Cantilever Beam Design for Projectile Internal Moving Mass Systems

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Jonathan Rogers ◽  
Mark Costello
Keyword(s):  
Cantilever Beam ◽  
Damping Ratio ◽  
Effective Control ◽  
Moving Mass ◽  
Control Mechanisms ◽  
Control Force ◽  
Internal Mass ◽  
Mass System ◽  
Electromagnetic Actuators ◽  
Beam Design

Internal masses that undergo controlled translation within a projectile have been shown to be effective control mechanisms for smart weapons. However, internal mass oscillation must occur at the projectile roll frequency to generate sufficient control force. This can lead to high power requirements and place a heavy burden on designers attempting to allocate volume within the projectile for internal mass actuators and power supplies. The work reported here outlines a conceptual design for an internal translating mass system using a cantilever beam and electromagnetic actuators. The cantilever beam acts as the moving mass, vibrating at the projectile roll frequency to generate control force. First, a dynamic model is developed to describe the system. Then the natural frequency, damping ratio, and length of the beam are varied to study their affects on force required and total battery size. Trade studies also examine the effect on force required and total battery size of a roll-rate feedback system that actively changes beam elastic properties. Results show that, with proper sizing and specifications, the cantilever beam control mechanism requires relatively small batteries and low actuator control forces with minimum actuator complexity and space requirements.

Static Nano-Control of Cantilever Beams Using the Inverse Flexoelectric Effect

2011 ◽  
Author(s):  
S. D. Hu ◽  
H. Li ◽  
H. S. Tzou
Keyword(s):  
Electric Field ◽  
Cantilever Beam ◽  
Mechanical Strain ◽  
Effective Control ◽  
Bottom Surface ◽  
Control Force ◽  
Dirac Delta ◽  
Flexoelectric Effect ◽  
Afm Probe ◽  
Converse Piezoelectric Effect

Flexoelectricity, an electromechanical coupling effect, exhibits two opposite electromechanical properties. One is the direct flexoelectric effect that mechanical strain gradient induces an electric polarization (or electric field); the other is the inverse flexoelectric effect that polarization (or electric field) gradient induces internal stress (or strain). The later can serve as an actuation mechanism to control the static deformation of flexible structures. This study focuses on an application of the inverse flexoelectric effect to the static displacement control of a cantilever beam. The flexoelectric layer is covered with an electrode layer on the bottom surface and an AFM probe tip on the top surface in order to generate an inhomogeneous electric field when powered. The control force induced by the inverse flexoelectric effect is evaluated and its spatial distribution resembles a Dirac delta function. Therefore, a “buckling” characteristic happens at the contact point of the beam under the inverse flexoelectric control. The deflection results of the cantilever beam with respect to the AFM probe tip radius indicate that a smaller AFM probe tip achieves a more effective control effect. To evaluate the control effectiveness, the flexoelectric deflections are also compared with those resulting from the converse piezoelectric effect. It is evident that the inverse flexoelectric effect provides much better localized static deflection control of.flexible beams.

Dynamic Vibration Absorber for a Ropeway Carrier

1997 ◽  
Author(s):  
Hiroshi Matsuhisa ◽  
Osamu Nishihara
Keyword(s):  
Natural Frequency ◽  
Damping Ratio ◽  
Vibration Absorber ◽  
Moving Mass ◽  
Dynamic Vibration Absorber ◽  
Damping Effect ◽  
The World ◽  
Dynamic Absorber ◽  
First Time ◽  
Suspended Bridge

Abstract Ropeways such as gondola lifts have attracted increasing interest as a means of transportation in cities. However, swing of ropeway carriers is easily caused by wind, and usually a ropeway cannot operate if the wind velocity exceeds about 15m/s. The study of how to reduce the wind-induced swing of ropeway carriers has attracted many researchers. It had been said that it was impossible to reduce the vibration of pendulum type structures such as ropeway carriers by a dynamic absorber. But in 1993, Matsuhisa showed that the swing of carrier can be reduced by a dynamic absorber if it is located far above or below from the center of oscillation. Based on this finding, a dynamic absorber composed of a moving mass on an arc-shaped track was designed for practical use, and it was installed in chairlift-type carriers and gondola type carriers in snow skiing sites in Japan in 1995 for the first time in the world. It has been shown that a dynamic absorber with the weight of one tenth of the carrier can reduce the swing to half. The liquid dynamic absorber was also investigated. It has the same damping effect as the conventional solid absorber. It is easy to adjust the natural frequency and the damping ratio, and the structure is simple. Therefore, it will be applied for not only ropeway carriers but also ships and rope suspended bridge and others.

Upper limb involuntary tremor reduction using cantilever beam TMDs

2022 ◽  
pp. 107754632110518
Author(s):  
Sarah Gebai ◽  
Gwendal Cumunel ◽  
Mohammad Hammoud ◽  
Gilles Foret ◽  
Emmanuel Roze ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Objective Function ◽  
Cantilever Beam ◽  
Upper Limb ◽  
Wrist Joint ◽  
Angular Displacement ◽  
Damping Ratio ◽  
Vertical Plane ◽  
Cross Sectional ◽  
Flexion Extension

Tuned mass dampers (TMDs) are proposed as a solution to reduce the involuntary tremor at the upper limb of a patient with postural tremor. The upper limb is modeled as a three-degrees-of-freedom rotating system in the vertical plane, with a flexion-extension motion at the joints. The measured extensor carpi radialis signal of a patient is used to excite the dynamic model. We propose a numerical methodology to optimize the parameters of the TMDs in the frequency domain combined with the response in the time domain. The objective function for the optimization of the dynamic problem is the maximum angular displacement of the wrist joint. The optimal stiffness and damping of the TMDs are obtained by satisfying the minimization of the selected objective function. The considered passive absorber is a cantilever beam–like TMD, whose length, beam cross-sectional diameter, and mass position reflect its stiffness for a chosen additional mass. A parametric study of the TMD is conducted to evaluate the effect of the TMD position along the hand segment, the number of TMDs, and the total mass of TMDs. The sensitivity of the TMD to a decrease of its modal damping ratio is studied to meet the range of stainless steel. TMDs are manufactured using stainless steel beams of the same length (9.1 cm) and cross-sectional diameter (0.79 mm), for which the mass (14.13 g) position is adjusted to match the optimal frequency. Three TMDs holding a mass of 14.13 g each cause 89% reduction in the wrist joint angular displacement.

scholarly journals Corporate governance vs. crisis of company

2012 ◽  
Vol 49 (No. 6) ◽  
pp. 275-277
Author(s):  
P. Moulis
Keyword(s):  
Control Mechanism ◽  
Supervisory Board ◽  
Effective Control ◽  
General Assembly ◽  
Joint Stock Company ◽  
Control Mechanisms ◽  
Natural Control ◽  
Stock Company ◽  
Legal Rules ◽  
The Common

There is a lot of available investigations in the area of company crisis reasons problems nowadays. These inquiries were summarised into the indicators of company crisis reasons. The development and level of these indicators is not possible to consider to be company crisis reasons but above all to be its manifestation. The veritable reason of crisis is the absence of effective control mechanisms in the company, especially of the “natural” control mechanisms. The natural control mechanism means such as rises from the substance of joint stock companies (respectively legal rules of joint stock company). There is a presumption of control activities interaction among the General Assembly, Supervisory Board and Board. Control mechanisms work on the common economic principles’ base in this sense and it means that the owner is considered to be the primary managing element and the management acts as the derivative managing element. The assumption of effective economic principles functioning is the existence of standard variable of these relations i. e. the existence of relevant interests.

scholarly journals Displacement-Dependent Damping Inerter System for Seismic Response Control

2019 ◽  
Vol 10 (1) ◽  
pp. 257 ◽  
Author(s):  
Zhipeng Zhao ◽  
Ruifu Zhang ◽  
Yiyao Jiang ◽  
Dario De Domenico ◽  
Chao Pan
Keyword(s):  
Energy Dissipation ◽  
Seismic Response ◽  
Early Stage ◽  
Damping Ratio ◽  
Poor Performance ◽  
Linearization Method ◽  
Structural Deformation ◽  
Stochastic Dynamic ◽  
Control Force ◽  
The Time Domain

Various inerter systems utilizing velocity-dependent damping for vibration control have been developed. However, a velocity-dependent damping element may exhibit relatively poor performance compared to a displacement-dependent damping element (DDE) of equivalent damping ratio, when the structural deformation is small in the early stage of the seismic response. To address this issue, the advantage of DDE in generating a larger control force in the early stage of excitation is promoted here and enhanced by a supplemental inerter-spring-system, thus realizing a proposed novel displacement-dependent damping inerter system (DDIS). First, the influence of various DDIS-parameters is carried out by resorting to the stochastic linearization method to handle non-linear terms. Then, seismic responses of the DDIS-controlled system are evaluated in the time domain taking the non-linearity into account, thus validating the accuracy of the stochastic dynamic analysis. Several design cases are considered, all of which demonstrated damping enhancement and timely control achieved by the DDIS. The results show that the energy dissipation as well as reduction of structural displacement and acceleration accomplished by the proposed system are significant. DDIS suppresses structural responses in a timely manner, as soon as the peak excitation occurs. In addition, it is demonstrated that interactions among the inerter, spring, and DDE, which constitute the damping-enhancement mechanism, lead to a higher energy-dissipation efficiency compared to the DDE alone.

An Approximate Normal Mode Method for Damped Lumped Parameter Systems

1967 ◽  
Vol 89 (4) ◽  
pp. 597-604 ◽  
Author(s):  
A. Seireg ◽  
L. Howard
Keyword(s):  
White Noise ◽  
Normal Mode ◽  
Damping Ratio ◽  
Conservative System ◽  
Random Excitation ◽  
Mass System ◽  
Response Data ◽  
Lumped Parameter ◽  
Mode Method ◽  
Normal Mode Method

An approximate normal mode method is introduced which permits any linear non-conservative system to be solved by super position of uncoupled coordinates. Accuracy of the method was found to be good when checked by digital computer for dynamic damper systems subjected to sinusoidal and white noise random excitation. A technique is presented which permits a mathematical model for a damped multimass system to be constructed entirely from experimentally obtained sinusoidal frequency response data. An expression is derived for optimum damping ratio and natural frequency ratio that will minimize the response of a two-mass system to white noise random excitation.

Robust multi-objective optimization design of active tuned mass damper system to mitigate the vibrations of a high-rise building

2014 ◽  
Vol 229 (1) ◽  
pp. 26-43 ◽  
Author(s):  
S Pourzeynali ◽  
S Salimi
Keyword(s):  
Damping Ratio ◽  
Tuned Mass Damper ◽  
Robust Design Optimization ◽  
Design Parameters ◽  
Control Force ◽  
Multi Objective ◽  
High Rise ◽  
High Rise Building ◽  
Mass Damper ◽  
Damper Design

In engineering applications, many control devices have been developed to reduce the vibrations of structures. Active tuned mass damper system is one of these devices, which is a combination of a passive tuned mass damper system and an actuator to produce a control force. The main objective of this paper is to present a practical procedure for both deterministic and probabilistic design of the active tuned mass damper control system using multi-objective genetic algorithms to mitigate high-rise building responses. For this purpose, extensive numerical analyses have been performed, and optimal robust results of the active tuned mass damper design parameters with their effectiveness in reducing the example building responses have been presented. Uncertainties, which may exist in the system, have been taken into account using a robust design optimization procedure. The stiffness matrix and damping ratio of the building are considered as uncertain random variables; and using the well-known beta distribution, 50 pairs of these variables are generated. This resulted in 50 buildings with different stiffness matrices and damping ratios. These simulated buildings are used to evaluate robust optimal values of the active tuned mass damper design parameters. Four non-commensurable objective functions, namely maximum displacement, maximum velocity, maximum acceleration of each floor of the building, and active control force produced by the actuator are considered, and a fast and elitist non-dominated sorting genetic algorithm approach is used to find a set of pareto-optimal solutions.

scholarly journals The Legality of Small Arms Production

2020 ◽  
Vol 1 ◽  
pp. 91-107
Author(s):  
Nicola Piccini
Keyword(s):  
Mass Production ◽  
A Priori ◽  
Manufacturing Industries ◽  
Effective Control ◽  
Control Mechanisms ◽  
Trade Restrictions ◽  
Small Arms ◽  
Commercial Viability ◽  
Intended Purpose ◽  
Arms Trade

Officially, international control of small arms and light weapons (SALW) has made considerable advancements in recent years, most notably in the form of the 2014 Arms Trade Treaty (ATT). Nonetheless, important systemic and structural deficiencies seem to persist, which prevent these control mechanisms from achieving their intended purpose. In an attempt to find an explanation for these shortcomings, this article traces back previous attempts aimed at combatting the illicit proliferation of SALW, by emphasising both their unbowed demand and the trade’s continuous commercial viability. The example of Bulgarian-made AK-47 machineguns underlines the picture of a system intentionally failing to prevent the weapons’ profitable export. It concludes that following the rise of globalisation, the privatisation of SALW manufacturing industries appears to have become the biggest impediment to effective control. Subsequently, it is argued that most anti-proliferation treaties are deliberately limited to a priori insufficient trade restrictions, as they lack any pre-emptive measures that target these weapons’ mass production in the first place. Once produced, SALW will find a buyer – no matter the existence of trade restrictions.

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