{"id":387622,"date":"2024-10-01T10:01:59","date_gmt":"2024-10-01T10:01:59","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/shock-response-spectrum-generalized\/"},"modified":"2024-10-01T10:01:59","modified_gmt":"2024-10-01T10:01:59","slug":"shock-response-spectrum-generalized","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/shock-response-spectrum-generalized\/","title":{"rendered":"Shock response spectrum generalized"},"content":{"rendered":"

<p>Hello all,<\/p><p>I recently get interrested in SRS (Shock response spectrum). The theory I understood here is to idealize the system as a 1D mass\/spring\/damped system.<\/p><p>I tried to recreate a simple system with a bushing and a point mass ( I fixed the stiffness of the bushing, I am changing the mass in order to change de natural frequency, Damping numerical=0.005)<\/p><p><\/p><p>Shock impulse is an Half sine curve (Amplitude 3g, duration 30ms)<\/p><p>Boundary condition, the system is in 1D( All displacement blocked but the vertical direction)<\/p><p>Transient simulation data: Duration 0.5s, time step 0.001s, numerical damping (default=0.005)<\/p><p>Here are the results given :<\/p><p><\/p><p>I found in the litterature the following curve that I should have:<\/p><p><\/p><p>My problem is that I don’t have at all the same result, the higher is the natural frequency the lower is the response going to an asymptote close to 0 instead of 1.Do you know what I am missing here?<\/p><p>My guess is that it is link to the numerical damping effect:<\/p><p><\/p><p> <\/p><p>I think I should open a new dicussion about this following topic but I think it is somehow linked.We usualy perform a half sine pulse to a complexe system. In theory the severity of a shock is the velocity change (Energy in the system= 1\/2mv^2).Meaning that a 3g 30ms should be equivalent to a 1.5g 60ms shock, but if I compare the maximum stress of the 2 simulations I dont have at all the same result . Any idea why? ( for me it is driven directly from the amplitude of the shock acceleration, in other hand I understand that the severity of a shock is driven from the velocity)<\/p><p>Thanks for your help :)<\/p><p> <\/p><\/p>\n","protected":false},"template":"","class_list":["post-387622","topic","type-topic","status-publish","hentry","topic-tag-shock","topic-tag-shock-analsysis-1","topic-tag-srs-1"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["102847","20905"],"_bbp_author_ip":["147.161.246.110"],"_btv_view_count":["306"],"_bbp_topic_status":["unanswered"],"_edit_lock":["1727777907:431556"],"_bbp_notification_enabled":["102847"],"_bbp_topic_id":["387622"],"_bbp_forum_id":["27791"],"_bbp_engagement":["20905","102847"],"_bbp_voice_count":["2"],"_bbp_reply_count":["4"],"_bbp_last_reply_id":["388212"],"_bbp_last_active_id":["388212"],"_bbp_last_active_time":["2024-10-04 16:17:08"]},"test":"jerome-chassinhitachienergy-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/387622","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\/387622\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=387622"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}