Questions tagged [modeling]
Use this tag for questions about numerical or analytical modeling and simulation of engineered systems.
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FEA: Newton-Raphson algorithm for Dirichlet BC non-linear static analysis
I have a standard non-linear static problem to solve with FEA. I am applying displacement boundary conditions only, no external force. The equation to solve look like these:
$K(u)u=R(u)$ Eq(1)
The ...
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0answers
38 views
Modeling Question
A pipe carrying 1,2,3 trimethylbenzene (TMB) develops a leaky joint. 2 ml per minute leaks from the pipe and evaporates. The room area surrounding the pipe is fairly open with no directional air flow. ...
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0answers
9 views
Modeling of a Wireless Channel with known BER
I have to model through software a wireless (my choice: 3g,4g, 802.11...) channel with given Bit Error Rate. I'm searching some distributions, I'm reading tons of papers but I can't find how to ...
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1answer
17 views
Drucker-Prager Model Parameters, a Proper Choice
My task is to write a code from scratch for 3D elastoplasticity, namely a DP model (see for example DeSouza Neto, et al., 2008, Chapter 8) having yield surface
$$ f(\mathbf{\sigma},c) = \sqrt{J_2(\...
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2answers
28 views
What is the engineering way to describe a factory / manufacturing plant system in a formel and mathematical way
I am interested in mathematically describing as well as formalising a manufacturing plant so that other people in the engineering field understand how the system works. I am not from the engineering ...
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0answers
15 views
Source for learning Functional derivative , Gateaux derivative
I have started doing research in optimal control theory. My area of research is PDE constrained optimization.
I am facing significant difficulty in deriving the Gateaux Derivative of functionals ...
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0answers
22 views
Developing a model of rate of cooling of steel tube in air
I am trying to develop an equation to determine the cooling rate of a steel tube in air. I'm using Fourier's Law, Stefan-Boltzman Law, Newton's Law as well as the specific heat capacity equation. The ...
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2answers
52 views
Is there any device that can capture a picture into 3D model?
I am currently wondering is there any way or device that can transform a picture into 3D model automatically?
or a machine learning thing to learn from picture (2D) into 3D model?
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1answer
42 views
Torsional rigidity D vs torsional rigidity factor k vs torsion constant J
I have a physics background so apologize my ignorance.
I'm confused by the constants $D$, $\kappa$, and $J$ when it comes to torsion of beams. From what I understand $\kappa$ and $J$ are the same ...
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0answers
37 views
Am I estimating thrust of a ducted fan correctly?
I'm asking if I'm doing this correctly.
I've estimated the thrust of a ducted-fan model aircraft neglecting pressure changes across the duct as follows:
$$F = Q * \rho * (V_e - V_0)$$
$$= Q * rho * (...
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0answers
34 views
“Freeze”/Mold paper in a certain bent position [closed]
I have a piece of paper (lets says its a A4) and I bent it in a certain way (like a skateboard ramp, I'm holding the ends and the middle kind of falls forming this "ramp" model), but now I need a way ...
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0answers
33 views
Method to simulate a dipole antenna in salt water?
I am looking to simulate the radiation pattern of a 2.7Ghz half-wavelength dipole antenna immersed in salt water.
I've been using Altair FEKO software to try and accomplish this. I've tried two ...
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1answer
51 views
How are NPT hole features defined?
I'll be the first to admit that I have always been somewhat confused by best-practice dimensioning standards surrounding pipe threads. While there is a decent amount of literature available online, (...
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2answers
89 views
Viscoelasticity and Hyperelastic model, history and difference
Actually, I see some papers use viscoelasticity or hyperelastic model for the same materials. It seems to me that those models were invented in different eras, and the hyperelastic is a newer model ...
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1answer
28 views
How to get the surface area of trajectory [MSC Adams]?
I'm not sure if the upper question is clear enough to understand but here's what I've got:
I've made a model of excavator in Adams View and got trajectory of it's motion (boom, stick, bucket) using ...
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1answer
34 views
Parametric equations for fan blades
I'm looking for an explicit numerical example of a parametric surface (u, v) |-> (x(u, v), y(u, v), z(u, v)) that models a fan blade like that in the attached picture.
Googling results in NURBS/PDE ...
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2answers
41 views
Example of real-life problem solved with numerical methods? [closed]
I hope this is a suitable question to ask here.
Well, I'm taking Numerical Methods this semester (also called 'Numerical Analysis' in some places).
The term-assignment is to find a real-life problem ...
3
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1answer
58 views
Modelling gas desorption from a still solution (e.g. a beer)
The common way to model or estimate gas (e.g. CO2) desorption rate from a liquid solution is by using an equation similar to this one
$J_{CO_2} = -k_L a(H·C^G_{CO_2} - C^L_{CO_2})$
where $J_{CO_2}$ ...
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4answers
92 views
Git, Mercurial, others — what's the best system for an engineering team new to version control?
I recently started working with a new team doing detailed energy modeling for all flavors of building projects -- commercial, industrial, residential, new construction, renovations, additions. As the ...
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0answers
47 views
How to join two beams rigidly?
Hi I am making a beam model using Abaqus. There are two beams created. I wanted to join two beams rigidly in the connection to transfer moments between beams. However, I do not know what connector or ...
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2answers
71 views
How do you read a blower/compressor curve with multi-curves for inlet guide vanes?
I am trying to apply an existing blower curve in a hydraulic model for a single stage blower with variable inlet diffuser vanes. The variety of curves shown on the plot does not seem to make sense to ...
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1answer
86 views
How to make datum planes on a cone in Creo?
I am trying to make this
I was able to make the base feature but I am facing problems with the secondary features. So could anyone shed some light on how to make the datum planes on cones.
I made ...
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1answer
53 views
How does the superposition principle relate to Bernoulli-Euler and Timoshenko beam theory? [closed]
I have a shaft with a bearing in each end, and a large eccentric mass covering the entire "free length" of the shaft.
The attachment of the eccentric mass is done using heat shrinking.
Without ...
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0answers
52 views
Bad triangular-shell elements in Abaqus?
Abaqus 6.14
I have a 2D shell mesh reconstructed from a *.ply file. When I verify the mesh I get 55% bad elements (CPS3).
So I get a list of all the bad elements & reconstruct the mesh again ...
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1answer
47 views
Predicting frequencies, decays, levels, and phases of modes of a circular membrane (drum head)?
I have been working on some acoustic synthesis software for modelling several acoustic instruments. I am using the principle of modal synthesis, where every mode of vibration is individually ...
0
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1answer
40 views
Modeling the stiffness of a membrane
I'm trying to model, in MATLAB, a membrane in 2D which has an initial triangle-like shape.
This membrane has pressure acting on it from the inside. There are also some pulling forces in random ...
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0answers
17 views
How to export my model as Solid model IGES Type 186 on Rhino?
I'm not able to find that option while exporting. I need to export this to ANSYS where the other available IGES formats come as only surface models.
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0answers
41 views
False turbulence in laminar flow with k-omega SST
I have a pipe with a sudden expansion from 0.25 mm to 1 mm. Fully developed flow is at the inlet and a reynolds number of 500.
I use k-omega SST turbulence model because laminar simulation hasn't ...
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1answer
87 views
What is the advantage of successive linearization?
In this link, two methods have been referred for linearization.
1- offline linearization
2- online linearization
However, I do not understand what is the role of "successive linearization" in the ...
3
votes
2answers
31 views
How to estimate the time cost of interrupting a task and picking it up again later
In terms of personal productivity (single machine scheduling) when a task is interrupted before being done in order to switch to a different task, it incurres a 'tear down' time cost - putting tools, ...
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0answers
60 views
How to run response spectrum for members with compression only spring in MIDAS
When running a structural model supported on footings with compression only springs, I encountered tension reaction forces in the springs. This occurs when running seismic load case using response ...
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1answer
38 views
Thermal Modeling
I have an electronic assembly and part of what it does is to measure and report temperature. The electronics are housed is a plastic enclosure, and there is a small fan blowing out of the enclosure. ...
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1answer
31 views
simplified acceleration and max speed calculations for a game? [closed]
Are there any simplified formulas that could be used to generate plausible airplane, spaceplane/SSTO, and spacecraft performance specs for a game given some basic vehicle and contextual attributes? By ...
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1answer
38 views
Explain each of the values output by HEC-RAS
I am looking at a Flood Risk Assessment that uses HEC-RAS to model the predicted levels of flooding on a piece of land. As shown in the attached image, the report lists a number of variables with ...
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0answers
15 views
How to find the maximum misalignment from vibration?
Consider the system in the (drawn in Paint) image. Assume that there is an input acceleration at the ground defined by a PSD. This acceleration can be in any axis. Points A and B are initially aligned ...
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1answer
104 views
Questions regarding Cornering Stiffness for RC Car
I am a bachelor's level student tasked with modeling the vehicle dynamics of an RC Car that will be made to drive autonomously. I lack prior experience or particularly specific education with vehicle ...
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2answers
97 views
Failure of N.R.T.L method to model Phenol / Methylcyclohexane / Toluene system in AspenPlus. Why?
I have an extractive distillation column set up in AspenPlus. Methylcyclohexane (MCH) is expected to come out from the top (in the distillate stream) and the bottoms stream is mostly Toluene/Phenol, ...
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1answer
160 views
Energy consumption of a boiler
I have a question that maybe will be very easy for you.
I am working on a district heating model using Dymola, and now I have to incorporate a boiler into my model, such as this one.
I was asked to ...
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1answer
86 views
Would a partial space elevator work? [closed]
Background
The normal space elevator (that reaches from the Earth's surface to a counterweight beyond geostationary) needs a material that's strength/weight ratio is better than any material we have ...
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1answer
56 views
How to determine the degrees of freedom for ball and beam system such as shown in pic below
Since, motion of the ball on the beam depends on the beam angle alpha, shouldn't this system have a single degree of freedom?
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11answers
8k views
From an engineering point of view what are the downsides of a too accurate model?
I was wondering, from an engineering point of view, for what reasons can too much accuracy in modeling be detrimental?
From a scientific point of view it seems like it's almost always a benefit, ...
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1answer
55 views
What is an unstructured mathematical model?
I want to model a chemical process. I was searching in the literature to find similar works. In some of papers they say that "we proposed an unstructured model". What does it mean? What is the ...
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3answers
93 views
What program to implement mathematical models? [closed]
I am an engineering student and recently came upon some articles that provide numerical models that relate electromagnetic fields and temperature. I want to test out these numerical models but am ...
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0answers
20 views
Linear Guidance law into X-Y axis
Im currently writing a model for a guidance law named Maintaining Guidance law.
The law looks as following: $$ a_{M} = [K_1,K_2]*[\dot{\lambda_T} ,\dot{\lambda_D}]'$$
Since im using a linear model I ...
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1answer
319 views
polar moment of inertia for compound shape
I have a shape that I'd like to calculate the polar moment of inertia for:
the diameter is 600mm; the hexagon in the middle sides are 70mm each; the holes around the hexagon are 130mm from the center ...
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1answer
311 views
Maximum torsion shear stress in cylinder
I am trying to figure out am I doing this calculation correctly.
To get the maximum shear stress for a solid cylindrical pipe I need two formulas:
Moment of inertia = pi/2*r^4
Not sure what this ...
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2answers
71 views
moment of inertia forces and torque
I did some calculations to find out the moment of inertia and physical qualities of some metal.
I am using typical medium carbon steel.
I'll use a density of 7.8 g/m^3 until I get better numbers.
...
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2answers
252 views
Looking for program and file format for CNC Milling
I am creating subwoofer boxes out of MDF or Baltic Birch. My local makerspace has a CNC machine. I am going to make all of the cuts with it.
What software is generally used or will work to get a ...
2
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0answers
30 views
Holonomic constraint forces using Lagrange multipliers
Consider a multibody robotic system with Lagrangian $$ L =\frac{1}{2} \dot{q}^{T}M\dot{q} - V $$ and equations of motion of the form
$$M(q)\ddot{q}+C(q,\dot{q})\dot{q}+A^{T}(q)\lambda+N(q)=0 $$
where ...
0
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1answer
153 views
How to use failure criteria in isotropic material (NASTRAN)
I'm quite new in NASTRAN enviroment, and I am wondering how to use failure criteria which I can define when creating my isotropic MAT1 material for 1D elements (like CBEAM).
From the Quick Reference ...
