Temat: deflection curve - Prolib Integro

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Tytuł:: A new method for generating virtual models of nonlinear helical springs based on a rigorous mathematical model
Autorzy:: Michalczyk, Krzysztof
Warzecha, Mariusz
Baran, Robert
Tematy:: helical spring
spring design
spring stiffness
load-deflection curve
spring geometry; Pokaż więcej
Wydawca:: Polskie Towarzystwo Promocji Wiedzy
Powiązania:: https://bibliotekanauki.pl/articles/30148247.pdf Link otwiera się w nowym oknie
Opis:: This paper presents a new method for generating nonlinear helical spring geometries based on a rigorous mathematical formulation. The model was developed for two scenarios for modifying a spring with a stepped helix angle: for a fixed helix angle of the active coils and for a fixed overall height of the spring. It allows the development of compression spring geometries with non-linear load-deflection curves, while maintaining predetermined values of selected geometrical parameters, such as the number of passive and active coils and the total height or helix angle of the linear segment of the active coils. Based on the proposed models, Python scripts were developed that can be implemented in any CAD software offering scripting capabilities or equipped with Application Programming Interfaces. Examples of scripts that use the developed model to generate the geometry of selected springs are presented. FEM analyses of quasi-static compression tests carried out for these spring models showed that springs with a wide range of variation in static load-deflection curves, including progressive springs with a high degree of nonlinearity in characteristics, can be obtained using the proposed tools. The obtained load-deflection curves can be described with a high degree of accuracy by power function. The proposed method can find applications in both machine design and spring manufacturing.
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Load-deflection characteristics of steel, polypropylene and hybrid fiber reinforced concrete beams
Autorzy:: Tamil Selvi, M.
Thandavamoorthy, T. S.
Tematy:: włókno stalowe
włókno polipropylenowe
moduł sprężystości
obciążenie
krzywa ugięcia
sztywność
steel fiber
polypropylene fibre
elasticity modulus
load
deflection curve
stiffness; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/230679.pdf Link otwiera się w nowym oknie
Opis:: Concrete is the most widely used construction material because of its specialty of being cast into any desired shape. The main requirements of earthquake resistant structures are good ductility and energy absorption capacity. Fiber reinforced concrete possesses high flexural and tensile strength, improved ductility, and high energy absorption over the conventional concrete in sustaining dynamic loads. The aim of this paper is to compare the properties of concrete beams in which three types of fibers are added individually. Steel fibers, polypropylene fibers and hybrid fibers were added to concrete in the weight ratio of four percentages in the preparation of four beam specimens. The fourth specimen did not contain fibers and acted as a control specimen. The dimensions of the beam specimens were 150 mm × 150 mm × 700 mm. The reinforced concrete beams of M30 grade concrete were prepared for casting and testing. Various parameters such as load carrying capacity, stiffness degradation, ductility characteristics and energy absorption capacity of FRC beams were compared with that of RC beams. The companion specimens were cast and tested to study strength properties and then the results were compared. All the beams were tested under three point bending under Universal Testing Machine (UTM). The results were evaluated with respect to modulus of elasticity, first crack load, ultimate load, and ultimate deflection. The test result shows that use of hybrid fiber improves the flexural performance of the reinforced concrete beams. The flexural behavior and stiffness of the tested beams were calculated, and compared with respect to their load carrying capacities. Comparison was also made with theoretical calculations in order to determine the load-deflection curves of the tested beams. Results of the experimental programme were compared with theoretical predictions. Based on the results of the experimental programme, it can be concluded that the addition of steel, polypropylene and hybrid fibers by 4% by weight of cement (but 2.14 % by volume of cement) had the best effect on the stiffness and energy absorption capacity of the beams.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Parametryzacja krzywej ugięć nawierzchni podatnych
Parametrisation of deflection curve flexible pavement
Autorzy:: Pożarycki, Andrzej
Górnaś, Przemysław
Bilski, Marcin
Turkot, Adam
Tematy:: krzywa ugięć
parametry krzywej ugięć
nawierzchnie podatne
odcinek doświadczalny
aproksymacja
rozkład t-Studenta
deflection curve
deflection basin parameters
flexible pavements
test section
approximation
t-Student distribution; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Komunikacji Rzeczpospolitej Polskiej
Powiązania:: https://bibliotekanauki.pl/articles/143854.pdf Link otwiera się w nowym oknie
Opis:: W artykule opisano koncepcję wyrażenia dyskretnej postaci krzywej ugięć nawierzchni funkcją ciągłą, której jądro ma postać rozkładu t-Studenta. Przedstawiona postać funkcji (funkcji aproksymacyjnej) zależy od czterech parametrów, które poddano analizie pod kątem możliwości wykorzystania ich do formułowania prostych kryteriów oceny stanu technicznego nawierzchni metodami semi-inwazyjnymi. Przyjmując na podstawie literatury formułę oceny stanu technicznego podłoża nawierzchni przy wykorzystaniu parametru czaszy ugięć znanego jako BCI ustalono, że jeden z parametrów funkcji aproksymacyjnej wskazuje na identyczne zmiany stanu technicznego podłoża nawierzchni odcinka testowego. Tym samym potwierdza się przesłanie, że zarówno na podstawie parametrów sformułowanych w sposób klasyczny, jak i proponowanych przez autorów artykułu, można budować empiryczne kryteria oceny stanu technicznego nawierzchni, wspierając jednocześnie metodykę tworzenia strategii utrzymania w systemach zarządzania nawierzchnią.
The paper describes the concept of expressing the discrete form of the pavement deflection curve with a continuous function, the kernel of which is in the form of a Student’s t-distribution. The presented form of the function (approximation function) depends on four parameters, which were analyzed in terms of the possibility of using them to formulate simple criteria for assessing the technical condition of the pavement using semi-invasive methods (like FWD type methods). Assuming, based on the technical description of the known formula of BCI parameter for assessing the technical condition of the pavement subbase, it was determined that one of the parameters of the approximation function lead to the same conclusions as ones based on BCI values. This confirms the message that both based on parameters formulated in a classical way and those proposed by the authors of this article, one can build empirical criteria for assessing the technical condition of the pavement, while supporting the methodology of creating a maintenance strategies in pavement management systems.
Dostawca treści:: Biblioteka Nauki

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