{"id":233781,"date":"2022-08-25T13:29:06","date_gmt":"2022-08-25T13:29:06","guid":{"rendered":"\/forum\/forums\/topic\/tensile-erosion-and-compression-residual-capacity\/"},"modified":"2022-08-25T13:29:06","modified_gmt":"2022-08-25T13:29:06","slug":"tensile-erosion-and-compression-residual-capacity","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/tensile-erosion-and-compression-residual-capacity\/","title":{"rendered":"Tensile Erosion and Compression residual capacity"},"content":{"rendered":"

Hi everyone!<\/span><\/p>\n

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(@Peteroznewman)<\/span><\/p>\n

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I am trying to study the impact absorption capacity of different materials. The aim is to calibrate the ANSYS model and obtain the deceleration curves (G’s or m\/s2) as a function of material, thickness, contact area, impact velocity and mass of the body to be protected.<\/span><\/p>\n

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All materials are similar but since we have data to validate the results, the material chosen for this POST is EPS (20 kg\/m3). For this, I have Isotropic Elasticity Material properties (Young Modulus and Poisson ratio) and the stress vs. strain curve (compression). This curve has been included in the plasticity model “Multilinear Isotropic Hardening”. Furthermore, Maximum Tensile Stress and Maximum Shear Stress values have been obtained from the available literature.<\/span><\/p>\n

It should be noted that the stress that the material is able to withstand is much higher in compression (see graph below) than tensile\/shear (Tensile Stress = 0.18 MPa and Maximum Shear Stress = 0.33Mpa).<\/span><\/p>\n

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This curve is characterised by three well-defined zones (I) Linear elasticity; (II) Collapse plateau; (III) Densification.<\/span><\/p>\n

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To validate the model, the curves in DIN55471-2 can be used.<\/span><\/p>\n

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\"\"<\/strong><\/p>\n

These experimental curves, for a given factor (drop height \/ cushion thickness), show the maximum deceleration value that would be obtained as a function of Static Surface Load (KN \/ cm2). In our case, we take: drop height=100 cm; cushion thickness=2,5 cm; m=4,7 kg or 46,11 N.<\/span><\/p>\n

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According to stress vs strain curve the previous experimental curve shapes can be explained. There is a minimum of G’s, this minimum occurs if the impact conditions take full advantage of the plastic deformation zone. For lower Static Surface Load, there is also plastic behaviour, but less predominant as there is an important elastic component. Beyond the minimum, for higher Static Surface Load, the material deforms and completes the plastic phase and enters the densification zone, here the stress increases exponentially increasing the G’s value.<\/span><\/p>\n

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If the curve points are simulated using Transient Structural or even, Explicit without a failure criterion, the shape of the curve is equivalent to the experimental curves. However, it is shifted upwards with significantly higher G values (deceleration peak) in all cases. This is because the material has an energy dissipation mechanism through the failure of the material itself, most likely by Tensile and\/or Shear stress. <\/span><\/p>\n

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This is not possible to simulate through Transient Structural so it is done with Explicit, introducing the Failure Criteria through Maximum Tensile Stress and Maximum Shear. <\/span><\/p>\n

The problem is, when the material reaches the values defined for that criterion, the elements are removed from the model. This produces values of G’s similar to those expected in the area before the minimum. However, at values to the right of the minimum, in the zone of densification, the value of G’s shoots up. The reason for this is that the material has failed by tensile\/shear and the erosion method removes the elements, however these elements should separate from each other and remain in place to continue working in compression in their plastic\/densification zone.<\/u><\/span><\/p>\n

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Is there any solution for this?<\/span><\/p>\n

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I am getting desperate with this model and would really appreciate any help as I am not an ANSYS expert although I hope to become!<\/span><\/p>\n

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Many thanks in advance.<\/span><\/p>\n

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Attached is the “xxxxx.wbpz” file, version 2022 R2 (Student).<\/span><\/p>\n

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https:\/\/we.tl\/t-xT5wQinxun<\/span><\/p>\n","protected":false},"template":"","class_list":["post-233781","topic","type-topic","status-closed","hentry","topic-tag-ansys-explicit","topic-tag-compression","topic-tag-erosion-1","topic-tag-material","topic-tag-programming","topic-tag-residual-stress"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["330","240"],"_bbp_author_ip":["23.218.93.53"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1025"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["233781"],"_bbp_forum_id":["27791"],"_bbp_engagement":["240","330"],"_bbp_voice_count":["2"],"_bbp_reply_count":["15"],"_bbp_last_reply_id":["235862"],"_bbp_last_active_id":["235862"],"_bbp_last_active_time":["2022-09-21 07:40:34"]},"test":"glasgowceno"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/233781","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\/233781\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=233781"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}