The Effect of Longitudinal Center of Gravity Position on the Sway Stability of a Small Cargo Trailer

2008 ◽  
Author(s):  
Michael G. Gilbert ◽  
Daniel A. Godrick ◽  
Richard H. Klein
Keyword(s):  
Dynamic Response ◽  
Damping Ratio ◽  
Leaf Spring ◽  
Loading Conditions ◽  
Novice Drivers ◽  
Training Requirements ◽  
Mandatory Training ◽  
Damping Characteristics ◽  
The Stability ◽  
The Impact

Small and mid-sized cargo trailers are often used to transport goods by people with limited experience in loading trailers and driving vehicles with trailers attached. This paper examines the effect of front to rear load position on the stability of a trailer by measuring its dynamic response to a variety of steer inputs at several different highway speeds. Additionally, tests with varying steers and speeds were performed with a simulated suspension malfunction to study the trailer’s dynamic response to this condition. Trailer sway has been a well-documented trailer characteristic for decades. However there are no special driver’s licensing or mandatory training requirements for even large trailers and campers. The trailer chosen for this test was a lightweight double axle cargo trailer commonly rented by people with limited to no towing experience. This consumer is likely to be unfamiliar with the best practices of trailer loading. This consumer is also likely a non-professional driver with little to no towing experience in the event of encountering unexpected trailer sway. Therefore it was the goal of the authors to determine how the stability of this type of trailer varies with different front to rear loading conditions and speeds to see if it is safe to operate on the highways by novice drivers. Trailer sway stability was determined by measuring the trailer sway (articulation) response during repeated, pulse steer tests. The trailer sway damping characteristics were measured, as a “damping ratio”, for six different hitch loads that corresponded to six different longitudinal loading conditions. These conditions, expressed as % load forward of the trailer centerline / % load aft of the trailer centerline were: 65/35, 60/40, 55/45, 50/50, 45/55, and 40/60. These loading conditions were tested per SAE J2664 [1] protocol. The resulting trailer sway characteristics for each loading condition then were compared to published trailer sway stability criteria [2, 3] to determine the suitability of this particular tow vehicle-trailer combination for use by the public in a rental market. The impact of a suspension malfunction on the trailer stability was also studied. This consisted of a detachment of one rear leaf spring hanger.

Application of SCES in Improving Dynamic Response of DC Microgrid Bus Voltage

2014 ◽  
Vol 521 ◽  
pp. 431-434
Author(s):  
Yuan Sheng Xiong ◽  
Jian Ming Xu
Keyword(s):  
Dynamic Response ◽  
Feedforward Control ◽  
Dc Microgrid ◽  
Wide Range ◽  
Supercapacitor Energy Storage ◽  
Response Performance ◽  
Dc Bus ◽  
Bus Voltage ◽  
The Stability ◽  
The Impact

To improve the stability of DC bus voltage in DC microgrid, and reduce the impact on microgrid equipments by the DC bus voltage fluctuations, a supercapacitor energy storage (SCES) is designed to connect to the DC bus by the bi-directional converter. The controller is designed by the feedforward control and proportional method with the deadband. The great load disturbance is simulated in PSIM software when the DC microgrid operates in the grid-connected rectification mode. The simulation results show that SCES under the proposed control strategy can reduce the fluctuation range of the DC bus voltage in a wide range of load disturbances, and the dynamic response performance of DC bus voltage is improved.

Study of the Dynamic Characteristics of Piston Chamber Pressure and its Optimizing

2014 ◽  
Vol 602-605 ◽  
pp. 277-282
Author(s):  
Bin Qu Yan ◽  
Shu Mei Chen ◽  
Chuan Ming Chen
Keyword(s):  
Dynamic Response ◽  
Operating Conditions ◽  
Piston Pump ◽  
Cylinder Block ◽  
Chamber Pressure ◽  
Excessive Pressure ◽  
New Type ◽  
The Stability ◽  
The Impact ◽  
Piston Chamber

In order to develop a new type of high-performance axial piston pump, the impact of the dynamic response characteristics of piston chamber pressure to the stability of cylinder block were analyzed. This paper a new type of valve plate which combined two fixed throttling grooves with a triangular groove (called three-level gain) was put forward so as to reducing the excessive pressure adjustment of the dynamic response of piston chamber pressure and improving the stability of cylinder block. The simulation results indicate that not only the cavitation is reduced, but also the stability of the dynamic response of piston chamber pressure is remained at various swash plate angle which makes it applicable to variable piston pump. The results also indicate that the flow pulsation of variable displacement pump is significantly decreased in different operating conditions.

Lateral Stability of Freight Cars With Axles Having Different Wheel Profiles and Asymmetric Loading

1979 ◽  
Vol 101 (1) ◽  
pp. 1-16 ◽  
Author(s):  
J. M. Tuten ◽  
E. H. Law ◽  
N. K. Cooperrider
Keyword(s):  
Dynamic Response ◽  
Strong Influence ◽  
Lateral Stability ◽  
Loading Conditions ◽  
Stability Behavior ◽  
Rail Freight ◽  
Rail Vehicle ◽  
Asymmetric Loading ◽  
Left And Right ◽  
The Stability

The majority of studies of rail vehicle lateral dynamic response have utilized models wherein it is assumed that the loading and geometry of the vehicles are symmetrical left and right and fore and aft. It has been observed that with use North American rail freight vehicles develop transverse wheel profiles that may be different for wheels on a given axle and that may also differ from axle to axle on a given vehicle. As the transverse wheel profiles exert a strong influence on lateral dynamic response by affecting the effective conicity and gravitational stiffness of the wheelset, models capable of having different wheel profiles on the same axle as well as on different axles were developed to investigate the stability behavior. Additionally, these models were formulated so that the effects on stability of asymmetric fore and aft loading conditions, as manifested through gravitational stiffness effects and creep coefficients, could be examined. Results of studies using these models are presented that display characteristics markedly different from those of completely symmetric models. A particularly interesting result is that, in most cases, the lateral stability of vehicles with different wheel profiles on the various axles is strongly sensitive to the direction of motion with results for each direction of motion which may differ radically from symmetric cases.

scholarly journals Investigation on Damping Characteristics of Hydrostatic Bearing Film by Using Scale Method

2021 ◽  
Author(s):  
Sheng-Yen Hu ◽  
Wen-Chou Chen ◽  
Chien-Hsun Wang ◽  
Hsin-Ming Fu ◽  
Yuan Kang
Keyword(s):  
Damping Ratio ◽  
Resonant Peak ◽  
Test Results ◽  
Scaling Method ◽  
Single Degree Of Freedom ◽  
Hydrostatic Bearing ◽  
Damping Characteristics ◽  
Mass Spring ◽  
The Impact

Abstract The resonant peaks can be suppressed by damping, those effects is dependent on damping ratio of system. In this paper, we propose a scaling method to evaluate the damping ratio of hydrostatic bearings for the data from model test. This method fits specifically for the overdamping of all hydrostatic bearing. This is direct and the easiest method to obtain the damping characteristics of oil film for the lowest band before the first resonant peak. The frequency responses of acceleration per force for a single-degree-of-freedom mass-spring-damper model is used to generate the evaluation scales for the damping ratios of the modal test results of worktable mounting on hydrostatic bearing. The case study for experimental results of the impact response are evaluated for damping ratio of the hydrostatic film by these method. Furthermore, using this scaling method, the influences of three types of compensations on the damping ratio of a hydrostatic bearing are compared. The results reveal that the constant flow has the largest damping ratio, and the capillary restrictor has the smallest one.

Experimental Investigation of Vibration Damping Behavior of Magneto-Mechanical Coated AISI321 Stainless-Steel

2019 ◽  
Author(s):  
Hafiz Muhammad Ashraf ◽  
Farhan Ali
Keyword(s):  
Stainless Steel ◽  
Dynamic Response ◽  
High Speed ◽  
High Cycle Fatigue ◽  
Damping Ratio ◽  
Base Material ◽  
Rotating Machinery ◽  
Cycle Fatigue ◽  
Damping Characteristics ◽  
Aisi 321

Abstract High speed rotating machineries usually operate under severe conditions and enormous loadings and thus, are susceptible to several problems. One such problem that has caught the attention in recent decades is known as High Cycle Fatigue. More than 60 percent of rotating machinery failures has been attributed to this High cycle Fatigue. Along with High Cycle Fatigue, Vibration, an inherent phenomenon in machineries, also share its part in failure of rotating machineries. Rotating machinery components suffer from high amplitude vibrations when they pass through resonance. Stresses are developed as a result of these vibrations and fatigue in mechanical structures, providing a conducive environment for the development of cracks at Surface. When these surface cracks reach critical size, crack nucleation starts, which ultimately leads to catastrophic failures. So, in order to avoid the disastrous consequences, damping is needed. Damping keeps material’s integrity in case of impact forces, stresses due to thermal shocks in turbo machinery and earth quakes in huge structures. Thin layer of magneto elastic coating can be applied on substrate surface that acts as first line of defense. Large number of coating Processes are available around the globe. The optimized combination of coating material, substrate material and coating technique according to specific application is necessary. These coatings have the capability to combat the phenomenon of oxidation, wear and fatigue acting as a barrier between substrate and hostile environments. Further, they enhance the damping characteristics, and thus allows the high-speed rotating machinery to reach its operational speed without any failure at resonance. In this way, they not only enhance the performance of components in aggressive environments, but also improve the life cycle, saving assets of millions of dollars’ worth. This research is an endeavor to experimentally investigate effect of magneto mechanical coating on damping of AISI 321 Stainless steel. AISI 321 was selected as base material because of its wide applications in engine components of gas turbines, heat exchangers and in different chemical industries. Two types of Air plasma sprayed magneto-mechanical powder (NiAl & CoNiCrAlY) were coated on base material and thickness was maintained up to 250μm in both the cases. Experiments were designed and performed on cantilever beam specimens for dynamic response measurement. Dynamic response of the system was measured to investigate the modal parameters of natural frequencies, damping ratio and time of vibration decay. For damping ratio, vibration analyzer mode was adjusted in time domain and beam was excited by using a hammer. Vibration analyzer showed the vibration decay as a function of time. Logarithmic decrement method was used to calculate the damping ratio in both cases. Dynamic response of all the three cases (NiAl coating, CoNiCrAlY and uncoated AISI321) were compared. Results were very reassuring and showed a significant improvement in damping characteristics.

Experimental Investigation of Vibration Damping Behavior of Magneto-Mechanical Coated AISI321 Stainless-Steel

2020 ◽  
Author(s):  
Hafiz Muhammad Ashraf ◽  
Farhan Ali ◽  
Muhammad Imran Sadiq
Keyword(s):  
Stainless Steel ◽  
Dynamic Response ◽  
High Cycle Fatigue ◽  
Damping Ratio ◽  
Base Material ◽  
Rotating Machinery ◽  
Cycle Fatigue ◽  
Damping Characteristics ◽  
Aisi 321 ◽  
Rotating Machineries

Abstract High speed rotating machineries usually operate under severe conditions and enormous loadings and thus, are susceptible to several problems. One such problem that has caught the attention in recent decades is known as High Cycle Fatigue. More than 60 percent of rotating machinery failures has been attributed to this High cycle Fatigue. Along with High Cycle Fatigue, Vibration, an inherent phenomenon in machineries, also share its part in failure of rotating machineries. Rotating machinery components suffer from high amplitude vibrations when they pass through resonance. Stresses are developed as a result of these vibrations and fatigue in mechanical structures, providing a conducive environment for the development of cracks at Surface. When these surface cracks reach critical size, crack nucleation starts, which ultimately leads to catastrophic failures. So, in order to avoid the disastrous consequences, damping is needed. Damping keeps material’s integrity in case of impact forces, stresses due to thermal shocks in turbo machinery and earth quakes in huge structures. Thin layer of magneto elastic coating can be applied on substrate surface that acts as first line of defense. Large number of coating Processes are available around the globe. The optimized combination of coating material, substrate material and coating technique according to specific application is necessary. These coatings have the capability to combat the phenomenon of oxidation, wear and fatigue acting as a barrier between substrate and hostile environments. Further, they enhance the damping characteristics, and thus allows the highspeed rotating machinery to reach its operational speed without any failure at resonance. In this way, they not only enhance the performance of components in aggressive environments, but also improve the life cycle, saving assets of millions of dollars’ worth. This research is an endeavor to experimentally investigate effect of magneto mechanical coating on damping of AISI 321 Stainless steel. AISI 321 was selected as base material because of its wide applications in engine components of gas turbines, heat exchangers and in different chemical industries. Two types of Air plasma sprayed magneto-mechanical powder (NiAl & CoNiCrAlY) were coated on base material and thickness was maintained up to 250μm in both the cases. Experiments were designed and performed on cantilever beam specimens for dynamic response measurement. Dynamic response of the system was measured to investigate the modal parameters of natural frequencies, damping ratio and time of vibration decay. For damping ratio, vibration analyzer mode was adjusted in time domain and beam was excited by using a hammer. Vibration analyzer showed the vibration decay as a function of time. Logarithmic decrement method was used to calculate the damping ratio in both cases. Dynamic response of all the three cases (NiAl coating, CoNiCrAlY and uncoated AISI321) were compared. Results were very reassuring and showed a significant improvement in damping characteristics.

Investigation of Granular Damping in Transient Vibrations Using Hilbert Transform Based Technique

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
X. Fang ◽  
H. Luo ◽  
J. Tang
Keyword(s):  
Hilbert Transform ◽  
Damping Ratio ◽  
Temporal Frequency ◽  
Nonlinear Damping ◽  
Vibration Level ◽  
Damping Characteristics ◽  
The Difference ◽  
The Hilbert Transform ◽  
Granular Damping ◽  
The Impact

Granular damping results from a combination of energy dissipation mechanisms including the impact and the friction between the vibrating structure and granules and among the granules. Although simple in concept, granular damping is very complicated and its performance depends on a number of factors, such as vibration level, granular material properties, packing ratio, etc. In this study, free vibration experiments are conducted on a cantilevered beam incorporated with granular damping. A signal analysis approach based on the Hilbert transform (HT) is then employed to identify the nonlinear damping characteristics from the acquired responses, such as the dependency of the natural frequency and damping ratio on the vibration level. This HT based analysis can produce an effective temporal-frequency amplitude∕energy analysis, which provides us with physical insights of the nonlinear transient response. A direct comparison between the granular damping and the impact damping (with single impactor to dissipate vibratory energy) is performed to highlight the difference between these two and the advantages of granular damping. Finally, the validity of the proposed approach is also examined by the successful prediction of vibration response using the extracted granular damping characteristics.

Dynamic Response of a Heterotypic Concrete Filled Steel Tube Arch Bridge Subjected to Moving Vehicles

2011 ◽  
Vol 255-260 ◽  
pp. 1696-1700
Author(s):  
Yan Li ◽  
Xin Yi Huang
Keyword(s):  
Surface Roughness ◽  
Dynamic Response ◽  
Impact Factor ◽  
Damping Ratio ◽  
Steel Tube ◽  
Impact Factors ◽  
Arch Bridge ◽  
Concrete Filled Steel Tube ◽  
Moving Vehicles ◽  
The Impact

As a new type structure, the dynamic behavior of the irregular concrete filled steel tube arch bridge under moving vehicles was rarely studied. In this paper, taking the bridge crossing Yitong river in Changchun of China as an example, the dynamic response of the bridge is investigated by the self-compiling vehicle-bridge coupled vibration analysis program. The surface roughness and vehicle speed are considered in the analysis. The results show that impact factors of the bridge increase as surface roughness deteriorated; the impact factor varies obviously for the different component; the tension impact factor of the short suspender is larger than that of long ones; damping ratio of structure has little effect on the impact factors. The research conclusions can be referred in the design and assessment for the similar bridges.

Dynamic Response of a Beam With Absorber Exposed to a Running Force: Fractional Calculus Approach

2012 ◽  
Author(s):  
Ibrahim Abu-Alshaikh ◽  
Anas N. Al-Rabadi ◽  
Hashem S. Alkhaldi
Keyword(s):  
Fractional Calculus ◽  
Dynamic Response ◽  
Fractional Derivative ◽  
Initial Conditions ◽  
Damping Ratio ◽  
Experimental Models ◽  
Damping Characteristics ◽  
Damping Behavior ◽  
The Laplace Transform ◽  
Vibration Parameters

This paper analyzes the transverse vibration of Bernoulli-Euler homogeneous isotropic simply-supported beam. The beam is assumed to be fractionally-damped and attached to a single-degree-of-freedom (SDOF) absorber with fractionally-damping behavior at the mid-span of the beam. The beam is also exposed to a running force with constant velocity. The fractional calculus is introduced to model the damping characteristics of both the beam and absorber. The Laplace transform accompanied by the used decomposition method is applied to solve the handled problem with homogenous initial conditions. Subsequently, curves are depicted to measure the dynamic response of the utilized beam under different set of vibration parameters and different values of fractional derivative orders for both of the beam and absorber. The results obtained show that the dynamic response decreases as both the damping-ratio of the absorber and beam increase. The results reveal that there are critical values of fractional derivative orders which are different from unity. At these optimal values, the beam behaves with less dynamic response than that obtained for the full-order derivatives model of unity order. Therefore, the fractional derivative approach provides better damping models for fractionally-damped structures and materials which may allow researchers to choose suitable mathematical models that precisely fit the corresponding experimental models for many engineering applications.

scholarly journals Identification of process damping for chatter prediction in milling

2018 ◽  
Vol 175 ◽  
pp. 02002
Author(s):  
Charles M. Zheng ◽  
Chou-Fu Liang ◽  
Hai-Yi Cai ◽  
Shui-Shen Zhang
Keyword(s):  
Damping Ratio ◽  
Depth Of Cut ◽  
Structural Damping ◽  
Stability Lobe Diagram ◽  
Easy Method ◽  
Process Damping ◽  
Stability Lobe ◽  
Mathematical Expressions ◽  
The Stability ◽  
The Impact

Traditionally, forecasting stability lobe diagram in milling is limited by complex damping identification procedures, so only structural damping from the impact experiment is used for predicting stability lobe diagram in most milling cases. In this study, by using the mathematical expressions among damping ratio, “critical limiting depth of cut” and “worst spindle speed”, it is shown that the predicted “critical limiting depth of cut” based on the structural damping divided by the measured “critical limiting depth of cut” can be approximately equal to the structural damping divided by the total damping. Based on this relationship, it is easy to estimate the total damping or process damping from the experiment within the selected spindle speeds. In practice, this paper presents an easy method for predicting stability lobe diagram using the total damping. At the same time, experiments have confirmed that using the prediction model of total damping can more accurately predict the stability lobe diagram.

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