{"id":16568,"date":"2017-03-24T14:52:22","date_gmt":"2017-03-24T13:52:22","guid":{"rendered":"\/en\/interdepartmental-laboratory-of-numerical-modeling\/badania\/metoda-elementow-dyskretnych\/"},"modified":"2017-04-15T21:11:19","modified_gmt":"2017-04-15T19:11:19","slug":"discrete-element-method","status":"publish","type":"page","link":"https:\/\/www.ipan.lublin.pl\/en\/interdepartmental-laboratory-of-numerical-modeling\/research\/discrete-element-method\/","title":{"rendered":"Discrete Element Method"},"content":{"rendered":"

[vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern”][vc_column][vc_column_text]Discrete Element Method (DEM) is one of the numerical approaches able to evaluate trajectories of movement and mutual interactions between particles inside beds of granular materials (e.g. cereal grains, sand, powders etc.). DEM, because of its potential, earned a common acceptance as a useful tool for description of many engineering problems concerning with powdery materials, for example calculation of stress distribution inside the silo, mixing and grinding. The simplest scheme of DEM is presented at the scheme below:[\/vc_column_text][vc_column_text css=”.vc_custom_1492283409658{padding-top: 30px !important;padding-bottom: 30px !important;}”]\"\"[\/vc_column_text][vc_column_text]DEM simulations of flow disturbance around the obstruction<\/span>.[\/vc_column_text][vc_column_text css=”.vc_custom_1490367916126{padding-top: 30px !important;padding-bottom: 30px !important;}”]\"\"[\/vc_column_text][vc_column_text]Fig. 1. Frames from the numerical simulations of discharge of the granular material from\u00a0 cylindrical container without (left) and with insert attached to the silo wall (right). Axial cross-section of a bin with diameter of 0.12 m and height of 0.33 m filled with 75000 spherical particles.
\nIn storage bins there is often a necessity to place an additional construction elements inside the material bed (sensors, feeder covers, stress relieving pipes etc.). The disturbance of stress distribution caused by existence of such elements may lead, in extreme cases, to damaging the whole construction of the silo. Fig. 1 depicts the way in which the flow pattern is affected by the placement of an additional element inside the model silo.[\/vc_column_text][vc_column_text css=”.vc_custom_1490367945983{padding-top: 30px !important;}”]W zbiornikach przechowalniczych cz\u0119sto istnieje konieczno\u015b\u0107 umieszczania dodatkowych element\u00f3w wewn\u0105trz z\u0142o\u017ca (czujniki, os\u0142ony podajnik\u00f3w, rury odci\u0105\u017caj\u0105ce itp.). Zaburzenia rozk\u0142adu napr\u0119\u017ce\u0144 powodowane przez takie elementy mog\u0105 prowadzi\u0107 w skrajnych przypadkach do uszkodzenia ca\u0142ej konstrukcji zbiornika. Rys. 1 przedstawia spos\u00f3b, w jaki zmienia si\u0119 charakter wyp\u0142ywu materia\u0142u sypkiego w modelowym silosie po zamontowaniu p\u00f3\u0142ki przy \u015bcianie.[\/vc_column_text][vc_column_text css=”.vc_custom_1490368226298{padding-top: 30px !important;padding-bottom: 30px !important;}”]\"\"<\/a>[\/vc_column_text][vc_column_text]Koby\u0142ka R<\/a>., Molenda M<\/a>.:\u00a0 DEM simulations of loads on obstruction attached to the wall of a model grain silo and of flow disturbance around the obstruction<\/a> (2014 r.) Powder Technology 2014, Vol. 256, 210-216<\/em><\/strong><\/p>\n

The effect of the particle size distribution on the micro- and macromechanical properties of granular materials.<\/strong><\/p>\n

 <\/p>\n

Most particle packings involved in industrial and natural processes is comprise of a broad range of particle sizes. The degree of particle size heterogeneity determines the geometrical and micromechanical properties of packings during mixing and discharge processes, as well as their mechanical response to external loads due to tableting, granulation et al.. The 3-D simulations were conducted for polydisperse packings composed of spheres with various degrees of particle size polydispersity and with particle size distributions approximated by normal, arbitrary and uniform distribution functions, using the discrete element method (Fig. 1). The analysis of the geometrical and mechanical properties of packings subjected to different compressive loads showed slight effect of the shape of particle size distribution (PSD<\/em>) on the porosity of sample and no effect of PSD<\/em> on the micro- and macromechanical properties of granular materials. The porosity, stiffness of granular packings and pressure ratio in samples were found to increase with increasing standard deviation of particle mean diameter. The increase in the degree of polydispersity of particulate assemblages resulted in decrease in the average coordination number (Fig. 2).[\/vc_column_text][vc_column_text css=”.vc_custom_1490368292785{padding-top: 30px !important;}”]Wi\u0119kszo\u015b\u0107 \u00a0materia\u0142\u00f3w sypkich stanowi o\u015brodki niejednorodne pod wzgl\u0119dem wielko\u015bci cz\u0105stek, a stopie\u0144 ich polidyspersyjno\u015bci determinuje zachowanie materia\u0142\u00f3w w procesach mieszania i opr\u00f3\u017cniania zbiornik\u00f3w przemys\u0142owych oraz reakcj\u0119 materia\u0142\u00f3w poddanych obci\u0105\u017ceniom podczas proces\u00f3w tabletkowania, granulowania i innych.<\/p>\n

Zastosowanie Metody Element\u00f3w Dyskretnych umo\u017cliwi\u0142o przeprowadzenie bada\u0144 nad materia\u0142ami o r\u00f3\u017cnym stopniu niejednorodno\u015bci wielko\u015bci cz\u0105stek, charakteryzuj\u0105cymi si\u0119 r\u00f3\u017cnymi rozk\u0142adami wymiar\u00f3w granul (normalnym, przypadkowym i jednorodnym). Analiza geometrycznych i mechanicznych w\u0142a\u015bciwo\u015bci modelowanych o\u015brodk\u00f3w, poddanych testowi jednoosiowego \u015bciskania (Rys. 1), wykaza\u0142a niewielki wp\u0142yw rodzaju rozk\u0142adu wielko\u015bci cz\u0105stek na porowato\u015b\u0107 o\u015brodk\u00f3w rozdrobnionych oraz jego brak na mikro- i makromechaniczne w\u0142a\u015bciwo\u015bci pr\u00f3bek. Wraz ze wzrostem standardowego odchylenia \u015brednicy sfer obserwowano wzrost porowato\u015bci z\u0142\u00f3\u017c, ich sztywno\u015bci oraz ilorazu naporu. Wzrost stopnia polidyspersyjno\u015bci wielko\u015bci cz\u0105stek prowadzi\u0142 do spadku liczby koordynacyjnej w modelowanych pr\u00f3bkach (Rys. 2).[\/vc_column_text][vc_column_text css=”.vc_custom_1490368422081{padding-top: 30px !important;padding-bottom: 30px !important;}”]\"\"[\/vc_column_text][vc_column_text]Fig. 1. Initial configuration of polydisperse sample with standard deviation of particle mean diameter of 40%.[\/vc_column_text][vc_column_text css=”.vc_custom_1490368510088{padding-top: 30px !important;padding-bottom: 30px !important;}”]\"\"[\/vc_column_text][vc_column_text]Fig. 2. Average coordination numbers for samples with normal particle size distribution and various standard deviations of particle mean diameters.[\/vc_column_text][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

[vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern”][vc_column][vc_column_text]Discrete Element Method (DEM) is one of the numerical approaches able to evaluate…<\/p>\n","protected":false},"author":1,"featured_media":6082,"parent":16567,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"iapan_zaklad_mpmk.php","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-16568","page","type-page","status-publish","has-post-thumbnail","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/pages\/16568","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/comments?post=16568"}],"version-history":[{"count":0,"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/pages\/16568\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/pages\/16567"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/media\/6082"}],"wp:attachment":[{"href":"https:\/\/www.ipan.lublin.pl\/en\/wp-json\/wp\/v2\/media?parent=16568"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}