scholarly journals Estimating Passive Stress Acting on a Grain Entrapment Victim’s Chest

2018 ◽  
Vol 24 (3) ◽  
pp. 113-126
Author(s):  
Salah F. Issa ◽  
Carl Wassgren ◽  
Charles V. Schwab ◽  
Richard Stroshine ◽  
William E. Field
Keyword(s):  
Stress State ◽  
Testing Machine ◽  
Full Scale ◽  
Experimental Results ◽  
Testing Device ◽  
Active Stress ◽  
Farm Safety ◽  
Passive Pressure ◽  
Criterion Testing ◽  
Passive Stress

Abstract. Grain entrapments remain a major concern in the grain industry, with 1,100 incidents documented since the 1970s. One particular concern is the ability of a victim to breathe while entrapped in grain. Anecdotal reports suggest that victims struggle to breathe when entrapped in grain to a depth that covers their chests, yet some evidence indicates that victims should be able to breathe normally as long as their airways are not blocked regardless of depth. The hypothesis for this discrepancy is that previously published experiments measured an active stress state in the grain, while a person breathing also experiences a passive stress state during inhalation. The passive stress is significantly larger than the active stress. The objective of this study was to measure the passive stress when pushing against grain, such as during inhalation, and compare it to active stress state measurements. An MTS Criterion testing machine, which is a force deformation testing device, was used to push a block horizontally against a column of grain and record the force and displacement during the movement. The measured passive stress was calculated from the force and displacement values and ranged from 9.4 to 11.0 kPa at a depth of 20 to 30 cm. These values are three to four times larger than previously published measurements of stresses at similar depths. This result indicates that the discrepancy between experimental results and anecdotal reports is most likely due to the type of stress state experienced in grain entrapment. Findings imply that the pressures on the victim’s chest during entrapment are sufficient to cause breathing difficulties or crush/positional asphyxiation in some cases. A full-scale study is recommended. Keywords: Active pressure, Corn pressure, Farm safety, Grain rescue, Passive pressure, Rib cage.

Modal Strain Energy Based Damage Detection Applied to a Full Scale Composite Helicopter Blade

2013 ◽  
Vol 569-570 ◽  
pp. 457-464 ◽  
Author(s):  
Fabio Luis Marques dos Santos ◽  
Bart Peeters ◽  
Herman van der Auweraer ◽  
Luiz Carlos Sandoval Góes
Keyword(s):  
Structural Health Monitoring ◽  
Damage Detection ◽  
Health Monitoring ◽  
Rotor Blade ◽  
Strain Energy ◽  
Full Scale ◽  
Experimental Results ◽  
Main Rotor ◽  
Helicopter Blade ◽  
Main Rotor Blade

The use of composites in the aircraft industry has generated a great need for structural health monitoring and damage detection systems, to allow for safer use of complex materials. Such is the case with helicopter blades - these components nowadays are mostly composed of carbon fiber or glass fiber reinforced plastics laminates, epoxy and honeycomb filled core structures. The use of composite materials on the main rotor blade also allows for more complex and efficient shapes to be designed, but at the same time, their use requires an additional effort when it comes to structural monitoring, since damage can occur and go unnoticed. This work presents experimental results for structural health monitoring method based on strain energy. The test subject is a full-scale composite helicopter main rotor blade, which is a highly flexible, slender beam that can display unusual dynamic behavior with orthotropic behavior. This damage detection method is based on the modal strain properties, and a damage detection index is used to identify and quantify damage. A test setup was built to carry out an experimental modal analysis on the main rotor blade. For that purpose, a total of 55 uniaxial accelerometers were used on the helicopter blade to measure the displacement modes of the structure. To compute the strain modes from the displacement modes, central differences approximation is used. Damage is introduced on the blade by attaching a small mass to two different locations. Experimental results show the possibility of locating damage in this case.

Lateral Load Capacity and Passive Resistance of Full-Scale Pile Group and Cap

2000 ◽  
Vol 1736 (1) ◽  
pp. 24-32 ◽  
Author(s):  
Kyle M. Rollins ◽  
Andrew E. Sparks ◽  
Kris T. Peterson
Keyword(s):  
Load Capacity ◽  
Pile Group ◽  
Lateral Load ◽  
Full Scale ◽  
Dynamic Resistance ◽  
Back Side ◽  
Passive Resistance ◽  
Passive Pressure ◽  
Pile Cap ◽  
Measured Resistance

Static and dynamic (statnamic) lateral load tests were performed on a full-scale 3 × 3 pile group driven in saturated low-plasticity silts and clays. The 324-mm outside diameter steel pipe piles were attached to a reinforced concrete pile cap (2.74 m square in plan and 1.21 m high), which created an essentially fixed-head end constraint. A gravel backfill was compacted in place on the back side of the cap. Lateral resistance was therefore provided by pile-soil-pile interaction as well as by base friction and passive pressure on the cap. In this case, passive resistance contributed about 40 percent of the measured static capacity. The measured resistance was compared with that computed by several techniques. The log-spiral method provided the best agreement with measured resistance. Estimates of passive pressure computed using the Rankine or GROUP p-y curve methods significantly underestimated the resistance, whereas the Coulomb method overestimated resistance. The wall movement required to fully mobilize passive resistance in the dense gravel backfill was approximately 0.06 times the wall height, which is in good agreement with design recommendations. The p-multipliers developed for the free-head pile group provided reasonable estimates of the pile-soil-pile resistance for the fixed-head pile group. Default p-multipliers in the program GROUP led to a 35 percent overestimate of pile capacity. Overall dynamic resistance was typically 100 to 125 percent higher than static; however, dynamic passive pressure resistance was over 200 percent higher than static.

Noise-related roughness of railway wheel treads-full-scale testing of brake blocks

2000 ◽  
Vol 214 (2) ◽  
pp. 63-77 ◽  
Author(s):  
M Petersson
Keyword(s):  
Cast Iron ◽  
Hot Spots ◽  
Testing Machine ◽  
Full Scale ◽  
Spatial Distributions ◽  
Material Transfer ◽  
Railway Wheel ◽  
Rolling Noise ◽  
Brake Block ◽  
Abrasive Property

Results from full-scale tread braking experiments on an inertia dynamometer (brake testing machine) are presented. Eighteen prototypes of brake blocks are investigated. Two braking characteristics relating to the influence of the blocks on the wheel tread are studied: generation of hot spots and generation of roughness (corrugation, waviness). Wheel tread temperatures are measured during braking using an infrared (IR) technique. The wheel roughness is measured after each brake cycle when the wheel has cooled down. A roughness indicator, RλCA, relates measured roughness to expected rolling noise as generated by the wheel in operation. A correlation between the spatial distributions of temperatures and roughnesses is normally found: stronger for cast iron blocks and composition blocks and weaker for sinter blocks. The cast iron blocks are found to produce high tread roughness levels, partly owing to material transfer from brake block to wheel tread. The composition blocks are found to result in lower roughness levels than the cast iron blocks. Finally, the sinter metal blocks are found to lead to the lowest roughness levels, a fact which is probably due to the abrasive property of these blocks. Friction coefficients during braking are also measured.

scholarly journals Random-type Fatigue Testing Machine Devised for Trial-Experiment and Some of its Experimental Results

1961 ◽  
Vol 10 (99) ◽  
pp. 1032-1045
Author(s):  
Hiroshi NAKAMURA ◽  
Saburo YUDA ◽  
Jusaku SEKITA ◽  
Kazuyoshi WATANABE
Keyword(s):  
Fatigue Testing ◽  
Testing Machine ◽  
Experimental Results

Plastic Flow Stress and Constitutive Model for H96 Brass Alloy

2015 ◽  
Vol 782 ◽  
pp. 130-136 ◽  
Author(s):  
Ping Zhou ◽  
Wei Guo Guo ◽  
Hai Hui Wu
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Plastic Flow ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Experimental Results ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Brass Alloy ◽  
Plastic Flow Stress

To explore the thermo-mechanical response of H96 brass alloy, the quasi-static (universal-testing machine) and dynamic (the split Hopkinson pressure bar apparatus) uniaxial compression experiments have been performed under the temperatures from 293 K to 873 K and the strain rates from 0.001 s-1 to 6000 s-1, and the strains over 60% are obtained. Results show that, H96 brass alloy has strong strain hardening behavior, and it becomes weaker with the increasing temperature. In addition, this alloy is sensitive to strain rates; and, it has temperature sensitivity, the dynamic strain aging occurs at the temperature of 473 K and a quasi-static strain rate of 0.001 s-1. Based on the thermal activation dislocation mechanism, paralleled with the experimental results, a plastic flow constitutive model with the physical conception is developed. The model is suitable to predict the plastic flow stress at different temperatures and strain rates. According to comparing results, the model predictions are in good agreement with the experimental results.

Some Experimental Results on Internal Fire Whirls in a Vertical Shaft

2013 ◽  
Author(s):  
Y. Gao ◽  
G. W. Zou ◽  
S. S. Li ◽  
W. K. Chow
Keyword(s):  
Full Scale ◽  
Pool Fire ◽  
Experimental Results ◽  
Vertical Shaft ◽  
Remote Site ◽  
Scale Modeling ◽  
Key Factor ◽  
Fire Whirl ◽  
Real Scale

Earlier studies on burning a pool fire in a vertical shaft model indicated that appropriate sidewall ventilation provision is a key factor for the onset of an internal fire whirl. Experiments on burning a pool fire inside a real-scale shaft model of 9 m tall were performed to further investigate the swirling motion. The full-scale modeling burning tests were carried out at a remote site in China. Four different ventilation openings were arranged. Results of onsetting of internal fire whirls for the four tests will be reported.

Experimental Study on Full-Scale Segment Model of Huaian Cable-Stayed Bridge Pylon

2011 ◽  
Vol 243-249 ◽  
pp. 1866-1870 ◽  
Author(s):  
Hong Yuan Tang ◽  
Shao Ping Meng
Keyword(s):  
Experimental Study ◽  
Stress Distribution ◽  
Theoretical Analysis ◽  
Full Scale ◽  
Experimental Results ◽  
Horizontal Load ◽  
Experiment Study ◽  
Segment Model ◽  
Cable Stayed Bridge

Through experiment study on full scale segmental model of Huaian bridge pylon, the stress distribution in the segmental model under the U shaped tendons and the horizontal load was measured. At the same time, the critical cracking load and the coefficient cracking safety class of the anchorage zone were obtained. At last, the theoretical analysis was compared with the experimental results, the theory agreed with the experiment well.

scholarly journals Influence of moisture content on pressure ratio of rape seeds

2012 ◽  
Vol 50 (No. 1) ◽  
pp. 11-14 ◽  
Author(s):  
R. Rusinek ◽  
J. Łukaszuk
Keyword(s):  
Moisture Content ◽  
Pressure Ratio ◽  
High Ratio ◽  
Experimental Results ◽  
Vertical Pressure ◽  
Loading And Unloading ◽  
Four Levels ◽  
Passive Stress

The pressure ratio of rape seeds was determined for four levels of moisture content in a model silo. The silo was 0.6 m in diameter and 0.6 m high. Ratio of horizontal to vertical pressure and distributions of local horizontal to vertical pressure along the radius of the floor in the model silo were determined for cycles of loading and unloading simulated conditions observed in a silo (in a range of 0–13 kPa). The sample was poured into the model silo through centrally located spout, without vibration or other compacting actions. The pressure ratio rape seeds generally decreased with an increase in moisture content. Experimental results were compared with simplified approximation recommended by the Eurocode 1 (2003) and theoretical values obtained for active and passive stress case.

Numerical Simulation of the Added Mass of the Fluid Adjacent to the Ship Hull in Vibration Measured During Sea-Trials in Tanker Ships to be Converted to Offshore Construction Vessel

2012 ◽  
Author(s):  
Severino Fonseca Silva Neto ◽  
Silvia Ramscheid Figueiredo ◽  
Marta Cecilia Tapia Reyes ◽  
Luiza de Mesquita Ortiz
Keyword(s):  
Numerical Model ◽  
Kinetic Energy ◽  
Natural Frequencies ◽  
Three Dimensional ◽  
Added Mass ◽  
Vertical Vibration ◽  
Full Scale ◽  
Experimental Results ◽  
Vibration Velocity ◽  
Main Engine

This study aims to analyze the influence of the kinetic energy of the fluid adjacent to the hull of a tanker ship in its vertical vibration frequencies, comparing them with experimental measurements obtained during sea-trials. The one-dimensional modeling of ships allows the construction of simple finite element models from the structural elements of its master section, with structural and added masses, and their frequencies are verified by full-scale measurements, during the sea-trials. The numerical results of these models, with the value of the effective shear area as a fraction of the total area of the strength steel are compared to those obtained in full-scale measurements during sea trials of an oil tanker to be converted to Offshore Construction Vessel. Global vibration measurements were carried out in two of the six ships with the same hull. Accelerometers were installed in eleven strategic points of each hull. Vibration data acquisition was performed simultaneously for these locals in thirteen rotations of the main engine. The amplitude spectra of vibration velocity on the frequency range of measurements were obtained and were plotted graphs of the evolution of the main harmonics, depending on the rotation of the main engine, in order to identify four natural frequencies of the overall vibration of the hull, which were compared to the numerical model. The calculation is performed by the added mass formulations from Burrill, Todd, Kumay and Lewis/Landweber [8] curves, including in all three-dimensional effect by Townsin [17] coefficients, which is checked against the experimental results. The comparison between numerical and experimental results allows assessing the influence of the kinetic energy of the fluid surrounding the hull in the natural frequencies of vibration of the numerical model of the tanker ship and simulating their dynamic behavior after conversion in Offshore Construction Vessel.

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