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Why am I getting a messy signal FFT instead of a smooth one?

Submitted by r_1159 on
research

Hi

I am doing wave simulation on plates with various damages. Guided sinusoidal waves are generated and scattered throughout the plate. To compare the results I am getting FFt of displacement (frequency domain). The one without damage gives me a very smooth FFT while the ones with damage give me a messy FFT ( Please see the attached photo). Is it something to do with filtering or is any thing wrong with my results ?

 

Damages model

http://oi42.tinypic.com/zo6ty9.jpg



Undamaged model

Residual stresses in elastic medium upon uniform cooling

Submitted by dhananj on
elasticity
viscoelasticity
residual stress
Thermal stresses

Hi All,

I am a student working on a project involving the effect of residual stresses in elastic and viscoealstic materials. I have a related question: When an easltic body is heated to a certain temperature (say 400 deg C) and then cooled uniformly to room temperature (20 deg C) with a constant cooling rate "q", does this generate any "un-desirable" (residual) stresses within the elastic body? i.e at a steady state - room temperature, does the final stress state within the body would be non-zero? Else, it would eventually reach a state of zero stresses? How?  

Massvolume vs. Spacetime

Submitted by Zhigang Suo on
education
linear algebra
spacetime

Apples and oranges. Each element in a set is a pile containing some number of apples and some number of oranges.  Adding two piles means putting them together, resulting in a pile in the set. Multiplying a pile and a real number r means finding in the set a pile r times the amount.  We model each pile as a vector, and the set as a two-dimensional vector space over the field of real numbers.

Elsevier is pleased to support the first MOOC(Massive Open Online Course) by Eindhoven Univ. of Technology in the Netherlands

Submitted by Laure Ballu on
education
fluid mechanics
Aerodynamics
wind energy
Computational Fluid Dynamics
WIND
buildings
MOOC
Massive Open Online Course
Eindhoven
Sports
Cycling
Athletics
Bahrain World Trade Center
Wind Tunnel

Title of the course: New insights in Sports and Building Aerodynamics

The course is offered on the Coursera platform and registration is free of charge. To find out more about it and watch the video, go to http://www.journals.elsevier.com/building-and-environment/news/new-insights-in-sports-and-building-aerodynamics/

 

 

Dynamic Brittle Fracture as a Small Horizon Limit of Peridynamics

Submitted by Robert Lipton on
research
dynamic fracture

Overview: The peridynamic formulation is a
spatially nonlocal derivative free model for simulating problems of free crack
propagation.Material points interact through short-range forces and the
formulation allows for discontinuous deformations. Here the short-range forces
are initially elastic and soften beyond a critical relative displacement. We
upscale this peridynamic model to find the macroscopic (a.k.a. small horizon)
limit. It is shown that the limiting macroscopic evolution has bounded energy
given by the bulk and surface energies of brittle fracture mechanics. The
macroscopic evolution corresponds to the simultaneous evolution
of the fracture surface and linear elastic displacement away from the crack

Curvature effect on nitinol aortic stent

Submitted by ankur2626 on
research
ABAQUS
Nitinol
curvature
aotic stent

high i am a student doing a project on curvature effect on thoracic stent. I want to curve the nitinol stent in abaqus. I am using RSURFU and doing static analysis. But am not able to curve it. Also when using implicit dynamic analysis with quasi static apllication my KE is high and comparable to IE. So can any body help me. Crimping and expansion is not a problem.

 

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