Determination of impact events on a plate-like composite structure

2016 ◽  
Vol 120 (1228) ◽  
pp. 984-1004 ◽  
Author(s):  
L. Xu ◽  
Y. Wang ◽  
Y. Cai ◽  
Z. Wu ◽  
W. Peng
Keyword(s):  
Composite Structures ◽  
Transfer Functions ◽  
Flat Glass ◽  
Time History ◽  
Identification Algorithm ◽  
Impact Location ◽  
Force Time ◽  
The Impact ◽  
The Relationship ◽  
Impact Events

ABSTRACTComposite materials have been increasingly used in aircraft structures. However, these composite structures are susceptible to damage from external low-velocity impacts. In this paper, an impact identification algorithm is proposed to estimate the impact location and force time history simultaneously. A localisation method based on basis vectors is proposed, and the impact force time history is reconstructed by simplified transfer functions. The basis vector stands for the relationship between the impact location and the sensor signals, and the transfer function shows the relationship of the sensor signal and the force time history. An experiment is conducted on a flat glass fibre-epoxy matrix composite plate to verify the developed algorithm using only four sensors. The soft impactor and hard impactor are two typical impactors for impact events; therefore, the impact experiment is performed by the rubber and the steel impactors, respectively. The experimental results indicate that the proposed algorithm is feasible for the identification of impact events on plate-like composite structures.

scholarly journals Development of Time-Reversal Method for Impact Source Identification on Plate Structures

2013 ◽  
Vol 20 (3) ◽  
pp. 561-573 ◽  
Author(s):  
Chunlin Chen ◽  
Yulong Li ◽  
Fuh-Gwo Yuan
Keyword(s):  
Impact Loading ◽  
Time Reversal ◽  
Source Identification ◽  
Transfer Functions ◽  
Plate Thickness ◽  
Time History ◽  
Numerical Verification ◽  
Impact Location ◽  
Location Detection ◽  
The Impact

This paper presents a detailed study on the impact source identification of a plate structure using time-reversal (T-R) method. Prior to impact monitoring, the plate is calibrated (or characterized) by transfer functions at discrete locations on the plate surface. Both impact location and impact loading time-history are identified using T-R technique and associated signal processing algorithms. Numerical verification for finite-size isotropic plates under low velocity impacts is performed to demonstrate the versatility of T-R method for impact source identification. The tradeoff between accuracy of the impact location detection and calibration spacing is studied in detail. In particular, the effect of plate thickness on calibration spacing has been examined. A number of parameters selected for determining the impact location, approximated transfer functions and steps taken for reconstructing the impact loading time-history are also examined. Two types of noise with various intensities contaminated in strain response and/or transfer functions are investigated for demonstrating the stability and reliability of the T-R method. The results show that T-R method is robust against noise in impact location detection and force reconstruction in circumventing the inherent ill-conditioned inverse problem. Only transfer functions are needed to be calibrated and four sensors are requested in T-R method for impact identification.

scholarly journals Effect of Multi-Impact on QIQH Carbon/Epoxy Composite Laminate

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 511
Author(s):  
Adadé Seyth Ezéckiel Amouzou ◽  
Olivier Sicot ◽  
Ameur Chettah ◽  
Shahram Aivazzadeh
Keyword(s):  
Composite Structures ◽  
Epoxy Composite ◽  
Impact Damage ◽  
Ultrasonic Control ◽  
Impact Tests ◽  
Post Impact ◽  
Testing Techniques ◽  
Force Time ◽  
The Relationship ◽  
Force Displacement

This work is motivated by increasingly used of composite structures under severe loading conditions. During their use, these materials are often subjected to impact as for example, in the aeronautical field the fall of hailstone on structure composites. In fact, the low energy traditional impact tests don’t allow to see the evolution of the damage and don’t permit also to compare the best tolerance to impact between different stratifications. The multi-impact tests made it possible to find a solution to this problem. In this work, multi-impact tests are performed on three carbon/epoxy stratifications. The final goal is to predict the durability of the composite structures during impact loading for their design. This study brings to light the response of multi-impact tests through force-time and force-displacement curves obtained experimentally. On the other hand, a parameter D has introduced following the experimental results. This made it possible to rank the three stratifications from their tolerance to multi-impact tests. To evaluate the post impact damage, ultrasonic testing techniques are used. The results allow to find the relationship between the damaged surface obtained by the ultrasonic control and the parameter D and to rank the three laminates configurations.

An Enhanced Time-Reversal Method for Impact Damage Monitoring on Plate-Like Structures

2012 ◽  
Vol 525-526 ◽  
pp. 365-368
Author(s):  
Chun Lin Chen ◽  
Yu Long Li ◽  
Fuh Gwo Yuan
Keyword(s):  
Time Reversal ◽  
Composite Structures ◽  
Impact Damage ◽  
High Energy ◽  
Low Velocity ◽  
Energy Impact ◽  
Location Detection ◽  
Focusing Property ◽  
The Impact ◽  
Impact Events

Based on the self-focusing property of time-reversal (T-R) concept, a time focusing parameter was suggested to improve the impact source identification method developed in authors previous work. This paper presents a further study on monitoring relatively high energy impact events which caused induced damage on structures. Numerical verifications for a finite isotropic plate and a composite plate under low velocity impacts are performed to demonstrate the versatility of T-R method for impact location detection with induced plastic deformation and delamination damage on metallic and composite structures respectively. The focusing property of T-R concept was adequately utilized to detect impact/damage location. The results show that impact events with various features can be localized using T-R method by introducing the time focusing parameter. It is suited to monitor serious impact events on plate like structures in practice in future.

Development of Imaging Technique for Evaluating the RC Plate Containing Epoxy-Repaired Delamination

2006 ◽  
Vol 321-323 ◽  
pp. 348-351 ◽  
Author(s):  
Chia Chi Cheng ◽  
Kuang Chih Pei ◽  
Jiunn Hong Wu
Keyword(s):  
Transfer Functions ◽  
Imaging Technique ◽  
Crack Depth ◽  
Spectral Image ◽  
Impact Echo ◽  
Amplitude Spectra ◽  
Before And After ◽  
Force Time ◽  
The Impact ◽  
Crack Widths

The paper introduces a newly developed imaging technique for evaluating the integrity of concrete structures. The image of normalized amplitude spectra is obtained from B-scan of impact-echo tests. The normalizing process was carried out by obtaining the simulated transfer functions, in which the displacement of R-wave waveform of the impact-echo response multiplying a correcting factor is used as the simulated force-time function. Two specimens, one reinforced and the other unreinforced concrete plates, containing naturally delaminated cracks with crack widths 1 mm, 3 mm and 5 mm were constructed and repaired by injected epoxy into the delaminated cracks. The NDT method was performed on the specimens before and after the repairing work for comparison. The spectral image shows consistent high intensity at the crack-depth-frequency for specimens at crack stages and less in intensity for the ones at repaired stage.

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.

EFFECT OF THE FLUID ON THE IMPACT FORCE OF THE WET MISSILE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Duc-Kien Thai ◽  
Seung-Eock Kim
Keyword(s):  
Impact Force ◽  
Force Plate ◽  
Time History ◽  
Research Centre ◽  
Element Analysis ◽  
Time Histories ◽  
Target Wall ◽  
Force Time ◽  
Missile Test ◽  
The Impact

In this paper, the force-time histories of soft missiles, with and without filled water, impacting the target wall were investigated using finite element analysis. The force plate tests, with a dry missile (test FP8) and a wet missile (test FP16) carried out by Technical Research Centre of Finland (VTT), were used. The numerical analysis results were verified by comparing with those of experiments. A parametric analysis with different missile velocities was also performed to investigate the force-time history and impulse of the missile impact on target plate. Based on a comparison with the Riera approach, the coefficients were proposed to modify the Riera function. The analysis results show that, the Riera function accurately predicted the impact force time history in the case of the dry missile. However, in the case of the wet missile, the coefficients α from 1.24 to 1.45 are recommended to be added to the second term of the Riera function in the case in which the impact velocity is in the range of 70 m/s to 200 m/s.

scholarly journals An Evidence Basis for Future Equestrian Helmet Lateral Crush Certification Tests

2020 ◽  
Vol 10 (7) ◽  
pp. 2623 ◽  
Author(s):  
Thomas A. Connor ◽  
J. Michio Clark ◽  
Pieter Brama ◽  
Matt Stewart ◽  
Aisling Ní Annaidh ◽  
...  
Keyword(s):  
Time History ◽  
Test Method ◽  
Published Data ◽  
Mean Values ◽  
Safety Outcome ◽  
Certification Tests ◽  
Impact Location ◽  
Peak Loads ◽  
Equestrian Sports ◽  
Force Time

The aim of this study is to determine what loads are likely to be applied to the head in the event of a horse falling onto it and to determine by how much a typical equestrian helmet reduces these loads. An instrumented headform was designed and built to measure applied dynamic loads from a falling horse. Two differently weighted equine cadavers were then dropped repeatedly from a height of 1 m (theoretical impact velocity of 4.43 m/s) onto both the un-helmeted and helmeted instrumented headforms to collect primary force–time history data. The highest mean peak loads applied to the headform by the lighter horse were measured at the bony sacral impact location (15.57 kN ± 1.11 SD). The lowest mean peak loads were measured at the relatively fleshier right hind quarter (7.91 kN ± 1.84 SD). For the heavier horse, highest mean peak loads applied to the headform were measured at the same bony sacral impact location (16.02 kN ± 0.83 SD), whilst lowest mean peak loads were measured at the more compliant left hind quarter (10.47 kN ± 1.08 SD). When compared with the un-helmeted mean values, a reduction of 29.7% was recorded for the sacral impact location and a reduction of 43.3% for the lumbosacral junction location for helmeted tests. Notably, all measured loads were within or exceeded the range of published data for the fracture of the adult lateral skull bone. Current helmet certification tests are not biofidelic and inadequately represent the loading conditions of real-world “lateral crush” accidents sustained in equestrian sports. This work presents the first ever evidence basis upon which any future changes to a certification standards test method might be established, thereby ensuring that such a test would be both useful, biofidelic, and could ensure the desired safety outcome.

Testing and Error Analysis of some Structure’s Impact Load

2010 ◽  
Vol 139-141 ◽  
pp. 2473-2477
Author(s):  
Ji Ping Wu ◽  
You Xing Cai
Keyword(s):  
Impact Load ◽  
Time History ◽  
Load Testing ◽  
Object Based ◽  
Impact Theory ◽  
Finite Element Technology ◽  
Testing Accuracy ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

The shock response of single freedom system was studied based on impact theory. The shear blade of some merchant shearing machine was selected as the object. The static calibration and impact load testing was carried on the object. Based on the impact theory and finite element technology, the feasibility of the testing scheme and the influence of the shock wave shape on the testing accuracy were discussed. The results show that for the shear blade, when the impact load time history is 50ms and the natural frequency is 2848Hz, there only 0.42% difference between the maximum dynamic response and the static calibrated response. So it is practicable to use the static calibrated results to decide the relationship of the impact load and strain.

scholarly journals Dynamic effects induced by the impact of debris flows on protection barriers

2018 ◽  
Vol 10 (1) ◽  
pp. 116-131 ◽  
Author(s):  
Maddalena Marchelli ◽  
Valerio De Biagi
Keyword(s):  
Impact Force ◽  
Time History ◽  
Element Model ◽  
Interaction Force ◽  
Accurate Analysis ◽  
Vibration Period ◽  
Time Histories ◽  
Mode Vibration ◽  
Force Time ◽  
The Impact

Debris flow is a transient phenomenon that causes large disasters. Retaining systems, whose design is still nowadays a crucial issue, can mitigate this risk. Multiple surges can arise during this phenomenon; thus, an accurate analysis might consider the impact force time histories rather than only its maxima. The aim of this work is to analyze the effects of the interaction between the debris and the barrier during one surging phenomenon. A discrete element model models the granular motion and the interaction between the debris and a rigid open barrier set at the end of the channel. The estimated interaction force time history is then used as input impact force for the dynamic structural analyses of the piles. A total of 12 different structural sections are adopted and the internal forces at the base are critically compared. It results that the first mode vibration period is the parameter that largely affects the behavior of the piles.

scholarly journals Investigation of the Impact of Seed Record Selection on Structural Response

2010 ◽  
Author(s):  
Thomas W. Houston ◽  
Greg E. Mertz ◽  
Michael C. Costantino ◽  
Carl J. Costantino
Keyword(s):  
Transfer Functions ◽  
Structural Response ◽  
Time History ◽  
Response Spectra ◽  
Recent Experience ◽  
Target Response ◽  
Target Spectrum ◽  
Time Histories ◽  
Record Selection ◽  
The Impact

Time history records are typically used to define the seismic demand for critical structures for which soil structure interaction (SSI) analyses are often required. Criteria for the development of time histories is provided in ASCE 43-05. The time histories are based on a close fit of 5% damped target response spectra. Recent experience has demonstrated that for cases where the transfer functions associated with the structural response are narrow, the ASCE 43-05 criteria can under-predict peak spectral responses in the structure by as much as 70% in some frequency ranges. One potential solution for this issue is to reinstate requirements for matching target response spectra for multiple damping levels to ASCE 43-05 criteria. However, recent probabilistic seismic hazard analyses (PSHA) do not generally contain spectra for multiple damping levels. This paper proposes an approach to generate target spectra at multiple damping levels, given the 5% damped target spectrum provided by the PSHA, utilizing catalogs of recorded earthquakes. The process of fitting time histories to multiple damped spectra is effective in correcting defficiencies observed in the computed structural response when time histories meeting the ASCE 43-05 fitting criteria are used.

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