scholarly journals Importance of Selecting a Suitable Analysis Frequency Range in Impact Force Identification for Automobile Test Rig

2014 ◽  
Vol 663 ◽  
pp. 88-92
Author(s):  
Khoo Shin Yee ◽  
Ong Zhi Chao ◽  
Kong Keen Kuan ◽  
Zubaidah Ismail ◽  
Chong Wen Tong ◽  
...  
Keyword(s):  
Impact Force ◽  
Excitation Frequency ◽  
Time History ◽  
Transformation Method ◽  
Dynamic Force ◽  
Frequency Range ◽  
Test Rig ◽  
Force Identification ◽  
History Of ◽  
The Impact

In this study, the effectiveness of selecting a suitable analysis frequency range in impact force identification is highlighted. A methodology that utilizesOperating Deflection Shape (ODS) analysis, Modal Analysis (MA) and Modal Transformation Method (MTM) to evaluate the dynamic force in three cases of analysis frequency ranges was presented. These three cases are the over-estimated, even-estimated, and under-estimated cases, which consist of higher, similar andlower analysis frequency range respectively, compared to the actual excitation frequency range. The performance of this approach was demonstrated via experiment. A Perspex plate with four ground supports was used as the automobile test rig. By measuring the acceleration response and Frequency Response Function (FRF) of the test rig, the time history of unknown force was recovered by the proposed method where the impact location was known in advance. It showed that the force identification result for even-estimated case falls within acceptable range while the force identification result for over-estimated and under-estimated cases isnot acceptable

scholarly journals Impact Force Identification by Using Modal Transformation Method for Automobile Test Rig

2013 ◽  
Vol 471 ◽  
pp. 102-106 ◽  
Author(s):  
Abdul Ghaffar Abdul Rahman ◽  
Khoo Shin Yee ◽  
Zubaidah Ismail ◽  
Chong Wen Tong ◽  
Siamak Noroozi
Keyword(s):  
Impact Force ◽  
Force Measurement ◽  
Transformation Method ◽  
Impact Excitation ◽  
Dynamic Force ◽  
Test Rig ◽  
Force Identification ◽  
Input Force ◽  
Material Fatigue

In the automobile industry, impact force is the main cause for material fatigue in lightweight vehicles. Bump-excited impact force is the most common case, which causes damage to vehicles and reduces the quality of the ride. Force identification is important to reflect the structure's health so that action such as structure modification can be taken before material fatigue. However, direct measurement by using force transducer is not practical due to difficulty in force sensor configuration. A methodology utilizing Operating Deflection Shape (ODS) analysis, Frequency Response Function (FRF) measurement and Modal Transformation Method (MTM) to evaluate the dynamic force is proposed here. This method is called indirect force measurement by using inverse technique. The performance of this approach was demonstrated via experiment. From the measured responses and measured dynamic characteristics of an automobile test rig, a real time mathematical manipulation can generate the systems input force. The force location is known in priori for impact excitation and therefore the inverse problem is well-posed. This method was tested using different force location with unique input force. It shows that high quality of curve fitting to extract the modal parameters such as damped natural frequency, modal damping and residue mode shape is essential to obtain a high accuracy force determination result.

scholarly journals Transient Response of an Impacted Beam and Indirect Impact Force Identification Using Strain Measurements

1994 ◽  
Vol 1 (3) ◽  
pp. 267-278 ◽  
Author(s):  
Hyungsoon Park ◽  
Youn-sik Park
Keyword(s):  
Impulse Response ◽  
Impact Force ◽  
Impulse Response Function ◽  
Time History ◽  
Impulse Response Functions ◽  
Transverse Impact ◽  
History Of ◽  
Convolution Approach ◽  
The Time Domain ◽  
The Impact

The impulse response functions (force-strain relations) for Euler–Bernoulli and Timoshenko beams are considered. The response of a beam to a transverse impact force, including reflection at the boundary, is obtained with the convolution approach using the impulse response function obtained by a Laplace transform and a numerical scheme. Using this relation, the impact force history is determined in the time domain and results are compared with those of Hertz's contact law. In the case of an arbitrary impact, the location of the impact force and the time history of the impact force can be found. In order to verify the proposed algorithm, measurements were taken using an impact hammer and a drop test of a steel ball. These results are compared with simulated ones.

On the Experimental Dynamic Force Performance of a Squeeze Film Damper Supplied Through a Check Valve and Sealed With O-Rings

2021 ◽  
Author(s):  
Luis San Andrés ◽  
Bryan Rodríguez
Keyword(s):  
Dynamic Pressure ◽  
Excitation Frequency ◽  
Check Valve ◽  
Forced Response ◽  
Single Frequency ◽  
Squeeze Film ◽  
Dynamic Force ◽  
Viscous Damping ◽  
Test Rig ◽  
Force Coefficients

Abstract In rotor-bearing systems, squeeze film dampers (SFDs) assist to reduce vibration amplitudes while traversing a critical speed and also offer a means to suppress rotor instabilities. Along with an elastic support element, SFDs are effective means to isolate a rotor from its casing. O-rings (ORs), piston rings (PRs) and side plates as end seals reduce leakage and air ingestion while amplifying the viscous damping in configurations with limited physical space. ORs also add a centering stiffness and damping to a SFD. The paper presents experiments to quantify the dynamic forced response of an O-rings sealed ends SFD (OR-SFD) lubricated with ISO VG2 oil supplied at a low pressure (0.7 bar(g)). The damper is 127 mm in diameter (D), short in axial length L = 0.2D, and the film clearance c = 0.279 mm. The lubricant flows into the film land through a mechanical check valve and exits through a single port. Upstream of the check valve, a large plenum filled with oil serves to attenuate dynamic pressure disturbances. Multiple sets of single-frequency dynamic loads, 10 Hz to 120 Hz, produce circular centered orbits with amplitudes r = 0.1c, 0.15c and 0.2c. The experimental results identify the test rig structure, ORs and SFD force coefficients; namely stiffness (K), mass (M) and viscous damping (C). The ORs coefficients are frequency independent and show a sizeable direct stiffness, KOR ∼ 50% of the test rig structure stiffness, along with a quadrature stiffness, K0∼0.26 KOR, demonstrative of material damping. The lubricated system damping coefficient equals CL = (CSFD + COR); the ORs contributing 10% to the total. The experimental SFD damping and inertia coefficients are large in physical magnitude; CSFD slightly grows with orbit size whereas MSFD is relatively constant. The added mass (MSFD) is approximately four-fold the bearing cartridge mass; hence, the test rig natural frequency drops by ∼50% once lubricated. A computational physics model predicts force coefficients that are just 10% lower than those estimated from experiments. The amplitude of measured dynamic pressures upstream of the plenum increases with excitation frequency. Unsuspectedly, during dynamic load operation, the check valve did allow for lubricant backflow into the plenum. Post-tests verification demonstrates that, under static pressure conditions, the check valve does work since it allows fluid flow in just one direction.

A system for simulating the kinematics and measuring the impact force from riding whips used in Thoroughbred horseracing

2020 ◽  
pp. 175433712098062
Author(s):  
John W Bridge ◽  
Kaleb M Dempsey ◽  
Kayla M Danicki ◽  
Robin L Angotti ◽  
Alan K Kwiatkowski ◽  
...  
Keyword(s):  
Impact Force ◽  
Dynamic Force ◽  
Horse Racing ◽  
Testing Device ◽  
Shaft Length ◽  
Impact Forces ◽  
The Face ◽  
Flap Design ◽  
Arm Motion ◽  
The Impact

Thirty horse racing whips of four different designs were tested to measure dynamic impact force and compared using a specially designed mechanical testing device to simulate the whipping action of a jockey during racing. The whips tested included designs used in Thoroughbred horse racing in North America, which meet the design criteria established by the Association of Racing Commissioners International (ARCI) model rules, as well as the most common whip used in British horse racing. The objective of the device was to allow comparisons to be made between peak impact loads resulting from different whip designs. A high peak dynamic force on a horse’s shoulder or hind quarter may result in injuries, such as welts. The testing device contains a planar three-bar, open mechanical linkage loaded by torsion springs to model the arm motion of a jockey. The whip strikes a flat plate covered by an elastomeric pad. The energy input is replicated during the simulated impact. A single axis dynamic load cell under the loading plate and three single-turn precision potentiometers located at each joint of the three-arm mechanical system measure impact forces and relative angular positions, respectively. Force measurements are compared from the face of each whip and the edge or seam where applicable. In addition to the flap design, other physical differences between whip designs included mass, shaft length, shaft stiffness, flap cushion thickness/compression factor, flap surface area, and flap seam area. Statistically significant impact force differences were found between flap face and flap seam impact orientations, with higher impact forces delivered by the flap face. Significant differences were also found in impact forces between the three whip styles with seams.

scholarly journals Study on the Impact Resistance of Metal Flexible Net to Rock fall

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Gaosheng Wang ◽  
Yunhou Sun ◽  
Ao Zhang ◽  
Lei Zheng ◽  
Yuzheng Lv ◽  
...  
Keyword(s):  
Finite Element ◽  
Impact Force ◽  
Impact Resistance ◽  
Time History ◽  
Rock Fall ◽  
Fe Model ◽  
Element Analysis ◽  
Inclination Angles ◽  
Fall Protection ◽  
The Impact

Based on experiments and finite element analysis, the impact resistance of metal flexible net was studied, which can provide reference for the application of metal flexible net in rock fall protection. The oblique (30 degrees) impact experiment of metal flexible net was carried out, the corresponding finite element (FE) to the experiment was established, and the FE model was verified by simulation results to the experimental tests from three aspects: the deformation characteristics of metal flexible net, the time history curves of impact force on supporting ropes, and the maximum instantaneous impact force on supporting ropes. The FE models of metal flexible nets with inclination angles of 0, 15, 30, 45, 60, and 75 degrees were established, and the impact resistance of metal flexible nets with different inclination angles was analyzed. The research shows that the metal flexible net with proper inclination can bounce the impact rock fall out of the safe area and prevent rock fall falling on the metal flexible net, thus realizing the self-cleaning function. When the inclination angle of the metal flexible net is 15, 30, and 45 degrees, respectively, the bounce effect after impact is better, the remaining height is improved, the protection width is improved obviously, and the impact force is reduced. Herein, the impact force of rock fall decreases most obviously at 45 degrees inclination, and the protective performance is relatively good.

Finite Element Analysis of a Single-Layer Reticulated Dome under Impact Loading

2010 ◽  
Vol 163-167 ◽  
pp. 327-331 ◽  
Author(s):  
Liang Zheng ◽  
Zhi Hua Chen
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Impact Force ◽  
Impact Load ◽  
Residual Deformation ◽  
Time History ◽  
Single Layer ◽  
Element Analysis ◽  
Deformation Stage ◽  
The Impact

Finite element model of both the single-layer Schwedler reticulated dome with the span of 50m and a Cuboid impactor were developed, incorporating ANSYS/LS-DYNA. PLASTIC_KINEMATIC (MAT_003) material model which takes stain rate into account was used to simulate steel under impact load. The automatic point to surface contact (NODES TO SURFACE) was applied between the dome and impact block. Three stages of time history curve of the impact force on the apex of the single-layer Scheduler reticulated dome including the impact stage, stable stalemate stage, the decaying stage were generalized according to its dynamic response. It must be pointed out that the peak of the impact force of the single-layer reticulated dome increase with the increase of the weight and the velocity of the impact block, but the change of the velocity of the impact block is more sensitive than the change of weight of the impact block for the effect of the peak of the impact force, and a platform value of the impact force of the single-layer reticulated dome change near a certain value, and the duration time of the impact gradually increase. Then four stages of time history curve of the impact displacement were proposed according to the dynamic response of impact on the apex of the single-layer reticulated dome based on numerical analysis. Four stages include in elastic deformation stage, plastic deformation stage, elastic rebound stage, free vibration stage in the position of the residual deformation.

Numerical Simulation and Experimental Study on Fluid-Filled Hemispherical Shell under Impact

2013 ◽  
Vol 364 ◽  
pp. 172-176
Author(s):  
Hui Wei Yang ◽  
Bin Qin ◽  
Zhi Jun Han ◽  
Guo Yun Lu
Keyword(s):  
Numerical Simulation ◽  
Dynamic Response ◽  
Impact Load ◽  
Elastic Recovery ◽  
Plastic Hinge ◽  
Time History ◽  
Hemispherical Shell ◽  
History Of ◽  
Local Impact ◽  
The Impact

The dynamic response of fluid-filled hemispherical shell in mass impact is studied by experiment using DHR9401. Combining the time history of impact force with experimental observation of the deformation process, it can be seen that the dynamic response can be divided into four stages: the flattening around the impact point, the forming and expanding outward of shell plastic hinge, the plastic edge region flatten by the punch, and elastic recovery. The experimental results show that: Because the shell filled with liquid, the local impact load that the shell suffered is translated into area load and loads on the inner shell uniformly, so that it has a high carrying capacity. Numerical simulation is used to study the time history of energy absorption of different shell structures. The result shows that the crashworthiness of sandwich fluid-filled shell is improved greatly. Under the certain impact energy, deformation of its inner shell is very small, which can provide effective security space.

ESTIMATION OF IMPACT LOAD IN THICK PLATE BY USING THEORETICAL GREEN FUNCTION AND EXPERIMENTAL MEASUREMENT OF VIBRATION

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1377-1382
Author(s):  
H. W. Kim ◽  
S. K. Lee
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Thick Plate ◽  
Impact Load ◽  
Plate Theory ◽  
Time History ◽  
Force Transducer ◽  
Good Prediction ◽  
History Of ◽  
The Impact

The classic plate theory (CPT) as a theoretical solution to an impact load has been used in a thin plate. However, The CPT is not any more useful solution for the impact load in the industrial power plant, which is generally constructed by the thick plate. In this paper a novel and effective approach is developed to determine the time history of the impact load on a thick aluminum plate based on the analysis of the acoustic waveforms measured by a sensor array located on the thick plate surface in combination with the theoretical Green's function for the plate. The Green's functions are derived based on either the exact elastodynamic or theory the approximate shear deformation plate theory (SDPT). If the displacement is measured on the plate, then the time history of impact load can be calculated by deconvolving the measured displacement with the theoretical Green's function. The reconstructed time history for impact load is compared with the time history of the impact load measured by the force transducer. A good prediction is found. This technique presents a valuable method for identification of source and may be applied to in-service structures under impact to signals recorded from acoustic emission of propagating cracks.

IMPACT FORCE RESPONSE OF SHORT CONCRETE FILLED STEEL TUBULAR COLUMNS UNDER AXIAL LOAD

2008 ◽  
Vol 22 (09n11) ◽  
pp. 1361-1368 ◽  
Author(s):  
GOUPING REN ◽  
ZHU LI
Keyword(s):  
Impact Force ◽  
Time History ◽  
Material Model ◽  
Critical Energy ◽  
Steel Tube ◽  
Peak Force ◽  
Impact Speed ◽  
Tubular Columns ◽  
Unitary Model ◽  
The Impact

The impact test on short concrete filled steel tubular column was conducted through DHR-9401 dropped hammer tester. Based on analysis on recorded time-history curve of impact force, the relations of impact force with respect to confining effect coefficient and impact speed are obtained. So are done that of the impact duration. By use of ANSYS/LS-DYNA, values of impact peak force in relation with those of impact speed were computed in the case of unitary material model and composite material model respectively. The simulation results show that peak force-speed curve of unitary model has better description of test data than that of composite one. Critical energy is found to increase linearly with the steel ratio when steel tube and concrete remain unchanged.

Study on the Uplift Force of Plunge Pool Slab

2014 ◽  
Vol 580-583 ◽  
pp. 1897-1900
Author(s):  
Chun Tao Wang ◽  
Bang Hua Xie ◽  
Wen Hui Zeng
Keyword(s):  
Low Frequency ◽  
Time History ◽  
Uplift Force ◽  
Plunge Pool ◽  
Discharge Water ◽  
Amplitude Vibration ◽  
History Of ◽  
Force Time ◽  
The Impact ◽  
Test Result

The impact of the flood discharge water flow from a high dam is rather great on the slab of a plunge pool, and may cause damages to the plunge pool and consequently endangers the dam body safety. Therefore, a reverse arch slab model was established on the base of a study on and a simulation of the rational scale of gaps between the plates of the plunge pool slab. The model was an arch ring containing 7 slabs. The uplift force time history of each slab was measured, and the uplift force power spectrum and probability density were analyzed. The test result shows that the uplift energy mainly centers in 0-15Hz frequency bandwidth, and mostly within 1Hz. It belongs to a low frequency and big amplitude vibration.

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