Questions tagged [modeling]
Use this tag for questions about numerical or analytical modeling and simulation of engineered systems.
0
votes
0answers
7 views
How to Calculate the Speed Ratio between two rollers (overdrive of take-up roller) to provide a required Tension web tension
I have a web feed system with a re-winder and I need to apply a tension to the web. I have a driven roller and a take-up roller. I need to calculate how much overdrive to supply to the takeup roller ...
0
votes
0answers
16 views
Calculate additive RPM required in Feed Forward Web Tension Control
In a web tension control system, where feed forward is to be used; a tension set point is desired lets say 20lbs. A load cell system provides feed back A roller on top of two load cells). There will ...
1
vote
0answers
23 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 ...
0
votes
0answers
12 views
Determine the flow through a drain hole in pipe
I have a 1" curved pipe (included angle ~ 100 deg), with exit pointing upwards. I have a drilled hole at the lowest point (10mm). What will be best way to estimate the actual flow through it?
2
votes
1answer
49 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, (...
2
votes
2answers
65 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 ...
0
votes
1answer
25 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 ...
0
votes
0answers
32 views
Iteratively determining conical shock angle from freestream conditions and Taylor-Maccoll Equations
I am currently trying to do a 1D flow analysis of supersonic flow past a semi-infinite cone. My current logic structure is as follows.
1) From given cone angle, $c$, mach number, $M$, and specific ...
0
votes
1answer
29 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 ...
1
vote
2answers
37 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
votes
1answer
55 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 $J_{CO_2}$ ...
1
vote
3answers
74 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 ...
2
votes
0answers
37 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 ...
1
vote
2answers
38 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 ...
0
votes
0answers
15 views
Should I use a regular curve fitting tool or system identification to calibrate/model a gyroscope to a reference?
I want to create a model that describes how well a gyroscope can approximate the angular velocity that I apply to it. Since it's never really possible to obtain the exact angular velocity, it is based ...
0
votes
1answer
50 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 ...
0
votes
1answer
49 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 ...
0
votes
0answers
33 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 ...
1
vote
1answer
39 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
votes
1answer
37 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 ...
0
votes
0answers
15 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.
0
votes
0answers
29 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 ...
0
votes
1answer
58 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
28 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, ...
0
votes
0answers
38 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 ...
0
votes
1answer
31 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. ...
1
vote
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 ...
1
vote
1answer
32 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 ...
1
vote
0answers
12 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 ...
0
votes
0answers
24 views
autocorrelation function of mechanical displacement
I was wondering if there any work in the literature that has been done on the form of the autocorrelation function of mechanical displacement of an object.
4
votes
0answers
71 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 ...
1
vote
2answers
78 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, ...
1
vote
1answer
103 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 ...
5
votes
1answer
81 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 ...
0
votes
1answer
44 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?
23
votes
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, ...
0
votes
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 ...
0
votes
3answers
85 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 ...
1
vote
0answers
19 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 ...
1
vote
1answer
258 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 ...
1
vote
1answer
145 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 ...
0
votes
2answers
69 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.
...
0
votes
2answers
107 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
votes
0answers
26 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
votes
1answer
106 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 ...
3
votes
2answers
152 views
Specification of linear speed dampers
I'm looking at linear compression dampers and finding them most commonly specified only with a "Max Force" – e.g., 270 lbs.
However, since the damping mechanism is provided by hydraulic or pneumatic ...
3
votes
1answer
108 views
Is it possible to apply different boundary conditions on the same model for different load cases?
Instead of creating multiple bridge models with different boundary conditions for differential settlement, and combining the forces output manually in Excel, is it possible to specify different ...
3
votes
1answer
102 views
Should sum of all joint reactions be zero when nodal displacement is applied?
I created a structural model of a laced strut using plate elements. To study second order effects of bow imperfection, I applied a joint displacement of 20 mm in a SAP 2000 v18 model. When the ...
1
vote
0answers
42 views
Best software for 3D modeling and simulation semiconductors? [closed]
Need to design 3D model of photodiode and calculate it (interaction light with semiconductor). What software product would be better for this objective and why?
Important criteria:
Big library ...
1
vote
1answer
227 views
How to model a planetary gear system with transformation matrices?
I need to model the planetary gear-train with transformation matrices of 1 sun and 2 planets system, with no ring and an "arm" or carrier holding the gears ,like in the second picture. I already have ...
