عنوان مقاله :
آناليز عددي رفتار ديناميكي پادشهودي تيرهاي كشساني - خمير پين دار تحت بار ضربه‌يي با ملاحظه ي اثرات سخت‌شوندگي خطي
عنوان به زبان ديگر :
NUMERICAL ANALYSIS OF THE COUNTER-INTUITIVE DYNAMIC BEHAVIOR OF THE ELASTIC-PLASTIC PIN-ENDED BEAMS UNDER IMPULSIVE LOADING WITH REGARDING THE LINEAR
پديد آورندگان :
شمس عليزاده، مهدي دانشگاه شهيد چمران اهواز - دانشكده مهندسي مكانيك , حيدري شيرازي، كوروش دانشگاه شهيد چمران اهواز - دانشكده مهندسي مكانيك , مرادي، شاپور دانشگاه شهيد چمران اهواز - دانشكده مهندسي مكانيك , محمدصديقي، حميد دانشگاه شهيد چمران اهواز - دانشكده مهندسي مكانيك
كليدواژه :
رفتار پادشهودي , پاسخ غيرعادي , بارگذاري ضربه‌يي , آناليز ديناميكي كشساني ـ خميري
چكيده فارسي :
در اين تحقيق با توسعه‌ي مدل عددي گلركين و با ارائه‌ي الگوريتمي جديد براي اولين بار اثرات سخت‌شوندگي در رفتار ديناميكي پادشهودي تيرهاي كشساني ـ خميري پين‌دار تحت بار ضربه‌يي، مطالعه شده است. براي انجام اين مطالعه، علاوه بر استفاده از روش گلركين، تحليل‌هاي مشابهي نيز به وسيله‌ي كد اجزاي محدود ANSYS/LS-DYNA صورت گرفته و نتايج اين دو روش با يكديگر مقايسه شده است. جزييات منحني‌هاي جابه‌جايي بر حسب زمان نقطه‌ي مياني تير مورد مطالعه قرار گرفته و ناحيه‌ي رخداد رفتار پادشهودي تعيين شده است. محاسبات صورت گرفته با هر دو روش عددي نشان مي‌دهد كه پاسخ پادشهودي، پديده‌يي بسيار حساس به بارگذاري است، به‌گونه‌يي كه تغييري بسيار اندك در ميزان بار ضربه‌يي سبب ظهور آن در دو ناحيه‌ي پيوسته و مجزا مي‌شود. همچنين بررسي نمودارهاي انرژي تير نيز آشكار مي‌سازد كه اين رفتار غيرعادي در نسبت‌هاي مناسب انرژي داخلي به انرژي جنبشي رخ مي‌دهد.
چكيده لاتين :
The Counter-intuitive behavior which means that the permanent deflection of the elastic-plastic beam come to rest in opposite direction of the impulsive loading, normally appears and disappears abruptly, in certain small ranges of the loading and structural parameters. One of the most important issues in the study of this phenomenon is the determination of the influence of the different parameters on this behavior. This present paper studied the effects of hardening in the counter-intuitive dynamic behavior of the elastic-plastic pin-ended beams under impulsive loading, by developing the proposed Galerkin's numerical model and by presenting a novel algorithm. Galerkin's method as well as Finite element code ANSYS/LS-DYNA were applied to study this phenomenon and the results of these two methods have been compared. In order to regard the hardening effects in Galerkin's method, a new algorithm was proposed. To test the validity of our proposed algorithm, the response of the elastic-perfectly
plastic beam was firstly studied, and the hardening effects on the counter-intuitive response was investigated afterwards. The displacement-time history curves of mid-span of the beam were studied in detail and the region of the occurrence of the counter-intuitive behavior was determined. Furthermore, using the finite element code, energy diagrams of the beam were also investigated. It was been found out that the counter-intuitive response is a phenomenon which is very sensitive to loading so that it may appear with a little change in the amount of loading. The results also showed that when considering the hardening effects, both methods predicted two continuous and distinct regions of loading for the occurrence of this phenomenon where the first had a narrower band and occurred in the tight region of the impulsive loading while the next one had a wider band and occurred in the vast region of the impulsive loading. In addition, our investigations on the energy diagrams showed that, this anomalous behavior would occur in the proper proportions of kinetic to internal energy.
عنوان نشريه :
مهندسي مكانيك شريف
عنوان نشريه :
مهندسي مكانيك شريف
