• Smart Structures and Systems
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• v.23 no.1
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• pp.15-29
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• 2019

This paper addresses the problem of damage detection in suspension bridge hangers, with an emphasis on the modal flexibility method. It aims at evaluating the capability and the accuracy of the modal flexibility method to detect and locate single and multiple damages in suspension bridge hangers, with different level of severity and various locations. The study is conducted numerically and experimentally on a laboratory suspension bridge mock-up. First, the covariance-driven stochastic subspace identification is used to extract the modal parameters of the bridge from experimental data, using only output measurements data from ambient vibration. Then, the method is demonstrated for several damage scenarios and compared against other classical methods, such as: Coordinate Modal Assurance Criterion (COMAC), Enhanced Coordinate Modal Assurance Criterion (ECOMAC), Mode Shape Curvature (MSC) and Modal Strain Energy (MSE). The paper demonstrates the relative merits and shortcomings of these methods which play a significant role in the damage detection ofsuspension bridges.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.135-142
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• 2008

This paper deals with the design of a robust PI controller for a vehicle suspension system. A method, which is related to computation of all stabilizing PI controllers, is applied to the vehicle suspension system in order to obtain optimum control between passenger comfort and driving performance. The PI controller parameters are calculated by plotting the stability boundary locus in the $(k_p,\;k_i)$-plane and illustrative results are presented. In reality, like all physical systems, the vehicle suspension system parameters contain uncertainty. Thus, the proposed method is also used to compute all the parameters of a PI controller that stabilize a vehicle suspension system with uncertain parameters.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.138-147
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• 2000

Vehicle suspension systems are parts which effect performances of a vehicle such as ride quality, handing characteristics, straight performance and steering effort etc. Kinematic design is a decision of joints` position for straight performance and steering effort. But, when vehicle is rebounding and bumping, chang of joints` displacement is nonlinear and a surmise of straight performance and steering effort at that joints` position is difficult. So design of suspension systems is done through a inefficient method of tried-and-error depending on designer`s experience. In this paper, kinematic design of suspension systems was done through the optimal design using a genetic algorithm. For this optimal design, the function for quantification of straight performance and steering effort was made, and the kinematic design method of suspension systems having this function as the objective function was suggested.

• Steel and Composite Structures
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• v.52 no.6
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• pp.695-711
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• 2024

Suspension bridges are critical to urban transportation, but those in earthquake-prone areas face unique challenges. In the event of a moderate or strong earthquake, conventional linear theory-based approaches for detecting bridge damage become inadequate. This study presents an efficient method for identifying damage in suspension bridges using time history nonlinear inelastic analysis. A practical advanced analysis program is employed to model cable-supported bridges with low computational cost, generating a dataset for four hybrid models: PSO-DT, PSO-RF, PSO-XGB, and PSO-CGB. These models combine decision tree (DT), random forest (RF), extreme gradient boosting (XGB), and categorical gradient boosting (CGB) with particle swarm optimization (PSO) to capture nonlinear correlations between displacement response and damage. Principal component analysis reduces dataset dimensions, and PSO selects the optimal model. A numerical case study of a suspension bridge under simulated earthquake conditions identifies PSO-XGB as the best model for predicting stiffness reduction. The results demonstrate the method's robustness for nonlinear damage detection in suspension bridges under earthquake excitation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.3
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• pp.184-190
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• 2015

NVH engineering has become a hot issue due to radical technology changes and development in automotive industry since customers' expectations and needs for their vehicle is taken to a higher level. However, the source identification and quantification of the road noise within a vehicle is still not at the level where it needs to be to meet their expectations due to its' complex transfer path and difficulties in path optimization. The primary focus of this research is on direct force obtaining method at suspension hard points using suspension test rig. Directly obtained forces at suspension to body mounting points are critical and crucial for determining the effects of design changes of the suspension has on road noise performance. Direct force obtaining method has its limitation in sensor installation within an actual vehicle therefore, many has been indirectly calculating forces using full matrix inversion method or dynamic stiffness method. In this study, to circumvent this limitation, a suspension rig is used. Then, the suspension rig is verified through a comparative analysis of its dynamic behavior between the actual vehicle by cleat test on chassis dynamometer.

• Smart Structures and Systems
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• v.12 no.6
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• pp.679-694
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• 2013

In this paper the application of the Interpolation Damage Detection Method to the numerical model of a suspension bridge instrumented with a network of Micro-Electro-Mechanical System sensors is presented. The method, which, in its present formulation, belongs to Level II damage identification method, can identify the presence and the location of damage from responses recorded on the structure before and after a seismic damaging event. The application of the method does not require knowledge of the modal properties of the structure nor a numerical model of it. Emphasis is placed herein on the influence of recorded signals noise on the reliability of the results given by the Interpolation Damage Detection Method. The response of a suspension bridge to seismic excitation is computed from a numerical model and artificially corrupted with random noise characteristic of two families of Micro-Electro-Mechanical System accelerometers. The reliability of the results is checked for different damage scenarios.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.115.3-115
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• 2002

To improve the performance of the tracked vehicle system, we examined the feasibility of using the preview control for the tracked vehicles suspension system. We proposed a method to apply a linear optimal preview control to the tracked vehicle system. To avoid the complexity of modeling the track subsystem and kinematical nonlinearity in the trailing arm suspension, we classified these as unknown dynamics and disturbances. We used the Time Delay Control(TDC) method to make sprung mass dynamics follow that of linear preview controlled tracked vehicle model by compensating the uncertainties and disturbances. We have verified by the computer simulation that the proposed method shows good robus...

• Journal of Industrial Technology
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• v.18
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• pp.233-240
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• 1998

In this study, ride sensitivity analysis of train with non-linear suspension elements is performed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train is parameterized. Equation of motion of the train model is derived, and using the direct differentiation method, sensitivity equations are obtained. For a nominal ride quality performance index, sensitivity analysis with respect to various design parameters regarding non-linear suspension parameters is carried out.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.24-31
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• 1995

This paper shows the fatigue durability test method for vehicle suspension systems. Durability should be assured for the safe driving during vehicle life cycle. A computer simulation for the vehicle dynamics was used to obtain dynamic loads that were required for the fatigue durability test. Durability tests were done for an Important load-carrying component of the suspension system. Stress analyses using stresscoat and strain gages were also done for the component. This study demonstrated an effective method for the fatigue durability test.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.113-118
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• 1997

This paper presents the dimensional synthesis and kinematic analysis of the RSCS-SSP motion generating spatial mechanism using the displacement matrix method. This type of spatial mechanisms is used for the Mcpherson suspension in small automobiles. It is modeled for the wheel bump/rebound and steering motion. First, the suspension is modeled as a multiloop spatial rigid body guidance mechanism for the two major motions. Then the design equations for SSP, RS, and SC strut links are applied to synthesize an RSCS-SSP for up to three prescribed positions for the steering motiom from the suspension design specification. Thus a RSCS-SSP mechanism which is synthesized is also analyzed for the displacement during the steering motion.