{"id":214935,"date":"2022-05-18T08:10:31","date_gmt":"2022-05-18T08:10:31","guid":{"rendered":"\/forum\/forums\/reply\/214935\/"},"modified":"2022-07-27T13:02:06","modified_gmt":"2022-07-27T13:02:06","slug":"214935","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/214935\/","title":{"rendered":"Reply To: Questions regarding Modal Analysis and Random Vibration Analysis"},"content":{"rendered":"

Further questions (not enough room in one post):<\/i><\/strong><\/p>\n

Question 4: Type of support <\/strong><\/p>\n

PSD G Acceleration \u00d4\u00c7\u00f4 Should I always select All Supports<\/i> here? All Ansys-videos I watched have used All Supports<\/i>, but they are not specific about why. Let\u00d4\u00c7\u00d6s say that I\u00d4\u00c7\u00d6ve used fixed support in my modal analysis, will it make any difference if I use Fixed Support or All Supports?<\/p>\n

Question 5: Random vibration in x,y,z <\/strong><\/p>\n

Can I apply PSD G Acceleration in X, Y and Z during same simulation or do I need to take them separately? I assume separately. What is happening when I use PSD G in x,y,z simultaneously? I notice that the results change a bit.<\/p>\n

\/forum\/discussion\/10768\/combining-multi-axis-psd-vibration-results<\/a><\/p>\n

<\/p>\n

Question 6: What does the PSD Tool tells me, i.e. what does the PSD counts tell me? I’ve problem understanding this, perhaps one can use the curves below to ease explanation. <\/strong><\/p>\n

According to Mechanical User\u2019s Guide: \u201cYou can apply a\u00a0Response PSD Tool\u00a0to any\u00a0Random Vibration<\/a>\u00a0analysis (only) in order to control the frequency sampling of\u00a0Response PSD probes<\/a>.\u201d<\/p>\n

This is result when performing PSD G Acceleration in X\/Y\/Z-direction, see below. I assume that one only examine the Response PSD in the direction of the PSD G Acceleration, one at a time.<\/p>\n

Since this Response PSD is measured on a vertex, is it the same as when we apply accelerometers (x,y,z)?<\/p>\n

X:<\/strong><\/p>\n

<\/p>\n

Y:<\/strong><\/p>\n

<\/p>\n

Z: <\/strong><\/p>\n

Question 7: What is your recommendation, total deformation and equivalent stress in 1-sigma, 2-sigma or 3-sigma? It seems conservative to use 3-sigma (which is easier to motivate).<\/strong><\/p>\n

Meachanical User\u2019s Guide: \u201cMeaningful equivalent stress is computed using a special algorithm by Segalman-Fulcher. Note that the probability distribution for this equivalent stress is neither Gaussian nor is the mean value zero. However, the \u201c3 \u03c3\u201d rule (multiplying the RMS value by 3) yields a conservative estimate on the upper bound of the equivalent stress.\u201d<\/p>\n

Kind regards<\/p>\n

Albin<\/p>\n","protected":false},"template":"","class_list":["post-214935","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/214935","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/reply"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/214935\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=214935"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}