Water impact shock test system

The basic objective was to design, manufacture, and install a shock test system which, in part, would have the ability to subject test articles weighing up to 1,000 pounds to both half sine and/or full sine pulses having peak levels of up to 50 G's with half sine pulse durations of 100 milliseconds or full sine period duration of 200 milliseconds. The tolerances associated with the aforementioned pulses were +20% and -10% for the peak levels and plus or minus 10% for the pulse durations. The subject shock test system was to be capable of accepting test article sizes of up to 4 feet by 4 feet mounting surface by 4 feet in length

Aeration Effects on Impact: Drop Test of a Flat Plate

Verbatim reproduction or republication of the papers or articles or part of the articles (e.g., figures or tables) by their authors, after the publication or presentation at the ISOPE meetings and journal, is permitted by the International Society of Offshore and Polar Engineers (ISOPE), provided the full credit is given to the authors, to the publisher, The International Society of Offshore and Polar Engineers (ISOPE), and to the Conference, Symposium or Journal - more specifically not to remove the copyright imprint on page 1 of the paper. The permission does not extend to copying for resale and to re-copyrighting the whole or part of the papers. Posting on your organization's website of the paper(s) you specified is allowed only where only your organization's employees including the students can view free of charge the paper authored or co-authored by your organization's employees, and www.isope.org is provided for the paper(s) in the ISOPE proceedings or journals. Regards, Prof. Jin S Chung Executive Director isope, 495 North Whisman Road, Suite 300 Mountain View, California 94043-5711, USA T 1-650-254-1871; F 1-650-254-2038; [email protected] [email protected], www.isope.org www.deepoceanmining.orgAeration effects on impact have been investigated by dropping a flat plate onto the water surface, in which the water is aerated to various degrees. An experimental study has been carried out in the newly commissioned Ocean Basin at Plymouth University’s COAST Lab. The falling block comprises a rigid impact plate connected to two driver plates and its total mass can be varied between 32 kg and 52 kg. The impact plate is 0.25m long, 0.25 m wide and 0.012 m high. The impact velocity is varied between 4 m/s and 7 m/s. Preliminary results of the impact tests are presented here. Visualised results show that there are significant differences between jet formation after impact of the plate in pure water and in aerated water. There is significant reduction of the maximum pressures from those measured in pure water to those measured in aerated water

Modelling of impact damage and permanent indentation on laminate composite plate

This paper deals with impact damage and permanent indentation modelling. A model enabling the formation of damages developing during a low velocity / low energy impact test on laminate composite panels has been elaborated. The different impact damages developing during an impact test, i.e. matrix cracking, fibres failure and interfaces delamination, are simulated. The interlaminar damages, i.e. interfaces delamination, are classically simulated thanks to interface finite elements based on the fracture mechanics. The particularity of this model is to account for the intralaminar damages, i.e. matrix cracks, thanks to interface finite elements which respect their discontinue character. These interface elements allow equally to simulate the permanent indentation during the impact unloading. This impact mark modelling is very original in the literature, and should allow to entirely design a composite structure thanks to impact damage tolerance

Can the standard impact tests become a true materials evaluation tool?

Impact resistance constitutes one of the most popular quality control tools for polymeric materials and plastic finished parts. There are a number of standard impact test methods devoted to evaluate the impact response of polymeric materials (e.g., tensile-impact, Charpy and Izod tests, falling weight, Gardner, etc.). Nevertheless, to the questions: which test to use? how the different toughness measurements are related between each other? straightforward answers cannot be given. The shortcomings of standardized impact tests were recognized long ago: these tests are unable to generate an ‘actual material property’.Fil: Frontini, Patricia Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Pre-test session impact on the effectiveness assessment of a fire safety game

In recent years, critiques have been formulated regarding current evaluation methods of DGBL (digital game-based learning) effectiveness, putting the validity of certain results in doubt. An important point of discussion in DGBL effectiveness studies is whether or not a pre-test should be administered, as it can lead to practice effects and pre-test sensitization, threatening internal validity of the results. The present study aims at testing if the administration of a pre-test has a direct influence on post-test scores and/or makes participants more receptive to the intervention. For this purpose, an effectiveness study of a fire safety training in a hospital was conducted using a Solomon four-group design. The experimental groups received a game-based intervention (n= 65) of which 34 participants received a pre-test and 31 did not. The control groups received traditional classroom instruction (n=68), of which 39 participants received a pre-test and 29 did not. A 2x2 ANOVA was used to explore the practice effect and the interaction between the pre-test and the intervention. An interaction effect between pre-test and intervention is detected. More specifically, this interaction takes place in the traditional classroom group, indicating pre-test sensitization. In the traditional classroom context, the pre-test makes the participants more sensitive to the content treated in the intervention while administration of a pre-test does not influence outcomes of the DGBL treatment. When the administration of a pre-test influences the control group's receptivity to the treatment, but not the experimental group, results of an effectiveness study may be biased. This is especially relevant in the DGBL field as often, non-significant differences between DGBL and more traditional methods are reported. Therefore, further research should take this into account and look for possible solutions to solve this discrepancy

Impact behaviour of nylon-rubber blends: 5. Influence of the mechanical properties of the elastomer

Blends of 90wt% nylon-6 and 10wt% impact modifier were prepared. As impact modifiers were used: EPDM (ethylene propylene diene monomer) rubber, EPM (ethylene propylene monomer) rubber, polyethylene, four poly(ether esters) and some commercial impact modifers. EPDM, EPM and polyethylene were functionalized with maleic anhydride. The mechanical properties of the impact modifiers were tested with both a torsion pendulum test and a tensile test. The notched impact strength of the blends was measured as a function of temperature. The relation between the mechanical properties of the elastomer and the impact behaviour of the elastomer-modified nylon-6 was studied while taking into account the effect of the rubber particle size. The type of impact modifier was found to have a strong effect on the impact behaviour of the blend. The rubber particles do not toughen nylon-6 by acting as stress concentrators

Improved impact performance of marine sandwich panels using through-thickness reinforcement: Experimental results

This paper presents results from a test developed to simulate the water impact (slamming) loading of sandwich boat structures. A weighted elastomer ball is dropped from increasing heights onto rigidly supported panels until damage is detected. Results from this test indicate that honeycomb core sandwich panels, the most widely used material for racing yacht hulls, start to damage due to core crushing at impact energies around 550 J. Sandwich panels of the same areal weight and with the same carbon/epoxy facings but using a novel foam core reinforced in the thickness direction with pultruded carbon fibre pins, do not show signs of damage until above 1200 J impact energy. This suggests that these will offer significantly improved resistance to wave impact. Quasi-static test results cannot be used to predict impact resistance here as the crush strength of the pinned foam is more sensitive to loading rate than that of the honeycomb core

Testing the foreign aid-led growth hypothesis in West Africa

This paper assesses the foreign aid-led growth hypothesis in a panel of West African countries using panel cointegration techniques ( Pendroni Residual Cointegration Test, Error Correction Model, Johansen Fisher Panel Cointegration Test) and then on a country-by-country basis using time series cointegration techniques (Engle-Granger test, Error Correction Model , Johansen system cointegration test). The panel cointegration results indicate a long run relationship between aid and growth in the whole panel. For the individual countries, at least one test showed evidence of this long run relationship. Granger causality tests were done for the whole panel and then for each country individually to establish direction of causality between foreign aid and economic growth. There is evidence of unidirectional causality from foreign aid to economic growth, from economic growth to foreign aid and there are cases where both variables are independent. A simplified variation of the Chenery and Strout Two-Gap Model was estimated to test the impact of foreign aid and selected explanatory variables on economic growth in countries where aid was found to granger cause growth and this impact varied from country to country

Variation aware analysis of bridging fault testing

This paper investigates the impact of process variation on test quality with regard to resistive bridging faults. The input logic threshold voltage and gate drive strength parameters are analyzed regarding their process variation induced influence on test quality. The impact of process variation on test quality is studied in terms of test escapes and measured by a robustness metric. It is shown that some bridges are sensitive to process variation in terms of logic behavior, but such variation does not necessarily compromise test quality if the test has high robustness. Experimental results of Monte-Carlo simulation based on recent process variation statistics are presented for ISCAS85 and -89 benchmark circuits, using a 45nm gate library and realistic bridges. The results show that tests generated without consideration of process variation are inadequate in terms of test quality, particularly for small test sets. On the other hand, larger test sets detect more of the logic faults introduced by process variation and have higher test quality

Solid rocket booster water impact test

Water impact drop tests were performed on the space shuttle solid rocket boosters (SRB). Peak water impact pressures and pressure/time traces were measured for various impact velocities using a two-dimensional, full-scale SRB aft skirt internal ring model. Passive burst disc-type pressure transducers were calibrated for use on flight SRB's. The effects on impact pressure of small ring configuration changes and application of thermal protection system cork layers were found to be negligible