Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: impact mass

Sortuj według:

Ogranicz wyniki do:

Impact resistance of RC beams under different combinations of mass and velocity: mesoscale numerical analysis

Jin Liu, Lan Yuchang, Zhang Renbo, Du Xiuli

Archives of Civil and Mechanical Engineering

2020

Vol. 20, no. 4

308--328

The concrete structures under impact loading duress may be destroyed within an extremely short period of time. The importance and complexity of exploration on the impact resistance of concrete members make this area still open for discussion. In the present study, a 3-D mesoscale numerical model was established to investigate the effect of the combination of impact mass and velocity on the mechanical behavior of reinforced concrete (RC) beams subjected to impact loadings. Heterogeneity of concrete and strain rate effects of concrete and steel bars were taken into account. Furthermore, nonlinear interaction between the concrete and steel bars was considered herein. Results from macroscale and mesoscale simulation were compared with the available physical tests, indicating that the mesoscale numerical model can better represent the influence of heterogeneity of concrete on the mechanical behavior of RC beams. Five different impact energy levels were involved to study the effect of the combination of impact mass and velocity on the impact resistance of RC beams. At last, the residual bearing capacity and natural frequency of impacted RC beams were numerically calculated and their relationship was discussed. It is indicated that the deformation of RC beams is influenced strongly by the impulse, which increases with the increasing impact mass at identical impact energy. Besides, the failure mode of RC beams turns from shear-dominant failure mode to bending shear failure mode with the increase of impact mass, accompanied by the increase of energy dissipation of steel bars and the whole member. Despite this, in the present work, the combination of the impact mass and velocity had little influence on the damage extent (based on the performance) of the RC beams. Moreover, an empirical relationship between the residual bearing capacity and the natural frequency of the impacted RC beams was established as a rough reference for damage evaluation in engineering practice.

Badania modelowe złącza ciernego obciążonego udarem masy

Brodny J.

Górnictwo i Geologia

2012

T. 7, z. 1

15-26

Prowadzenie badań stanowiskowych złączy ciernych obciążonych dynamicznie jest kosztowne i wymaga posiadania odpowiednio wyposażonego, specjalistycznego stanowiska badawczego. Dlatego do analizy pracy złącza ciernego obciążonego udarem swobodnie spadającej masy wykorzystano symulacje numeryczne oparte na metodzie elementów skończonych. Model fizyczny złącza ciernego opracowano, opierając się na układzie stosowanym w czasie badań stanowiskowych. Do rozwiązania modelu matematycznego wykorzystano metodę całkowania jawnego (explicite). W wyniku przeprowadzonych analiz wyznaczono przebiegi czasowe siły przenoszonej przez złącze cierne oraz przemieszczenia zsuwającego się kształtownika. Na podstawie wyznaczonych przebiegów określono zależności pomiędzy maksymalną wartością siły przenoszonej przez złącze cierne a wysokością, z jakiej spada masa udarowa, oraz wartością współczynnika tarcia statycznego między współpracującymi kształtownikami. Wyznaczono także rozkłady naprężeń zredukowanych w elementach złącza ciernego oraz określono stan ich odkształcenia.

Conduction of stand tests of the frictional joints loaded dynamically is expensive and requires possession of properly equipped specialized test stand. Therefore for analysis of operation of the frictional joint loaded with an impact of freely falling mass, numerical simulations based on the finite element method were used. Physical model of the frictional joint was developed on the basis of system applied during the stand tests. To solve mathematical model an explicit integration method was used. In result of analyses carried out, temporal courses of force transmitted through the frictional joint, and displacements of section sliding down were determined. On the basis of determined temporal courses, dependences between maximum value of force transmitted through the frictional joint, and the height from which the impact mass falls down, and the value of static friction coefficient between cooperating sections were determined. Distributions of reduced stresses in elements of frictional joint were also determined and the state of deformation was described.