This study presents alternative approaches for the improvement of crash energy absorption in representative automobile crashworthy structures. One such approach is the use of configurable crush initiators introduced t...
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ISBN:
(纸本)9783319094106
This study presents alternative approaches for the improvement of crash energy absorption in representative automobile crashworthy structures. One such approach is the use of configurable crush initiators introduced through localized heating in tubular structures. The main objective is to improve the ability to absorb impact energy in a progressive and controlled manner by a local modification of material properties. In this manner, associated with the softening of the aluminium alloy, the deformation can be introduced precisely, forcing the tubular structure to deform in a mode of high energy absorption and reducing the maximum load in a controlled manner. An alternative approach for controllable energy absorption consists in the internal pressurization of structures in the framework of a crash-adaptive response. Within this strategy, the effect of internal pressurization of tubular structures in a crashworthiness application is investigated. The concept of internal pressurization can be implemented as a crash-adaptive structure therefore allowing different responses according to the intensity of shock.
Local damage detection in rotating machinery can become a very difficult issue due to time-varying load or presence of another damage reflected in amplitude modulation of the raw vibration signal. In this paper a two-...
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ISBN:
(纸本)9783319099170
Local damage detection in rotating machinery can become a very difficult issue due to time-varying load or presence of another damage reflected in amplitude modulation of the raw vibration signal. In this paper a two-stage filtering method is presented to deal with this problem. The first stage is based on autoregressive (AR) modeling. It is incorporated to suppress high-energy components that mask an informative signal. High-energy amplitudes of mesh harmonics modulated by other damage or load variation can affect selectors of optimal frequency band as well, so they have to be suppressed. The second stage relies on filtering the AR-residual signal using a linear filter based on an informative frequency band selector. Here as a selector we propose to use the average horizontal distance on quantile-quantile plot. We compare the result of the second stage with the spectral kurtosis. The procedure is illustrated by real data analysis of a two-stage gearbox used in a belt conveyor drive system in an open-pit mine.
This paper discusses the notion of operationmode in parallel manipulators with less than six dof. This notion has been reported recently in several papers but the physical meaning of an operation mode is not always cl...
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ISBN:
(纸本)9783319107233;9783319107226
This paper discusses the notion of operationmode in parallel manipulators with less than six dof. This notion has been reported recently in several papers but the physical meaning of an operation mode is not always clear. Indeed, even if in some cases an operation mode can be associated with an understandable motion type e.g., three pure translations or a spherical motion, in some other cases, such an association is not straightforward. Therefore, the axodes are used in this paper to characterize any operation mode of lower-mobility parallel manipulators. A 3-RPS manipulator is used as an illustrative example. This manipulator is special because one can parameterize its operation modes.
Rigidity detection is a very important tool for structural synthesis of mechanisms and the processing of CAD-generated models, as it helps to unveil possible sources of inconsistency in Grubler's count of degrees ...
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ISBN:
(纸本)9783319094106
Rigidity detection is a very important tool for structural synthesis of mechanisms and the processing of CAD-generated models, as it helps to unveil possible sources of inconsistency in Grubler's count of degrees of freedom(DOF) and thus to generate consistent kinematical models of complex mechanisms. This paper proposes a loop-based rigidity detection algorithm that is able to detect rigidity/mobility for special cases including multiple spherical-spherical pairs, such as the famous "double-banana" mechanism. To this end, the algorithm tracks "isolated" DOFs which are split into "fully isolated" and "transmitted isolated" DOFs. Using the independent loops as the basic building blocks, the kinematical network and its reduced loop connection graph are obtained, from which rigid sub-systems and the inherent "global" isolated rotational DOFs are recognized. The procedure is explained for the "double-banana" mechanism but is easily extended to other mechanisms.
This paper presents the topics, methods and objectives of a new lecture on CAD-integrated kinematic design of linkages for master students. The contents enable students in mechanical engineering to analyze and synthes...
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ISBN:
(纸本)9783319094106
This paper presents the topics, methods and objectives of a new lecture on CAD-integrated kinematic design of linkages for master students. The contents enable students in mechanical engineering to analyze and synthesize structures kinematically using advanced software tools such as numerical and algebraic computation software as well as 3D solid modeler. The structures range from 1-DOF mechanisms up to multi-DOF serial and parallel linkages. Using a generalized nomenclature and vector-matrix-based formulation of the geometry and kinematics of the systems, students are enabled to design both planar and spatial structures. The major objective is to provide the techniques and foundations for task specific synthesis and analysis of linkages with a strong focus on practical applications, which is demonstrated in an example design session in this paper.
This paper introduces a four degree-of-freedom parallel robot producing three translation and one rotation (Schonflies motion). This robot can generate a rectangular workspace that is close to the applicable work enve...
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ISBN:
(纸本)9783319181264;9783319181257
This paper introduces a four degree-of-freedom parallel robot producing three translation and one rotation (Schonflies motion). This robot can generate a rectangular workspace that is close to the applicable work envelope and suitable for pick-and-place operations. The kinematics of the robot is studied to analyze the workspace and the isocontours of the local dexterity over the representative regular workspace are visualized. The simplified dynamics is modeled and compared with Adams model to show its effectiveness.
Considered here is the effect of multistage coupling on the dynamics of an aircraft engine rotor with eight mistuned bladed discs on a drum-disc shaft. Each bladed disc had a different number of rotor blades. Free vib...
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ISBN:
(纸本)9783319107233;9783319107226
Considered here is the effect of multistage coupling on the dynamics of an aircraft engine rotor with eight mistuned bladed discs on a drum-disc shaft. Each bladed disc had a different number of rotor blades. Free vibrations were examined using finite element models of single rotating blades, bladed discs, and an entire rotor. In this study, the global rotating mode shapes of flexible mistuned bladed discs-shaft assemblies were calculated, taking into account rotational effects, such as centrifugal stiffening. The thus obtained natural frequencies of the blades, the shaft, bladed discs, and the entire shaft with discs were carefully examined and compared with a tuned system to discover resonance conditions and coupling effects. Mistuning caused considerably more intensive multistage coupling than the tuned system and distorted the mode shape nodal diameters.
The worldwide incidence of asthma yields 250,000 deaths annually, being almost all of these deaths avoidable. The inhalation therapy is the preferable route to deliver bronchodilator/anti-inflammatory drugs to the pat...
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ISBN:
(纸本)9783319094106
The worldwide incidence of asthma yields 250,000 deaths annually, being almost all of these deaths avoidable. The inhalation therapy is the preferable route to deliver bronchodilator/anti-inflammatory drugs to the patient lungs. Within this route of treatment, pressurized Metered Dose Inhalers (pMDI's) are the cornerstone devices. When coupled with a Valved Holding Chamber (VHC), its efficiency increases and the limitations almost vanish. The VHC devices efficiency is something of interest to measure. For that, it is necessary an experimental setup that evaluates the amount of drug delivered by the device. This setup shall replicate a human breath waveform as input, therefore a breath simulator machine was build. The report herein describes the project process of the form-closed cam-follower mechanism necessary to replicate the waveform. The design and dimensional constrains are input in the cam design, leading to a piston diameter of 63.0 mm and a cam base diameter of 250.0 mm. A performance analysis to the pressure angle, curvature radius and backlash impact force, is reported. It can be concluded that a larger diameter would improve the performance results substantially.
One of the applications of haptic technology is in education and training. Handwriting for first year-elementary students has been included in the curriculum for some years in Turkey as the first and only writing skil...
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ISBN:
(数字)9783319170671
ISBN:
(纸本)9783319170671;9783319170664
One of the applications of haptic technology is in education and training. Handwriting for first year-elementary students has been included in the curriculum for some years in Turkey as the first and only writing skill to be taught. Providing these students with a haptic assistance device during the handwriting learning process is the global aim of this work. Among the other components of the design such as electronics, controls and communication, mechanism design is a critical component to be considered for optimization of the device at different levels. This paper aims to address a solution to meet the design criteria through ergonomic design for user along with optimized force exertion capabilities.
It is difficult to find a comprehensive classification containing all aspects of robots, not to mention of micromanipulators, in present literature. With the focus on design and kinematic attributes, the objective of ...
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ISBN:
(纸本)9783319158624;9783319158617
It is difficult to find a comprehensive classification containing all aspects of robots, not to mention of micromanipulators, in present literature. With the focus on design and kinematic attributes, the objective of this paper is to create a classification of robots which can also be applied for micromanipulators. The different attributes are identified and discussed. Existing micromanipulators are grouped according to this classification scheme and a clear overview of their specific structural characteristics and performance is given. Thus three different groups of micromanipulators can be identified.
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