Design of lightweight wooden floors to avoid human discomfort

1988 ◽  
Vol 15 (2) ◽  
pp. 254-262 ◽  
Author(s):  
Ian Smith ◽  
Ying Hei Chui
Keyword(s):  
Natural Frequencies ◽  
Design Method ◽  
Economic Cost ◽  
Dynamical Behaviour ◽  
Design Solution ◽  
Tolerance Design ◽  
Mean Square ◽  
User Perception ◽  
Forcing Function ◽  
Domestic Setting

This paper gives "designer usable" methods for predicting the dynamical behaviour of lightweight wood-joist floors covered with semirigidly attached wood-based sheathings of materials such as plywood or waferboard. Included are methods for predicting natural frequencies and root-mean-square (rms) acceleration under a defined forcing function. It is proposed that this rms acceleration be the criterion for estimating user perception based tolerance of a projected design solution in the domestic setting. Case studies suggest that the economic cost of producing more rational designs is small. Consideration is, at this stage, limited to floors that are rectangular in plan and contain no openings nor intermediate support partitions. Suggestions are made as to methods of building floors with acceptable vibrational performances, together with recommendations for further research. Key words: floors, wood, vibrations, human tolerance, design method.

PNEUMATIC VIBROISOLATION SYSTEM OF THE BASE DESK WITH NATURAL FREQUENCY REGULATION

2021 ◽  
Vol 113 ◽  
pp. 91-100
Author(s):  
Radka JÍROVÁ ◽  
Lubomír PEŠÍK
Keyword(s):  
Natural Frequency ◽  
Automotive Industry ◽  
Natural Frequencies ◽  
Dynamical Behaviour ◽  
Operating Conditions ◽  
Frequency Regulation ◽  
The Stability ◽  
Short Time

Vibroisolation systems of base desks for machine and testing facilities usually cannot effect efficient changing of their own frequencies according to operating conditions. Especially in the case of the automotive industry, the possibility of changing natural frequencies is very desirable. During varying operating conditions, the vibroisolation system needs to be regulated easily and quickly regarding the minimisation of dynamical forces transmitted to the ground and to ensure the stability of the testing process. This paper describes one of the options of tuning the base desk at a relatively short time and by sufficient change of own frequencies, which decides the dynamical behaviour of the whole system.

CAFixD: A Case-Based Reasoning Fixture Design Method. Framework and Indexing Mechanisms

2005 ◽  
Vol 6 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Iain M. Boyle ◽  
Kevin Rong ◽  
David C. Brown
Keyword(s):  
Design Method ◽  
Critical Issue ◽  
Design Solution ◽  
Case Based Reasoning ◽  
Fixture Design ◽  
Functional Requirements ◽  
Rigorous Approach ◽  
Machining Operations ◽  
Case Based ◽  
Individual Requirement

Fixtures accurately locate and secure a part during machining operations. Various computer-aided fixture design (CAFD) methods have been developed to reduce design costs associated with fixturing. One approach uses a case-based reasoning (CBR) method where relevant design experience is retrieved from a design library and adapted to provide a new design solution. Indexing design cases is a critical issue in CBR, and CBR systems can suffer from an inability to distinguish between cases if indexing is inadequate. This paper presents CAFixD, a CAFD methodology that adopts a rigorous approach to defining indexing attributes based upon axiomatic design functional requirement decomposition. A design requirement is decomposed in terms of functional requirements, physical solutions are retrieved and adapted for each individual requirement, and the design is then reconstituted to form a complete fixture design. This paper presents the CAFixD framework and operation, and discusses in detail the indexing mechanisms used.

Mean-Square Response of a Second-Order System to Nonstationary, Random Excitation

1970 ◽  
Vol 37 (3) ◽  
pp. 612-616 ◽  
Author(s):  
L. L. Bucciarelli ◽  
C. Kuo
Keyword(s):  
Narrow Band ◽  
Random Excitation ◽  
Second Order ◽  
Envelope Function ◽  
Order System ◽  
Mean Square ◽  
Forcing Function ◽  
Mean Square Response ◽  
Noise Function ◽  
The Mean

The mean-square response of a lightly damped, second-order system to a type of non-stationary random excitation is determined. The forcing function on the system is taken in the form of a product of a well-defined, slowly varying envelope function and a noise function. The latter is assumed to be white or correlated as a narrow band process. Taking advantage of the slow variation of the envelope function and the small damping of the system, relatively simple integrals are obtained which approximate the mean-square response. Upper bounds on the mean-square response are also obtained.

A Unified Frequency Equation and the Motion Analysis of a Moving Flexible Beam Carrying a Concentrated Mass

1999 ◽  
Author(s):  
S. Park ◽  
J. W. Lee ◽  
Y. Youm ◽  
W. K. Chung
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Frequency Equation ◽  
Open Loop ◽  
Mode Shapes ◽  
Flexible Beam ◽  
Lumped Mass ◽  
Concentrated Mass ◽  
Forcing Function ◽  
The Mathematical Model

Abstract In this paper, the mathematical model of a Bernoulli-Euler cantilever beam fixed on a moving cart and carrying an intermediate lumped mass is derived. The equations of motion of the beam-mass-cart system is analyzed utilizing unconstrained modal analysis, and a unified frequency equation which can be generally applied to this kind of system is obtained. The change of natural frequencies and mode shapes with respect to the change of the mass ratios of the beam, the lumped mass and the cart and to the position of the lumped mass is investigated. The open-loop responses of the system by arbitrary forcing function are also obtained through numerical simulations.

scholarly journals A Hybrid Tolerance Design Method for the Active Phased-Array Antenna

2020 ◽  
Vol 10 (4) ◽  
pp. 1435 ◽  
Author(s):  
Guodong Sa ◽  
Zhenyu Liu ◽  
Chan Qiu ◽  
Jianrong Tan
Keyword(s):  
Design Method ◽  
Array Antenna ◽  
Tolerance Design ◽  
Geometric Errors ◽  
Discrete Elements ◽  
Phased Array Antenna ◽  
Form Errors ◽  
Position Errors ◽  
Working Frequency ◽  
Effectiveness And Efficiency

With the increase of the working frequency of the array antenna, tolerance design has become increasingly important. The state-of-art tolerance design methods mainly deal with the position tolerance of the discrete elements. However, the geometric errors of the whole array have resulted from two aspects: (1) the position errors of the discrete elements and (2) the form errors of the continuous reflection plate. To optimize the position tolerance and flatness simultaneously, a hybrid tolerance design method is proposed. First, the relation between the performance of the array antenna and hybrid tolerances was determined based on the second order Taylor expansion. Then the expectation and variance of the performance were derived. Finally, the hybrid tolerances were optimized and the performance of the antenna was improved. Simulation results proved the effectiveness and efficiency of the proposed hybrid tolerance design method.

scholarly journals Assembly Tolerance Design Based on Skin Model Shapes Considering Processing Feature Degradation

2019 ◽  
Vol 9 (16) ◽  
pp. 3216 ◽  
Author(s):  
Ci He ◽  
Shuyou Zhang ◽  
Lemiao Qiu ◽  
Xiaojian Liu ◽  
Zili Wang
Keyword(s):  
Design Method ◽  
Joint Probability ◽  
Joint Probability Distribution ◽  
Manufacturing Cost ◽  
Tolerance Design ◽  
Sampling Point ◽  
Skin Model ◽  
Machined Surface ◽  
Assembly Tolerance ◽  
Five Axis

To increase the reliability and accuracy of tolerance design, more and more research works are considering not only orientation and position deviations; they are also forming errors in tolerance modeling. As a direct cause of form errors in industrial mass production, the processing features of the machining system degrade over time. Under the Industry 4.0 paradigm, an assembly tolerance design method based on Skin Model Shape is proposed to take the effect of degrading processing features into consideration. A continuous-time multi-dimensional Markov process is trained through maximum likelihood estimation based on the nodal sampling point set on the machined surface. Degradation of the machined surface is modeled based on the joint probability distribution of nodal displacements. Assembly force constraints and assembly entity constraints are applied to spatial assembly simulations. Tolerance synthesis takes the manufacturing cost and assembling probability as design objectives. A design example of the rotary feed component in a five-axis machine tool is proposed for explanation and verification.

Dynamical Behaviour of a Materially Damped Flexible Towed Cable

1972 ◽  
Vol 23 (2) ◽  
pp. 109-120 ◽  
Author(s):  
T C Cannon ◽  
J Genin
Keyword(s):  
Closed Form ◽  
Natural Frequencies ◽  
Equilibrium Shape ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Dynamical Behaviour ◽  
Aerodynamic Loading ◽  
Towed Cable ◽  
Closed Form Approximation ◽  
Good Agreement

SummaryThe three-dimensional equations of motion of a flexible towed cable are developed. A closed-form approximation for the equilibrium shape of a cable subjected to arbitrary aerodynamic loading is developed and used in the study of a heavy, vibrating tow cable. Natural frequencies of vibration and cable shapes are computed for typical cables and are shown to be in good agreement with exact, numerically obtained values.

Dynamic Analysis of Structures with Interval Parameters under Stochastic Process Excitation

2014 ◽  
Vol 553 ◽  
pp. 699-704 ◽  
Author(s):  
Duy Minh Do ◽  
Wei Gao ◽  
Cheng Wei Yang ◽  
Chong Ming Song
Keyword(s):  
Stochastic Process ◽  
Particle Swarm Optimization ◽  
Dynamic Analysis ◽  
Optimization Algorithm ◽  
Natural Frequencies ◽  
Particle Swarm Optimization Algorithm ◽  
Particle Swarm ◽  
Mean Square ◽  
Structural Dynamic ◽  
Swarm Optimization

This paper presents the interval dynamic analysis of structures with uncertain-but-bounded parameters under stochastic process excitations. Structural natural frequencies and mean square values of structural random responses are not deterministic values but intervals. The interval problems are converted to optimization problems. Mathematical models are developed to find the bounds of interval natural frequencies and mean square displacements. An improved particle swarm optimization algorithm, namely lower sequence initialized high-order nonlinear particle swarm optimization algorithm, is employed to capture the exact bounds of structural dynamic characteristics and random vibration responses. Numerical example is used to demonstrate the presented method. Quasi-Monte Carlo simulations are also implemented to validate the change ranges of structural natural frequencies and mean square displacements produced by the proposed method.

A Robust Tolerance Design Method Based on Fuzzy Quality Loss

2006 ◽  
Vol 1 (1) ◽  
pp. 101-105 ◽  
Author(s):  
Yan-long Cao ◽  
Jian Mao ◽  
Jiang-xin Yang ◽  
Zhao-tong Wu ◽  
Li-qun Wu
Keyword(s):  
Design Method ◽  
Tolerance Design ◽  
Quality Loss
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