplest method for modeling bolts can be seen in Figure 1. In this figure the circular beam profile, corresponding to the bolt shank, is not shown to assist visualization. In the method shown in figure 1, two MPCs have been created, in order to connect each end point of the beam the beam elements represent the bolt's shankto the joint members.
As the control point, each of the beam's end points is first selected. As a slave region to be selected for the MPCs, the user can select a circular area on each of the flange faces or create those partitionscorresponding to the dimensions of the nut,grover or bolt head that fits to the given bolt dimension use metric bolt sizing tables to find this information. The total number of MPCs created should be two one per connection to the each of the flange faces.
The bolt's shank, represented by beam elements with this approach, should have a circular beam profile. As an alternative approach to modeling the bolt shank with this method, connector elements can be used instead of beam elements. This method, does not allow for contact interactions between the bolt's end features such as nuts or headsand the joint members flange faces.
This is shown in Figure 2. In the method shown in figure 2, two planar circular sections have been created and discretized with shell elements. These shells represent the end geometry of a bolt.
The section dimensions of each shell, should correspond to the dimensions of the component modeled e. In this method, the bolt's shank will be modeled by creating a connector of the "bushing" type. This can be done via the Abaqus connector builder, that is quite straight-forward and user friendly. These RPs should then be used in order to create a wire feature, to be subsequently assigned with the connector section.
This connector section should then be assigned with relevant properties, as shown in Figure 2.Use the Abaqus Unified FEA product suite and its multiphysics capabilities to simulate the behavior of soil and other natural materials used in large scale engineering projects. In an Exponentialcontact pressure-overclosure relationship, the surfaces begin to transmit contact pressure once the clearance between them, measured in the contact normal direction, reduces to c0.
At zero overclosure the pressure is zero. The contact modeling capabilities in Abaqus allow access to a library of "surface constitutive models. Abaqus - Introduction Online Training Web - www. So I believe what you see is compressive stresses or contact pressure if you want!! In the Monitor window check that there are no errors or warnings i.
Using the example of a three point bend to show how to define contact between two objects in Abaqus. This allows for a direct comparison of the contact pressure contours, after bolt pretension and after external loading has been applied.
Abaqus integrates noise simulation within the finite element solver, allowing fully coupled structural-acoustic simulations to be performed within familiar Abaqus workflows. As contact pressure grows, true contact area increases and contact conductance grows contact resistance becomes smaller. Adding this soft layer as an elastic continuum will address the problem of the ring being very stiff in shear that causes very high pressure gradients at the edges of contact.
Note that the FEA model always calculates a higher contact pressure than the other methods. Contact definition: using Pressure - Exponential contact and slave surfaces, effectively doubling up the contact definition. Read more here. The behavior in between is exponential. In the data, results, and output database files the output variable CPRESS gives the viscous damping pressures for an open slave node. Surface to surface formulation.
Figure 4 shows the mean contact pressure as a function of the contact strain for all three types of polymer sample. This includes flued-in heads, head-to-shell junctions, expansion joints, thermal stresses, and stresses in components due to loads other than pressure. This variable also gives the contact pressure for a closed slave node.
But when I check the contact pressure I can see negative stresses as well. Value between 0 and 1 suggest partial damage Today, forty years of Abaqus FEA technology remain at the core of an expanded cornucopia of leading multiphysics capabilities. The cavity could be an interior surface on a closed shell-like structure or a "bag". If the overclosure exceedsthe contact state is changed from open to closed, the slave node is 3.
Why does abaqus show negative stresses?
ABSTRACT This report presents the results of an experimental investigation into the contact areas and tire contact pressure distributions produced by statically loaded truck tires. If there are errors, investigate the cause s before resolving ii. For both the 0. For a fully cracked element the value of this variable is 1. It features advanced capabilities for: structural analysis, nonlinear analysis, contact analysis, coupled physics, complex materials, composite analysis, complex assemblies, fracture mechanics and failure analysis.
I have been trying to do this analysis for last 3 weeks. Working with Geometry 3. Ideally it should not give any tensile stresses in the contact pressure? Small negative pressures given As you know, the total pressure in a porous medium at each point is the sum of the elastic stresses from the matrix, and the pore pressure caused by fluid pressurization.
Overview of Contact in Abaqus 1.SIMULIA applications accelerate the process of evaluating the performance, reliability and safety of materials and products before committing to physical prototypes. Application Engineering provides roles for users by industry application and for designers and engineers to utilize simulation throughout their daily product design activities. Simulation technology covers structures, fluids, plastic injection molding, acoustics, and structural applications.
The right capability is delivered in an application context with guided access for occasional users to allow simulation to drive design and power innovation within product teams.
Delivers powerful simulation of structures, fluids, multibody, and electromagnetics scenarios including complex assemblies directly linked with the product data.
Powerful results analytics allows users to use simulation results to inform decision making. With Simulation Analytics, simulation knowledge and its value becomes available for all platform users.
Additive Manufacturing has opened up new possibilities for product design. Our award winning simulation application provides an accurate end-to-end framework with validated predicted capability for distortion, residual stress and micro-structure evolution. Consistent use of realistic simulation, from early concept exploration to virtual compliance validation, is the only way that the resulting engineering challenges can be met.
Upcoming eSeminars Browse all. Quick Links. Product finder. Other Product Families. Contact Sales. Application Engineering Simulation value for product engineers and designers who need application-focused solutions Application Engineering provides roles for users by industry application and for designers and engineers to utilize simulation throughout their daily product design activities.
Industrial Equipment SIMULIA provides realistic simulation solutions that address a multitude of engineering challenges for industrial equipment manufacturers. Life Sciences The SIMULIA product suite contains a wide variety of materials, procedures and load types to simulate the human body, medical equipment and the manner in which the equipment is used.
This includes strength and deformation in large structures and equipment linear and non-linear analysis, the impact of thermal loads, vibrations, fracture and failure, degradation due to corrosion and how fluids, gases and structures interact. Our pre- and postprocessing technology and sophisticated solvers provide a complete and reliable solution for your simulation and structural analysis needs.
Industry Trends. Digital Additive Manufacturing Additive Manufacturing has opened up new possibilities for product design. Customer Stories.