scholarly journals Vibration levels of stacked parcel packages in laboratory test environment. Over-tested or under-tested?

2021 ◽  
Author(s):  
Zsófia Németh ◽  
Bence Molnár ◽  
Csaba Pánczél ◽  
Péter Böröcz
Keyword(s):  
Laboratory Test ◽  
Detailed Comparison ◽  
Vertical Vibration ◽  
Frequency Range ◽  
Delivery Methods ◽  
Test Environment ◽  
Business To Consumer ◽  
Safe Transport ◽  
Sales Model ◽  
Express Delivery

Courier express parcel (CEP) shipments become one of the most important delivery methods in the Business-to-Consumer sales model. This paper observed and analyzed the vertical vibration levels that occur in stacked and unsecured parcels during express delivery versus the simulation in the laboratory. At the end, a detailed comparison is reported between the field and laboratory vibration levels (based on standard PSD test profile) in the frequency range of 1 – 200 Hz. For the measurement a three-layer stacked unit was used building from corrugated box samples. The result shows and analyzes the vibration levels in the stacked layers in comparison to the ISTA (International Safe Transport Association) vibration protocol where only a single parcel is required to be tested without any stacking configuration.

Apparent mass of the seated human body during vertical vibration in the frequency range 2–100 Hz

Ergonomics ◽  
2020 ◽  
Vol 63 (9) ◽  
pp. 1150-1163
Author(s):  
Yu Huang ◽  
Penglin Zhang ◽  
Shihao Liang
Keyword(s):  
Human Body ◽  
Vertical Vibration ◽  
Apparent Mass ◽  
Frequency Range

scholarly journals Numerical and experimental assessment of a typical brazilian footbridge

2018 ◽  
Vol 11 (5) ◽  
pp. 1025-1035
Author(s):  
G. N. DOZ ◽  
J. L. V. BRITO ◽  
A. BRASILIANO
Keyword(s):  
Critical Frequency ◽  
Natural Frequencies ◽  
Experimental Tests ◽  
Vertical Vibration ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Frequency Range ◽  
Precast Elements ◽  
Concrete Deck

Abstract For the range of medium spans, around 30 to 40m, composite footbridges are getting popular in Brazil. This kind of structure consists on longitudinal steel truss beams providing support for a concrete deck usually made of precast elements. Typical examples of these structures may be found in many cities in Brazil, especially in Brasilia where a large number of highways demanded a significant set of footbridges. Due to the amount of this kind of composite footbridges in Brazil, studies concerning their mechanical behavior are required in order to ensure pedestrian’s safety. For this end, in this paper, a typical Brazilian composite footbridge located in Brasilia is analyzed by means of experimental tests and computational modeling. The focus is the determination of natural frequencies and mode shapes. Strategies to correctly obtain the vertical modes are also discussed since vertical vibration is the main vibration problem expected for the tested footbridge. The obtained results showed that structural balance between stiffness and mass leads to natural frequencies out of the critical frequency range excited by pedestrians in normal use, although the idea was not to measure how these parameters, mass or stiffness, could influence the model. Moreover, Finite Element models were evaluated comparing complexity versus accuracy to predict modal parameters.

Vibration Performance in Frequency Domain of CRTS I Double-Block Ballastless Track

2017 ◽  
Author(s):  
Feng Dai ◽  
Ying Zhu ◽  
Xueyi Liu
Keyword(s):  
Decay Rate ◽  
Frequency Domain ◽  
High Frequency ◽  
Structural Characteristics ◽  
Superposition Principle ◽  
Vertical Vibration ◽  
High Frequency Range ◽  
Frequency Range ◽  
Ballastless Track ◽  
Vibration Performance

According to the structural characteristics of the double-block track, using the Green’s function and superposition principle, the analytical model of the vertical vibration of the double-block track in frequency domain was established to analyze the responses of the double-block track in frequency domain and the influences of fastener stiffness, bedplate thickness and subgrade supporting stiffness on it. The results show that there are three obvious peaks for the rail mobility which are caused by bedplate resonance (35 Hz), rail resonance (200 Hz) and pinned-pinned resonance (1 kHz). Within the frequency range of less than 35 Hz, the bedplate mobility is determined by the bedplate supporting stiffness. Also the bedplate vibration decay rate increases with the increasing frequency. The bedplate resonance and wheel-rail coupling resonance have the most significant effect on the bedplate displacement. The frequency range where the rail high vibration decay rate lies gets wider with the larger fastener stiffness. Increasing the bedplate mass cannot attenuate its vibration in the mid-high frequency range.

Field Measurement and Analysis of Vibration Response in the Metro Shield Tunnel with Straight Joint

2013 ◽  
Vol 838-841 ◽  
pp. 1363-1369
Author(s):  
Ming Yu Li ◽  
Yuan Cheng Guo
Keyword(s):  
Response Time ◽  
Vertical Vibration ◽  
Vibration Response ◽  
Structural Vibration ◽  
Shield Tunnel ◽  
Frequency Range ◽  
Vibration Acceleration ◽  
Steel Spring ◽  
Measurement And Analysis ◽  
Standard Block

Appling the M8 as the monitor objects and choosing the single-round shield tunnel with or without the steel spring floating slab and the DOT shield tunnel with straight joint as the research objects, the vertical vibration response of the track bed and the standard block in different conditions was compared. The peak vibration acceleration of two measuring points and vibration response time of the standard block in the DOT is smaller compared with the DOT and the single-round shield tunnel when a single train is through the monitoring section. Vibration response time and intensity of the DOT structure is increasing with two trains intersection. Compared to the other two shield tunnels, structural vibration response of the single-round shield tunnel is significantly decreased by the isolation effect of steel spring floating slab. For the vibration acceleration of the track bed and the standard block in the three types of shield tunnels, spectrum range is 0Hz~150Hz, and peak acceleration is in the same frequency range, which is 35Hz~70Hz. Peak vibration acceleration of the track bed is greater than that of the standard block.

scholarly journals Analysis of the Possibility of Using Acoustic Emission for Monitoring Technical Condition of the Fuel Injector in 3AL25/30 Engine

2018 ◽  
Vol 1 (1) ◽  
pp. 419-425
Author(s):  
Krzysztof Dudzik
Keyword(s):  
Acoustic Emission ◽  
Laboratory Test ◽  
Good Condition ◽  
Signal Amplitude ◽  
Normal Operation ◽  
Engine Fuel ◽  
Fuel Injector ◽  
Frequency Range ◽  
Time Duration ◽  
Laboratory Test Results

Abstract Acoustic emission method (AE) can be used for the diagnosis of machine parts such as, for example: fuel injectors. This paper presents the methodology and research results of 3AL25/30 engine fuel injector. During research was studied one injector in good condition and second with simulated failure involving closing 2 of 9 holes of the injector tip. Research was carried out on a laboratory test stand using a set of acoustic emission Vallen System. This set included: 4 channel signal recorder AMSY 6, two measurement modules ASIP-2/S, preamplifier with a frequency range 20 kHz-1 MHz and the strengthening of 34 dB, AE signal measurement sensor type VS 150M, with a frequency range 100-450 kHz. During the study, the acoustic emission (AE) generated by tested injector was recorded. The following parameters were determined: amplitude, rise time, duration time, total time, number of events – hits, the effective value of the signal (RMS). Analysis of the results showed significantly longer total time of the injection in the case of damaged injector compared to the injector in good conditions. Signal amplitude was higher, however, the RMS signal reached approximately 3-times lower value for the injector with damaged tip. This means lower quality fuel atomization. Laboratory test results were compared with signals recorded on injectors installed in the engine. Analysis of the signals allowed detection damage of the injector installed in the engine during normal operation.

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