Questions related to Applied Mechanics
The uniaxial (direct) tensile test is not commonly used for masonry structures. Researches mostly rely on bond wrench or bending tests for masonry structures. My questions are:
- What are the main reasons for the direct tensile test being used so little for masonry structures (the brittleness of the material? the low tensile strength? complexity in the boundary conditions, i.e. chances of introducing flexure in the specimen)?
- Are there additional complicating factors with performing direct tensile tests on specimens retrieved from existing structures? Let's say one is able to retrieve a vertical drill core from a masonry structure, what are the additional problems one faces with performing a direct tensile test on such a specimen (compared to a lab made couplet specimen)? Is it perhaps the loaded faces being not completely parallel to each other?
Regular polygons of trigonal and hexagonal symmetry are used as yield criteria in theory of plasticity:
References for regular icositetragon (24-gon) as yield criterion are sought for a systematization of yield and strength criteria.
The beam has a varying cross section. Also one of the sides is loaded uniformly by a force. See attached file for more clarification.
Say that I have 'p' number of variables and 'm' number of constraint equations between these variables. Therefore, I must have 'p - m' independent variables, and the remaining variables can be related to the independent ones through the constraint equations. Is there any rationale for selecting these 'p - m' independent variables from available 'p' variables?
Can an elliptic crack (small enough to remain a single entity, with no internal pressure or shear force) inside an isotropic material (no boundary effect) be expanded in its own plane under externally applied shearing stresses only?
If yes, how did you show that? Do we have experimental evidence for the process?
I am trying to determine the maximum true contact pressure [Cylinder on flat body model]. I only have the Vickers hardness value (500 HV for 10 kgf load). Is there a way to correlate them?
i mean do some thing make abaqus understand that if i put a mass on a point in space , if that point move anywhere mass will also moves with it , that what i mean , if that can done by just put that mass in a datum point for example ??
if i defined mpc link between that point which i defined mass on it , is that mean that mpc link is work with point only and mass together ???
I want to simulate a triboelectric nanogenerator by COMSOL MULTYIPHYSICS.
How to apply mechanical force for contact separation mode?
in tutorial files or articles just sweep the gap between the triboelectric layer for measuring Voc and don't use solid mechanics to apply mechanical force and when I use that facing an error: Failed to find a solution for the initial parameter.
is there any way for direct measurement of the output voltage of TENG in terms of applied forces by COMSOL MULTYIPHYSICS simulating?
I am designing an electrosorption experiment using the 3 electrode system (Working electrode-WE, Counter-CE, and Reference-RE) , and I want to compare the results with OC adsorption. In order to perform an OC experiment, I just need to remove the CE from the potential-stat (still applying the voltage in my solution), am I correct?
Also, for electrosorption, can I apply magnetic stirring? If so what is a good rpm range for it? In cyclic voltammetry (CV) experiment, the electrolyte is kept unstirred to make sure mass transport can occur only by diffusion due to concentration gradients created around the electrode surface. However, this is different so I think applying mechanical mixing by magnetic stirring might enhance the adsorption efficiency of the WE. However, I am not sure what is the good rpm range for it which will not interfere with the electrosorption process.
P.S. I am not an electrochemist, so this might sound silly for the experts.
Hi, I'm working on a mechanical behavior of a new material analytically. For the purpose of verification, I need to obtain stress distribution on the cross section of a curved beam with rectangular cross section. Due to the lack of familiarity with Abaqus, I can't obtain it. How can I find it?
To validate the results of modeling by Abaqus software with experimental results, how can estimate the Chaboche hardening coefficients from the hysteresis curve?
The material is steel.
i am looking for an elasto/mechanochromic material that can undergo color change already at low applied mechanical load. Ideally the color change is reversible upon unloading and color change in visible light spectrum.
No matter if the material is polymer, metal, or ceramic.
I am very thankful for your help or hint.
I am trying to do a static analysis of a torque box using shell elements and I have the following issue.
I have modeled the Boeing 737 wing (torque box) in Autodesk Inventor using surfaces.
Then I transferred it in Ansys Workbench to start the FEA analysis.
However, I want the inner structure of the wing to be made using composite materials.
So, I opened an ACP module. In that module, I cannot hide some surfaces and here's where the problem is.
If I can't hide them, then I cannot select the ribs and apply an Oriented Selection Set.
I tried, also, making three different ACP modules and then assembling them in static structural (transferring shell data) however that results into an error.
I have attached my project file, without the ACP module.
I want to simulate & analyze the fracture and fatigue (crack growth) in the rear axle housing of heavy tracks (Volvo company) in Abaqus.
My question is which method is suitable for this research and how I can find the geometry and the mechanical & fatigue properties for this specific vehicle?
(If there is any related paper/thesis or anyone can help me, please let me know.)
I am dealing with quasi-static compression simulations on topology-optimized lattice structures using the Abaqus Explicit solver.
By the way, I have not modeled material failure model for several reasons and the material model I've used includes Johnson-cook plastic parameters for AM-SS316L. Now here is my question:
How important and effective is modeling material failure in this case? does it effectively change the stress-strain (force-displacement) curves trend?
If yes, what is your suggestion for material failure model of SS316L in Abaqus? Is there any easier way rather than finding J-C damage parameters for SS316L?
It would be great if anyone can help me to find these parameters.
i want to move a parabolically varying load according to time in ansys apdl. this should be written with codes because i want to apply this load for many cycles.
To put this in context, , I am making a Matlab algorithm for topology optimization that consider fatigue breaking. I am basing on the Ole Sigmund algorithm, which discretices the 2D piece into a rectangular mesh.
For analysing the fatigue resistance of a piece candidate (discreticed on little squares), I need the stress tensor everywhere, so I decided to compute the stress on the center of each squared element, with FEA analysis, because displacements of the nodes are already computed .
Then, I apply the standard 4-node quadrilateral element stress analys: I know the 2 displacements (u,v) of each 4 node, and I apply interpolation to know the deformation on the center of the element, and so the 3 stress components. I do it with the B matrix and C matrix:
B=0.5/l*[ -1 0 1 0 1 0 -1 0; 0 -1 0 -1 0 1 0 1; -1 -1 -1 1 1 1 1 -1];
(l=side of the element)
C=(E/(1-nu^2))* [ 1 nu 0;
nu 1 0;
0 0 (1-nu)/2 ];
The problem is that once I compute those stresses, and so the Von Misses stress, the final result doesn't seem to be correct, mostly on parts of the piece being flected.
I also tried taking the 16 closer elements for interpolating the stress on the center of the element, but it didn't work either. I did that last thing with a much bigger B matrix, that has as "input" the 32 displacements of those 16 points around the element:
B=[ -0.0013 0 0.0352 0 -0.0352 0 0.0013 0 -0.0117 0 -0.0117 0 0.0013 0 -0.0352 0 0.0352 0 -0.0013 0 0.0117 0 0.0117 0 -0.3164 0 0.3164 0 0.3164 0 -0.3164 0;
0 -0.0013 0 0.0117 0 0.0117 0 -0.0013 0 0.0352 0 -0.0352 0 0.0013 0 -0.0117 0 -0.0117 0 0.0013 0 -0.0352 0 0.0352 0 -0.3164 0 -0.3164 0 0.3164 0 0.3164;
-0.0013 -0.0013 0.0117 0.0352 0.0117 -0.0352 -0.0013 0.0013 0.0352 -0.0117 -0.0352 -0.0117 0.0013 0.0013 -0.0117 -0.0352 -0.0117 0.0352 0.0013 -0.0013 -0.0352 0.0117 0.0352 0.0117 -0.3164 -0.3164 -0.3164 0.3164 0.3164 0.3164 0.3164 -0.3164 ]/(2*l);
So my question is, what would be the simpliest way to fix this problem, and so to get the correct stress values?
I would prefer a way to fix it using only the 4 nodes around the element, because using 16 makes everything more complicated.
Thanks a lot for your answers.
My attempt to use the drapability and stretching behavior of knitted composites(just fiber without matrix) in die forming. At this moment, I am only interested in the behavior of the fiber.
I ran 2 models (geometrically, constraints and interaction are identical).
Material model used (Steel with plasticity defined).
Results: Are converging. The behavior is as expected.
Job 69- Material model used (Carbon fiber-MAT-1 in .inp and material orientation defined based on texgen software algorithm). Added orientation by calculating the normal for each element using the node data. I have defined the material parameter based upon the property sheet from attached Hexcel-tow data.
The error I get is ratio of deformation speed is too high. I have tried a number of possibility as mentioned in this forum earlier. Any help would be highly appreciated:-)
The simulation involves Rigid body + Polycarbonate Flexible body. The Flexible body penetrates into the rigid body upto some extent and doesn't show up any stress and plastic strains. But when reversed the conditions, i.e. Fix the flexible body and drop rigid body onto it, stress and other results come up, Why does this happens?
I am writing a new plasticity model in Ansys Explicit Dynamics using AUTODYN as solver for Bilinear Isotropic Hardening model but any how unable to add this particular material model code, as I need MATDEF code for above model.
It will be a great help if anyone can help me to write that particular code. So as to define my model and get in continuation with my research.
I want to measure the hardness of particles that are smaller than 120 micrometers. Do you think we can use depth sensing nano indentation method to measure the hardness of this material?
Hello, I am performing an undergraduate finite element analysis research project, and my current task is to find the shear center for an asymmetric C beam. Out of curiosity, how does one go about doing this? (picture of profile attached, I am also just taking a mechanics of materials course at my university as we speak)
I wish you all a wonderful day
There is an open access journal (IJCESA) to call for research paper related to the civil engineering.
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If you are interested, or if you want more information, you can visit our website: https://www.ijcesa.com
We are preparing a material list for a low temperature service (-40 degree C) due to natural gas choking downstream a drain valve. We need to choose the accepted material to suit this application other than ASTM A105. Is there any reference standard which explains the material temperature limitation for low temperature service?
If global warming cannot be resolved by controlling/minimising gas emissions, then extraordinary measures may be the only viable options, one of such ideas is placing a solar shield between the sun and earth at the L1 lagrangian point to obtain a reduction in solar insolation . It may sound crazy, more like science fiction to know that a disk of 2000km in diameter would be necessary to reduce solar radiation reaching earth by 1.7%. I wonder about the sort of stresses that would be experienced by such an enormous body. Also, what sort of materials' properties would be required to withstand the conditions at L1, for example solar radiation, other rays. While it is possible to calculate the disk's orbital velocity around the sun, its angular velocity (around its axis) is difficult to calculate. I would be grateful if those with relevant experience could share their thoughts about how such calculations could be achieved.
The toughness and resilience are calculated when tensile load is applied. Will a material absorb same energy when a impact load is applied such as bullet fired on the material front face? Which material will absorb more energy; whose resilient modulus is more or whose toughness modulus is more or a material which becomes strain hardened?
I have a Scenario where my lock nut is tightend using a prevailing torque of 14 Nm (as mentioned by the manufacturer) on to the rotor placed between bearings (But the tightening direction and the rotor rotating direction is same unfortunately). The lock nut is loosened after particular life cycle of usage as the rotor rotates with a acceleration of 1230 rad/sec and every time it starts, the sudden acceleration loosens the lock nut. Is there a simple approch to calculate a appropriate prevailing torque for this situation, so that the lock nut does not loosen up when the rotor starts accelerating towards it's max RPM of 9400 in 1 second?
This question requires explanation. Discussion on the second day of Galileo’s Two Chief World Systems raises the point.
Simplicio, taking the position of those opposed to Copernicus, doubts the Earth moves; if Earth moved it would have to move at too great a speed. Sagredo and Salviati say this objection has no merit. The fixed stars have a radius far greater than the Earth, and yet the implied speed, much greater than that of the Earth in the Copernican conceptual reference frame, does not undermine the belief of the anti-Copernicans in their objection. Here is an inconsistency.
The inconsistency is not encountered in modern times that takes for granted the heliocentric model of the solar system. This argument, based on the large radius of the distant stars, is one not usually encountered. One supposes that is so, because it is unnecessary. But then the question arises. Does society lose or forget these old insights that are discarded once new conceptual reference frames take hold? Or, perhaps, is nothing lost?
I'm using abaqus dynamic implicit solver to analyze hip joint. There is not problem like this with static step. but i have to use time depended loads. so when i use dynamic implicit; there are stresses only in force applied area but no stress or displacement in anywhere else. i also tried with dynamic explicit step and concentrated and pressure loads but the problem didnt solve.
i've used frictionless surface to surface contact and fixed a region far from load applied area. and material properties defined by mimics software.
i'll also add a photo and abaqus files fore details. thanks alot for your help.
A simple crack system (Figure 1) can be readily studied to estimate the Hertzian conoidal crack angle and length, and also the stress intensity factor.
This is a 3-D brittle elastic half-space on the flat boundary Ox1x3 of which a rectilinear contact pressure along Ox3 is exerted by a cylinder whose axis is parallel to x3; the cylinder lies along Ox3 on the flat boundary. A planar straight-front crack inclined by an angle θ with respect to x1x3 is present under the action of the load along x2 due to the cylinder. The relevance of this modelling may be understood as follows. A slab of cylinder with thickness dx3 at spatial position O’ (0, 0, x3) exerts elastic fields (displacement and stress) proportional to those of a point load at O’ (proportionality coefficient dx3). Physically, this corresponds to the action of a spherical indenter to which is associated a conoidal fracture surface for sufficiently large load (Roesler (1956) as quoted by Frank and Lawn (1967)). The coalescence of conoidal cracks from different slabs of cylinder along Ox3 would produce planar fracture surface envelops parallel to x3 at large crack lengths. Therefore, we expect the modelling in Figure 1 to provide the experimentally observed fracture surface inclination angle θ and crack length l as a function of critical load P by both a spherical indenter and cylinder. This is the essence of the modelling depicted schematically in Figure 1.
What is the tensor type for Green Lagrange strain tensor and 2nd 2nd piola kirchhoff tensor?
Stress and strain are called 2nd order tensor because they follow the transformation rule: sigma`= R * sigma * R' where R is transformation matrix.
Deformation gradient, rotation matrix and 1st piola kirchhoff are called two point tensor because they relate two configuration. For example deformation gradient is: F(iJ) = xi * XJ where * is dyadic or tensor product and XJ and xi are the element before and after deformation.
What about Green Lagrange strain tensor and 2nd piola kirchhoff tensor?
which they do not change with element rotation
Using damage model includes the relation between the effective and true stress. The true stress-strain curve is the stress-strain curve measured directly from experimental tests which could include softening part. While the effective stress-strain shouldn't have. Is that right?
I am trying to model the strain-softening behavior of rock mass using UMAT subroutine. And, I am applying the 'static Riks method'. My model is running fine in abaqus under small loading. However, when comparatively large loading is applied the analysis is being aborted after 18% load application with an error msg, 'THE SOLUTION APPEARS TO BE DIVERGING. CONVERGENCE IS JUDGED UNLIKELY'.
I have checked the .msg file, .log file and the UMAT subroutine file, but could not find any thing helpful.
Kindly give me some suggestions for solving this problem.
For close shaped section, polar moment of inertia can be calculated from perpendicular axis theorem (adding both the 2nd moment of area in cross sectional axis). But how to calculate polar moment of inertia (2nd moment of area in perpendicular direction of the cross section) of I beam?
For an ndof vibration system of mass and dampers, we know the equation of motion for imposed force.
but in finite element codes, it is also possible to apply a constant displacement and calculate the reaction force in the fixed end of the system as the response function .
Anyone could help with how to write the equation of motion for such a vibrating system ?
It's seems that addition of carbon atoms increase the hardness by solid solution strengthening. However I do not know why it will have more effect on ferrite than on Austenite.
I encountered a return-map technique in many papers but I do not understand how it works.
I am modelling the heat transfer analysis of a wire electrode during the wire EDM process in ABAQUS. Can anyone please help how to apply the wire pre tension in the model as a boundary condition. Do I need to use coupled temperature displacement analysis to apply this mechanical constraint. I am attaching my model of wire electrode.
Thank you in advance.
I don´t have any idea about these two add on softwares for fatigue calculation. I am also new in FE simulation. Any comments or suggestions about the operating of these two softwares.
The beam has unsymmetrical section and is simply supported at its both ends and subjected to forces and moments in all 3 directions at a point.
I am working on cohesive contact(Between two Aluminium bars). I just have some questions that I am wondering if anyone can help me by answering them.
1. How can I find the the parameters in traction-separation: Knn, Kss, Ktt ( should I consider module of shear and elasticity for them?)
- In damage initiation: normal, shear 1, shear 2 (would I consider tensile and shear strength for these values?)
- In damage evolution: fracture energy. mix-mode ratio 1 and 2
2. From where i can get this parameters ??
I'm looking forward to hearing from you soon.
The function assumes a direct and reverse law. What do we know about the inverse function? Never mind. This is just the shadow of the direct function. Why don't we use the inverse function, as well as direct? ------------- I propose the concept of an unrelated function as extended concept of reverse function. ------------ There is a sum of intervals, on each of which the function is reversible (strictly monotonic) -nondegenerate function. ---------- For any sum of intervals, there is an interval where the function is an irreversible-degenerate function.
It seems that when an element (let's say an infinitesimal 3D cube) on earth is not subject to applied forces, the assumed stresses in all dimensions are zero. Why don't we take the atmospheric pressure into account?
In the case of a material whose strength is dependant on the confining pressure, will ignoring atmospheric pressure give a false indication of its actual strength?
There are control strategies like LQR, Positionfeedback control, Negative velocity feedback control, etc.
Which one will provide better active control of vibration ?
Normally, representative volume element (RVE) of the composite is independent of geometry. There are several homogenization methods available that defines regular shaped like rectangular, quadrilateral with inclusions of rectangular,circular,ellipsoidal, spherical shapes. Is there any analytical methods defined for irregular shaped RVE?
The strain energy of Abaqus neo-Hookean material is:
U = C10 * ( Ibar1 - 3 ) + ( 1 / D1 ) * ( Jel - 1 ) ^ 2
If D1 = 0, then stress values will become infinite. But, there are examples in Abaqus Documentation that D1 is assumed to be zero.
What happens when D1 is set to be zero in Abaqus neo-Hookean material?
Does it change the strain energy function to avoid infinite stress?
What does it mean when D1 is zero?
I am doing quasi static and high strain rate compression and tension test but the yield value are different. Compression yield is grater than tensile yield. What is the reason behind it.
Eigenstrain reconstruction of residual strains in an additively manufactured and shot peened nickel superalloy compressor blade
E Salvati, AJG Lunt, S Ying, T Sui, HJ Zhang, C Heason, G Baxter, ...
Computer Methods in Applied Mechanics and Engineering 320, 335-351
Stress fracture is associated with significant morbidity, attrition, failure to complete training, failure to return to pre-injury level activity as well as increased likelihood of re-injury, specifically within military populations. Pathogenesis of stress fracture is multifactorial in nature. The incremental rate of progression in both volume and intensity of high impact physical activity leading to a breach the bones capacity to tolerate repetitively applied mechanical loading such that repair is exceeded by damage, however, the precise mechanisms are yet to be confirmed.
Stress fractures require some of the longest recovery times and is reported to range from three weeks to several months. The Professional, legal and moral responsibility to investigate causation, management and mitigation of these costly injuries are the property of both organisation and individual clinician.
Our stress fracture protocol consist of 4-6 weeks partial weight bearing, once pain subside, commence 3 phases Rehab programme. Therefore, I am inviting your opinion regarding effective stress fracture rehabilitation method to prevention as well as intervention to enhance bone healing process.
Please, let me know, what the theoretical predicaments and obstacles are in analysis of nonlinear pendulum dynamics. Please cite some references and texts on that. Thank you.
In Abaqus I have an axisymmetric model of the rotor for a steel seal with a thin ceramic face. I want to get the circumferential stress induced by friction on the rotor face, when the seal is spinning at steady state, to determine interfacial stresses between the main body of the seal and the film. I see that this can be done in Abaqus, but I can't seem to find a way to specify spinning along the correct axis of rotation.
In case of plane stress and plane strain , the biharmonic equation roots will be different as the Hooke's law is different for both the cases. So, I would like to ask can we use same complex potential function (identical in form) for both the cases , which eventually will be different and produce distinct stress / displacement field .
We are studying the effect of combine (Shear and tension) loading on failure of Metallic structure (Aluminum and mild Steel). We observed that failure strain in Pure shear is higher than the Pure Tension loading. Though stress developed in the Pure tension loading is higher than the Pure shear loading. I do not able to understand the proper reason behind this.
Hi all, I have a bike that has top speed at 70 kmph in 5th gear, 4000 rpm. I feel like there is still more engine power left un-utilized. Now i wish to do some calc and add a 6th gear, so that top speed is pushed to 100 kmph. Please shed some light on this topic and help me do math and identify if its feasible or not.
Which theory is used to calculate shear stress in Ansys workbench?
because I like to determine shear stress for a brittle material through Ansys.
Dear all researchers,
I observed that Fracture Strain and Fracture Toughness of Aluminum Alloys depends upon the strain rate, as we increase the stain rate Fracture Strain and Fracture Toughness also increases. I don't able to find the reason behind this.
I know that at low strain rates the flow stress increases with increase in
strain rate. At higher strain rates it still increases but at a slower rate because of the softening effect due to temperature rise in the material. But what is the philosophy behind this. why dose flow stress increase with increase in strain rate.
My name is Linto George Thomas. I completed my master of technology in manufacturing engineering , from Manipal University, India.
I have a curious mind with great inquisitiveness to study for a doctoral program in the area of bio-composites.
Let me know the criteria's and procedures for approaching a supervisor and if anyone have opportunities please let me know.
In the NZSEE the follow equations are given for the in-plane capacity of a masonry wall, whenever rocking occurs:
Vr = (0,9 (α · P + 0,5Pw)Lw)/Heff
While the following equations are given for the toe-crushing capacity:
Vr = ((α · P + 0,5Pw)Lw)/Heff) · (1-(fa/0,7f'm))
- α = factor for boundary conditions (0,5 fixed-free; 1,0 fixed-fixed);
- P = vertical load acting on top of wall;
- Pw = Own weight of the wall;
- Lw = length of the wall;
- Heff = effective height of the wall.
- Could anyone explain to me why the own weight (Pw) is multiplied by a factor 0,5 in both formulas?
- And could anyone explain to me why α = 0,5 for fixed-free walls?
Are there current research results (maximum 10 years) that have successfully developed a sandwich made of low-cost materials that are environmentally friendly?
I hardly find anything on the internet.
Thank you very Much