{"id":438376,"date":"2025-08-01T13:54:13","date_gmt":"2025-08-01T13:54:13","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/help-with-transient-structural-simulation-to-observe-higher-harmonics-using-fft\/"},"modified":"2025-08-01T13:54:13","modified_gmt":"2025-08-01T13:54:13","slug":"help-with-transient-structural-simulation-to-observe-higher-harmonics-using-fft","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/help-with-transient-structural-simulation-to-observe-higher-harmonics-using-fft\/","title":{"rendered":"Help with Transient Structural simulation to observe higher harmonics using FFT"},"content":{"rendered":"

<p>Hi everyone,<br>I am doing a research for my Master Thesis on excitation properties of Piezoceramic Transducers used in nonlinear acoustics.<br>For that I am performing a simulation in order to choose the best transducer for my experiments with laserovibrometer. Firstly I intended to use Couple Field Electric type of simulation to actualy cause piezo to deform and induce the Shear horizontal wave in thinwalled plate(500mmx500mmx1mm) made of copper\/aluminium. But hence it is really computationally demanding simulation I decided to split the simulations to two. One that is exciting the piezo for collection of the deformation data from edges of the piezo. Second to use this data as a Displacement input on plate to see how the wave propagates and then use output for plotting wave charts etc.<br>The problem is that I now need to choose the correct nonlinear material model for the aluminium plate in order to be able to observe the higher harmonics on the output. But none of what I did gave me satisfactory results. Here are my simulation data:<br>Type of simulation: Transient Structural<br>Material: Alluminium alloy with neohookean\/bilinear non linear models to intrudce nonlinearity ( find the photo of material data in the attachement)<br>Mesh: 1.5mm as it is small as I could get to saving computational time(It is still around 10h)<br>Displacement excitation ( find photo of the wave in the attachements) It is a hamming windowed sine wave of 150kHz with 5 cycles and amplitude of 1e-6 ( as it is the bigger theoretical displacement of piezo transducer)<br>I am collecting the deformation\/velocity data in each of the directions X,Y,Z from points that are 100mm from the excitation point in the 1\/4th of a circle one point on 1 degree from 0 to 90.<br>Time step of the simulation is a time step of the input signal.<br>Simulation time: I found that for the wave to propagate up to point I want to read it i need around 5*the signal length.<br>I need to take the output signal from the simulation and perform a fourier on it in order to observe higher harmonics but nothing significant shows up ( also screenshot attached)<br>Does any of you have an Idea of what to do or did something similar and is able to help urgently?<\/p><p>\"\"<\/p><p><\/p><p><\/p><\/p>\n","protected":false},"template":"","class_list":["post-438376","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27791"],"_bbp_topic_id":["438376"],"_bbp_subscription":["580523","88"],"_bbp_author_ip":["91.235.160.185"],"_bbp_last_reply_id":["439072"],"_bbp_last_active_id":["439072"],"_bbp_last_active_time":["2025-08-12 12:46:49"],"_bbp_reply_count":["1"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["580523","88"],"_btv_view_count":["96"],"_bbp_topic_status":["unanswered"]},"test":"gwojcikstudent-agh-edu-pl"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/438376","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/438376\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=438376"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}