scholarly journals Effect of Different Design Parameters on the Cyclic Response of Reduced Beam Sections (RBS) Moment Connections

2021 ◽  
Author(s):  
Syed Asad Abbus Naqvi
Keyword(s):  
Sensitivity Analysis ◽  
Statistical Design ◽  
Fractional Factorial ◽  
Design Parameters ◽  
Dissipated Energy ◽  
Northridge Earthquake ◽  
Initial Stiffness ◽  
Moment Connections ◽  
Cyclic Response ◽  
Rbs Connections

After the 1994 Northridge earthquake, research has been conducted to develop new types of beamcolumn moment connections, such as Reduced Beam Section (RBS) connections. This study performs a sensitivity analysis of the cyclic response of RBS connections using detailed finite element simulation. The significance of the effect of twenty-one factors is assessed using a statistical design of experiment method. The input factors are related to the material properties or the geometry of the beam-column connection. A two-level fractional factorial design is used to create factor combinations for the sensitivity analysis. The cyclic response of RBS connections is assessed in terms of five response variables, including: the total dissipated energy, initial stiffness, strength degradation rate, maximum moment capacity and rupture index at 7.5% storey drift. The sensitivity analysis results show that the beam depth has the greatest influence on the cyclic response of RBS connections.

scholarly journals Effect of Different Design Parameters on the Cyclic Response of Reduced Beam Sections (RBS) Moment Connections

2021 ◽  
Author(s):  
Syed Asad Abbus Naqvi
Keyword(s):  
Sensitivity Analysis ◽  
Statistical Design ◽  
Fractional Factorial ◽  
Design Parameters ◽  
Dissipated Energy ◽  
Northridge Earthquake ◽  
Initial Stiffness ◽  
Moment Connections ◽  
Cyclic Response ◽  
Rbs Connections

After the 1994 Northridge earthquake, research has been conducted to develop new types of beamcolumn moment connections, such as Reduced Beam Section (RBS) connections. This study performs a sensitivity analysis of the cyclic response of RBS connections using detailed finite element simulation. The significance of the effect of twenty-one factors is assessed using a statistical design of experiment method. The input factors are related to the material properties or the geometry of the beam-column connection. A two-level fractional factorial design is used to create factor combinations for the sensitivity analysis. The cyclic response of RBS connections is assessed in terms of five response variables, including: the total dissipated energy, initial stiffness, strength degradation rate, maximum moment capacity and rupture index at 7.5% storey drift. The sensitivity analysis results show that the beam depth has the greatest influence on the cyclic response of RBS connections.

Mathematical Modelling of the Rear Drive Unit of a Lightweight Vehicle for Sensitivity Analysis of Vibration

2016 ◽  
Author(s):  
Jiewei Lin ◽  
Yi Qiu
Keyword(s):  
Mathematical Model ◽  
Adverse Effect ◽  
Sensitivity Analysis ◽  
Vertical Vibration ◽  
Fractional Factorial ◽  
Design Stage ◽  
Design Parameters ◽  
Mass Reduction ◽  
Drive Unit ◽  
Car Body

Lightweight technology is applied in the automobile industry because mass reduction is beneficial in improving fuel efficiency and reducing CO2 emissions. Apart from the car body and the power unit (the two heaviest parts of a vehicle), the driveline also has potential for a reduction in weight. The driveline transfers power to the wheels and plays an important role in the vehicle system. Vibration is induced by the road input and by unbalanced forces transmitted through the driveline to the car body. Mass reduction in the driveline could influence the dynamic behaviour of a vehicle but it is not yet clear how mass reduction affects vibration of the driveline, the vehicle ride and NVH performance — important considerations when designing a lightweight driveline. In the prototype design stage, a mathematical model provides a more flexible and less costly method of optimising the system dynamics. In this paper, a 14 degree-of-freedom mathematical model is developed to study the dynamics of a rear drive unit (RDU). The system consists of a rear differential gearbox, left and right constant velocity joints and driveshafts, a rear sub-frame, and bushings between the RDU and the sub-frame and between the sub-frame and the car body. Excitations from the rear wheels, rear suspensions, and input shaft were considered. The vertical acceleration at the rear sub-frame was calculated and correlated with a calibrated multi-body dynamic model of the vehicle developed in a parallel study. Using a fractional factorial design with the vehicle travelling on a smooth road at various speeds, a sensitivity analysis was carried out with the developed mathematical model to identify the contributions of the mass properties of the RDU and the bushing parameters to the vibration at the centre of gravity (COG) of the rear sub-frame. Results indicate that the effects of design parameters on the rear sub-frame vibration vary according to the vehicle speed. For vibration at the rear sub-frame, the most influential factors are the masses of the rear differential gearbox and the driveshaft, and the stiffness of the front right bushings between the RDU and the sub-frame. The stiffness of the front left bushing between the RDU and the sub-frame also has considerable effect on the subsystem response but only at higher speeds. Reducing the mass of the CV joint is beneficial in decreasing the vertical vibration at the COG of the rear sub-frame, while reductions in masses of the gearbox and the driveshafts tend to slightly increase the vertical vibration at the same location. However, the adverse effect brought by lightweight differential gearbox and driveshafts on vibration is relatively small that may be hardly detected by passengers. The adverse effect (if any) can be compromised by adjusting the stiffness of the front bushings between the gearbox and the sub-frame.

Sensitivity Analysis of Ballistics Performance with Respect to Statistical Design Parameters

2011 ◽  
Vol 130-134 ◽  
pp. 373-376
Author(s):  
Chang Qing Liu ◽  
Wen Cai Luo
Keyword(s):  
Sensitivity Analysis ◽  
Statistical Design ◽  
Statistical Characteristics ◽  
Design Parameters ◽  
Statistical Parameters ◽  
Baseline Design ◽  
Flight Range ◽  
Sensitivity Derivatives ◽  
Performance Results ◽  
Sensitive Parameters

To investigate the effect of design parameters with statistical characteristics on ballistics performance, sensitivity analysis of the flight range objective with respect to relevant parameters was conducted to demonstrate it. Statistical parameters were modeled using an iterative method in order to determine descriptive statistics for further sampling. Simulation of flight range based on a dynamics model was then carried out. Finally, sensitivity derivatives from the baseline design scheme were calculated to locate the most sensitive parameters which can be controlled specially for better performance. Results show that by sensitivity analysis, thrust parameters affect the flight range objective obviously while others not, which provides suggestions about whether some parameters should be limited in a range or not.

scholarly journals CONCEPTUAL DESIGN FOR ASSEMBLY IN AEROSPACE INDUSTRY: SENSITIVITY ANALYSIS OF MATHEMATICAL FRAMEWORK AND DESIGN PARAMETERS

2021 ◽  
Vol 1 ◽  
pp. 731-740
Author(s):  
Giovanni Formentini ◽  
Claudio Favi ◽  
Claude Cuiller ◽  
Pierre-Eric Dereux ◽  
Francois Bouissiere ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Conceptual Design ◽  
Design Parameters ◽  
Design For Assembly ◽  
Mathematical Framework ◽  
Commercial Aircraft ◽  
System Architectures ◽  
Complex Engineering ◽  
Aircraft System ◽  
Definition Of

AbstractOne of the most challenging activity in the engineering design process is the definition of a framework (model and parameters) for the characterization of specific processes such as installation and assembly. Aircraft system architectures are complex structures used to understand relation among elements (modules) inside an aircraft and its evaluation is one of the first activity since the conceptual design. The assessment of aircraft architectures, from the assembly perspective, requires parameter identification as well as the definition of the overall analysis framework (i.e., mathematical models, equations).The paper aims at the analysis of a mathematical framework (structure, equations and parameters) developed to assess the fit for assembly performances of aircraft system architectures by the mean of sensitivity analysis (One-Factor-At-Time method). The sensitivity analysis was performed on a complex engineering framework, i.e. the Conceptual Design for Assembly (CDfA) methodology, which is characterized by level, domains and attributes (parameters). A commercial aircraft cabin system was used as a case study to understand the use of different mathematical operators as well as the way to cluster attributes.

Tolerance Analysis of a Robot Manipulator Having Uncertainties in Joint Clearance and Axis Orientation

2007 ◽  
Author(s):  
Dong Hwan Choi ◽  
Se Jeong Lee ◽  
Jonathan A. Wickert ◽  
Hong Hee Yoo
Keyword(s):  
Robot Manipulator ◽  
Statistical Design ◽  
Tolerance Analysis ◽  
Joint Clearance ◽  
Design Parameters ◽  
Positional Error ◽  
Link Length ◽  
Axis Orientation ◽  
Manufacturing Tolerances ◽  
Clearance Model

The operating positional error of a robot manipulator, which develops inevitably because of manufacturing tolerances and assembly clearances, is preferentially maintained within a certain range in order to achieve an acceptable level of performance and accuracy. Because additional cost is incurred when manufacturing tolerances are tightened, an alternative design strategy maximizes the tolerances (so as to reduce the cost) while minimizing positioning error (to satisfy a performance requirement). In this paper, a new joint clearance model is developed for spatial mechanisms that incorporate revolute joints, which in turn are subjected to specified tolerance or uncertainty in the orientation of their axes. Statistical design parameters related to variations of link length and joint axis orientation are identified from the clearance model. The statistical influence of the design parameters on the robot manipulator’s response is investigated through a general multibody dynamics sensitivity formulation. The method offers substantial improvement in computational efficiency when compared to the Monte Carlo procedure. The uncertainty in orientation of a revolute joint’s axis influences the positioning accuracy of the robot manipulator’s response to a greater degree than does uncertainty in the length of a link.

Life Augmentation of Turbine Exhaust System Compensators Through Integrated MADM Optimization Approach of Stress Based Fatigue Cycles

2021 ◽  
Author(s):  
Nitin D. Pagar ◽  
Amit R. Patil
Keyword(s):  
Exhaust System ◽  
Optimization Methods ◽  
Fractional Factorial ◽  
Design Parameters ◽  
Optimization Approach ◽  
Auxiliary Equipment ◽  
Maximum Expansion ◽  
Optimal Configurations ◽  
Selection Of ◽  
Turbine Exhaust

Abstract Exhaust expansion joints, also known as compensators, are found in a variety of applications such as gas turbine exhaust pipes, generators, marine propulsion systems, OEM engines, power units, and auxiliary equipment. The motion compensators employed must have accomplished the maximum expansion-contraction cycle life while imposing the least amount of stress. Discrepancies in the selecting of bellows expansion joint design parameters are corrected by evaluating stress-based fatigue life, which is challenging owing to the complicated form of convolutions. Meridional and circumferential convolution stress equations that influencing fatigue cycles are evaluated and verified with FEA. Fractional factorial Taguchi L25 matrix is used for finding the optimal configurations. The discrete design parameters for the selection of the suitable configuration of the compensators are analysed with the help of the MADM decision making techniques. The multi-response optimization methods GRA, AHP, and TOPSIS are used to determine the parametric selection on a priority basis. It is seen that weighing distribution among the responses plays an important role in these methods and GRA method integrated with principal components shows best optimal configurations. Multiple regression technique applied to these methods also shows that PCA-GRA gives better alternate solutions for the designer unlike the AHP and TOPSIS method. However, higher ranked Taguchi run obtained in these methods may enhance the suitable selection of different design configurations. Obtained PCA-GRG values by Taguchi, Regression and DOE are well matched and verified for the all alternate solutions. Further, it also shows that stress based fatigue cycles obtained in this analysis for the L25 run indicates the range varying from 1.13 × 104 cycles to 9.08 × 105 cycles, which is within 106 cycles. This work will assist the design engineer for selecting the discrete parameters of stiff compensators utilized in power plant thermal appliances.

Direct Sensitivity Analysis of Spatial Multibody Systems With Joint Friction Using Index-1 Formulation

2021 ◽  
Author(s):  
Adwait Verulkar ◽  
Corina Sandu ◽  
Daniel Dopico ◽  
Adrian Sandu
Keyword(s):  
Sensitivity Analysis ◽  
Dynamic Systems ◽  
Multibody Systems ◽  
Friction Model ◽  
Design Parameters ◽  
Adjoint Sensitivity ◽  
Joint Friction ◽  
Multibody Dynamic ◽  
Model Dynamics ◽  
Direct Sensitivity

Abstract Sensitivity analysis is one of the most prominent gradient based optimization techniques for mechanical systems. Model sensitivities are the derivatives of the generalized coordinates defining the motion of the system in time with respect to the system design parameters. These sensitivities can be calculated using finite differences, but the accuracy and computational inefficiency of this method limits its use. Hence, the methodologies of direct and adjoint sensitivity analysis have gained prominence. Recent research has presented computationally efficient methodologies for both direct and adjoint sensitivity analysis of complex multibody dynamic systems. The contribution of this article is in the development of the mathematical framework for conducting the direct sensitivity analysis of multibody dynamic systems with joint friction using the index-1 formulation. For modeling friction in multibody systems, the Brown and McPhee friction model has been used. This model incorporates the effects of both static and dynamic friction on the model dynamics. A case study has been conducted on a spatial slider-crank mechanism to illustrate the application of this methodology to real-world systems. Using computer models, with and without joint friction, effect of friction on the dynamics and model sensitivities has been demonstrated. The sensitivities of slider velocity have been computed with respect to the design parameters of crank length, rod length, and the parameters defining the friction model. Due to the highly non-linear nature of friction, the model dynamics are more sensitive during the transition phases, where the friction coefficient changes from static to dynamic and vice versa.

Direct Sensitivity Analysis of Multibody Systems: A Vehicle Dynamics Benchmark

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Alfonso Callejo ◽  
Daniel Dopico
Keyword(s):  
Sensitivity Analysis ◽  
Multibody Systems ◽  
Automatic Differentiation ◽  
Time Integration ◽  
General Purpose ◽  
Contact Forces ◽  
Design Parameters ◽  
Computational Techniques ◽  
Computationally Efficient ◽  
Integration Algorithm

Algorithms for the sensitivity analysis of multibody systems are quickly maturing as computational and software resources grow. Indeed, the area has made substantial progress since the first academic methods and examples were developed. Today, sensitivity analysis tools aimed at gradient-based design optimization are required to be as computationally efficient and scalable as possible. This paper presents extensive verification of one of the most popular sensitivity analysis techniques, namely the direct differentiation method (DDM). Usage of such method is recommended when the number of design parameters relative to the number of outputs is small and when the time integration algorithm is sensitive to accumulation errors. Verification is hereby accomplished through two radically different computational techniques, namely manual differentiation and automatic differentiation, which are used to compute the necessary partial derivatives. Experiments are conducted on an 18-degree-of-freedom, 366-dependent-coordinate bus model with realistic geometry and tire contact forces, which constitutes an unusually large system within general-purpose sensitivity analysis of multibody systems. The results are in good agreement; the manual technique provides shorter runtimes, whereas the automatic differentiation technique is easier to implement. The presented results highlight the potential of manual and automatic differentiation approaches within general-purpose simulation packages, and the importance of formulation benchmarking.

Design Sensitivity Analysis of Nonlinear Multidisciplinary Multibody Systems in the MIXEDMODELS Platform

2007 ◽  
Author(s):  
Shilpa A. Vaze ◽  
Prakash Krishnaswami ◽  
James DeVault
Keyword(s):  
Sensitivity Analysis ◽  
Multibody Systems ◽  
Design Sensitivity ◽  
Differential Algebraic Equations ◽  
The State ◽  
Design Sensitivity Analysis ◽  
Design Parameters ◽  
State Variables ◽  
Sensitivity Coefficients ◽  
Design Variables

Most state-of-the-art multibody systems are multidisciplinary and encompass a wide range of components from various domains such as electrical, mechanical, hydraulic, pneumatic, etc. The design considerations and design parameters of the system can come from any of these domains or from a combination of these domains. In order to perform analytical design sensitivity analysis on a multidisciplinary system (MDS), we first need a uniform modeling approach for this class of systems to obtain a unified mathematical model of the system. Based on this model, we can derive a unified formulation for design sensitivity analysis. In this paper, we present a modeling and design sensitivity formulation for MDS that has been successfully implemented in the MIXEDMODELS (Multidisciplinary Integrated eXtensible Engine for Driving Metamodeling, Optimization and DEsign of Large-scale Systems) platform. MIXEDMODELS is a unified analysis and design tool for MDS that is based on a procedural, symbolic-numeric architecture. This architecture allows any engineer to add components in his/her domain of expertise to the platform in a modular fashion. The symbolic engine in the MIXEDMODELS platform synthesizes the system governing equations as a unified set of non-linear differential-algebraic equations (DAE’s). These equations can then be differentiated with respect to design to obtain an additional set of DAE’s in the sensitivity coefficients of the system state variables with respect to the system’s design variables. This combined set of DAE’s can be solved numerically to obtain the solution for the state variables and state sensitivity coefficients of the system. Finally, knowing the system performance functions, we can calculate the design sensitivity coefficients of these performance functions by using the values of the state variables and state sensitivity coefficients obtained from the DAE’s. In this work we use the direct differentiation approach for sensitivity analysis, as opposed to the adjoint variable approach, for ease in error control and software implementation. The capabilities and performance of the proposed design sensitivity analysis formulation are demonstrated through a numerical example consisting of an AC rectified DC power supply driving a slider crank mechanism. In this case, the performance functions and design variables come from both electrical and mechanical domains. The results obtained were verified by perturbation analysis, and the method was shown to be very accurate and computationally viable.

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