China 
Africa 
Explore chapters and articles related to this topic
Introduction
Published in Ansel C. Ugural, Mechanical Engineering Design, 2022
A static load is applied slowly, gradually increasing from zero to its maximum value and thereafter remaining constant. Thus, a static load can be a stationary (i.e., unchanging in magnitude, point of application, and direction) force, torque, moment, or a combination of these acting on a member. In contrast, dynamic loads may be applied very suddenly, causing vibration of the structure, or they may change in magnitude with time. Note that, unless otherwise stated, we assume in this book that the weight of the body can be neglected and that the load is static. As observed earlier, in SI, force is expressed in newtons (N). But, because the newton is a small quantity, the kilonewton (kN) is often used in practice. The unit of force in the US customary system is pounds (lb) or kilopounds (kips).
Introduction
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
A static load is applied slowly, gradually increasing from zero to its maximum value and thereafter remaining constant. Thus, a static load can be a stationary (i.e., unchanging in magnitude, point of application, and direction) force, torque, moment, or a combination of these acting on a member. In contrast, dynamic loads may be applied very suddenly, causing vibration of the structure, or they may change in magnitude with time. Note that, unless otherwise stated, we assume in this book that the weight of the body can be neglected and that the load is static. As observed earlier, in SI, force is expressed in newtons (N). But, because the newton is a small quantity, the kilonewton (kN) is often used in practice. The unit of force in the US customary system is pounds (lb) or kilopounds (kips).
Statics
Published in Bjørn N. Sandaker, Arne P. Eggen, Mark R. Cruvellier, The Structural Basis of Architecture, 2019
Bjørn N. Sandaker, Arne P. Eggen, Mark R. Cruvellier
Mass is measured in kilograms, kg (slugs).3 If we multiply acceleration by mass we will have a unit for force written as kgm/s2 (slug-ft/s2). This force unit in the Système International (SI) aptly is called Newton, N. Trying to grasp what this unit represents physically, we may think of the weight of one fairly large apple, linking the unit to the legend of Isaac Newton having an apple fall on to his head. Here we acknowledge the most common force of all, the force of gravity, also known as weight, which is the force that pulls all material bodies in the direction of the center of the earth. For this force we can write W = mg where W = the force of gravity acting on a body having a mass of m, with the acceleration in this case being the gravitational constant g = 9.81m/s2 (32.2ft/s2) applying in the context of the gravity of the earth. According to Imperial or American standards, the force unit (slug-ft/s2) is called pound, abbreviated lb.4 One pound is approximately 4.45N. Since 1N is a fairly small force, it is convenient to also operate with 1000N as a unit for force; this unit is called kiloNewton (kN). Parallel to this we find in the Anglo-American tradition the force unit called kip, which is the same as 1000lb.
How do technique and coordination change during learning of a whole-body task: Application to the upstart in gymnastics
Published in Journal of Sports Sciences, 2019
Michael J. Hiley, Nicole Schmid, Maurice R. Yeadon
The upstart is a fundamental skill in gymnastics, requiring co-ordination of the body segments with the swing about the bar, and is used to transfer the gymnast from a swing beneath the bar to a position of support above the bar (Figure 1). The skill is employed by elite and beginner gymnasts in men’s and women’s artistic gymnastics on various pieces of apparatus which incorporate swinging skills. The basic technique of an upstart comprises a swinging phase to a position of body extension (Figure 1(a,b)) followed by a “kip” phase (Figure 1(c,d)) to raise the centre of mass to the bar. To receive no deductions from the judges (Fédération Internationale de Gymnastique, 2017) the gymnast must show good extension at the front of the swing and perform the whole skill fluently with straight arms and legs.
Parameter identification of Bouc–Wen type hysteresis models using homotopy optimization
Published in Mechanics Based Design of Structures and Machines, 2022
R. Manikantan, T. Ghosh Mondal, S. Suriya Prakash, C. P. Vyasarayani
To demonstrate the capability of the homotopy algorithm, experimental data obtained from the quasi-static test (QST) of a single-story steel frame structure (Mohammed 2017) is used for the estimation of the BW model parameters. The estimated parameters are then used to simulate the hysteretic response of the structure numerically. The test specimen consists of four steel columns with a lumped mass of 525.4 kg (0.003 kip-s2/in.) representing a single-story building. The structure is fixed at the bottom, and a hydraulic actuator connected at the top. The details of the test setup are presented in Mohammed (2017). The system is subjected to a quasi-static cyclic loading as shown in Fig. 9(a), and the hysteretic response obtained from the experimental setup is depicted in Fig. 9(b). The experimental test data is collected over a time period of seconds with a sampling time of 0.01 seconds. By substituting the force-displacement data in Eq. (13), the parameter identification process is carried out using the homotopy algorithm. After a few iterations, all the parameters converged to near-global optimum with a minimal error of J = 387. Because of the measurement noise, the error reduces to a minimal value instead of zero otherwise. The convergence of the parameters during the optimization process is shown in Fig. 10. Using the identified parameters, numerical simulation of the hysteretic response is presented in Fig. 11. The close correlation between experimentally measured response and model predictions as observed in Figs. 11(a) and 11(b) demonstrate the robustness of homotopy algorithm in dealing with real experimental data. The identified parameters are summarized in Table 7.
Fatigue life updating of embedded miter gate anchorages of navigation locks using full-scale laboratory testing
Published in Structure and Infrastructure Engineering, 2023
Brian A. Eick, Nathaniel M. Levine, Matthew D. Smith, Billie F. Spencer
To apply a force representative of the overturning reaction of an in-service miter gate, two 979 kN (220 kip) actuators were setup to pull on the specimen in sync. Successful use of two synchronised actuators required the fabrication of a spreader beam and erection of supports in the lab for the actuators. A schematic of the actuator setup is shown in Figure 14, and the full test setup for phase 1 is shown in Figure 9 above. For all phases of the experiment, the load was only applied in tension.