Parallel Plate Compression Test Research Articles

Parallel-plate compression test for soft materials: confocal microscopy-assisted ferrule-top nanoindentation.

The parallel-plate compression test is one of the simplest ways to measure the mechanical properties of a material. In this test, the Young's modulus ( ) and the Poisson's ratio ( ) of the material are determined directly without applying any additional modelling and parameter fitting in the post-processing. This is, however, limited when dealing soft biological materials due to their inherent properties such as being inhomogeneous, microscopic, and overly compliant. By combining an interferometry-assisted parallel-plate compression system and a confocal microscope, we were able to overcome these limitations and measure the (315 52 Pa) and (0.210 0.043) of fixated and permeabilized bovine oocytes.

A Discrete Multi-Physics Model to Simulate Fluid Structure Interaction and Breakage of Capsules Filled with Liquid under Coaxial Load

This paper investigated the mechanical response (including breakage and release of the internal liquid) of single core–shell capsules under compression by means of discrete multi-physics. The model combined Smoothed Particle Hydrodynamics for modelling the fluid and the Lattice Spring Model for the elastic membrane. Thanks to the meshless nature of discrete multi-physics, the model can easily account for the fracture of the capsule’s shell and the interactions between the internal liquid and the solid shell. The simulations replicated a parallel plate compression test of a single core–shell capsule. The inputs of the model were the size of the capsule, the thickness of the shell, the geometry of the internal structure, the Young’s modulus of the shell material, and the fluid’s density and viscosity. The outputs of the model were the fracture type, the maximum force needed for the fracture, and the force–displacement curve. The data were validated by reproducing equivalent experimental tests in the laboratory. The simulations accurately reproduced the breakage of capsules with different mechanical properties. The proposed model can be used as a tool for designing capsules that, under stress, break and release their internal liquid at a specific time.

Relation between viscosity and flow characteristics in uni-directional CF/PA6 laminates near the melting point

In this study, the viscosity of unidirectional carbon fiber reinforced thermoplastic (CFRTP) laminates near their melting point was evaluated to discuss the relationship between the thermal fusion conditions and the flow of the fibers and matrix. The laminates were regarded as a fluid flowing in the direction perpendicular to the fibers. The microscopic flow of the fibers and matrix was observed during a parallel plate compression test conducted near the melting point. On the basis of this observation, the viscosity and flow properties were evaluated by the finite element method (FEM). The results of the parallel plate compression test showed that the test conditions and the decrease in the thickness of the laminates are related to the apparent viscosity of the unidirectional plate. In addition, cracks in the direction of the maximum shear stress were detected via in situ observation near the melting point of the matrix. The occurrence of this phenomenon depended on the apparent viscosity of the unidirectional laminates, and it was found that no cracks occurred when the apparent maximum viscosity of the unidirectional laminates was lower than a threshold.

Abstract 999: In vivo breast tumor stiffness and vascular drug delivery recapitulated in a microfluidic tumor-on-a-chip

Abstract Biomimetic tissue engineered microfluidic cancer models offer a higher degree of spatial, temporal and structural precision in controlling the physical parameters and component characteristics of the native tumor microenvironment (TME). Current models working to establish a biomimetic in vitro breast TME are limited by their ability to recapitulate various degrees of in vivo complexities and poor correlation of the diffusional gradients of oxygen, nutrients and anti-cancer drugs. To establish a model and address these challenges, we have used poly(ethylene glycol)-fibrinogen (PEG-Fb) as our biomimetic material to engineer 3D breast tumor tissues and recapitulate the mechanical stiffness of core, midpoint and peripherial zones of the native tumor in a vascularized microfluidic chip. To assess the mechanical stiffness, the in vivo breast tumor (MDA-MB-231 flank xenograft in Athymic nude mice) and engineered tumor constructs were subjected to parallel plate compression test using Cell Scale Microsquisher and the resulting force versus displacement data was acquired to calculate Young’s modulus. Tumor mimetic (“high perfusion chip” (HPC) and “low perfusion chip” (LPC), differ with respect to the vascular network surrounding their respective primary and secondary tumor compartments were used in this study. Breast cancer-associated endothelial cells (hBTEC) were seeded in the vascular network and allowed to form a lumen. Metastatic breast cancer cells MDA-MB-231/ human foreskin fibroblast BJ5ta (ATCC) cells were mixed with polymer precursor solution containing PEG-Fb and Eosin Y. The precursor was loaded into the primary tumor compartment and cross-linked for 2 minutes under visible light. Stiffness was modulated by adding poly(ethylene glycol) diacrylate (PEGDA) to the polymer precursor for recapitulating the different zones of the in vivo tumor. hBTEC media was perfused through the endothelial cell networks were continuously monitored for cell behavior and metastasis. In vivo breast tumor stiffness at core, midpoint and periphery was found to be within the range of the 3D engineered breast tumor tissues with time in culture through day 29. In the vascularized microfluidic chip, cell laden biomaterial was incorporated, the cancer cells were observed to undergo key events of the TME such as intravasation, circulating tumor cells in the endothelial vascular channel, adherence and migration to the secondary chamber resulting in metastasis. In the native TME there are regional differences in drug diffusion; TRITC dextran (4.4 kDa) was administered at a constant flow rate through the chips’ vascularized networks and found to have vascular network geometry and engineered tumor construct stiffness dependent differences in diffusion into the primary tumor chamber, mimicking the in vivo phenomena. Citation Format: Benjamin Anbiah, Iman Hassani, Nicole Habbit, Lani Jasper, Deborah Ramsay, Balabhaskar Prabhakarpandian, Robert Arnold, Elizabeth Lipke. In vivo breast tumor stiffness and vascular drug delivery recapitulated in a microfluidic tumor-on-a-chip [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 999.

COMBINED USE OF PARALLEL-PLATE COMPRESSION AND FINITE ELEMENT MODELING TO ANALYZE THE MECHANICAL PROPERTIES OF INTACT PORCINE LENS

The objective of this study is to explore the feasibility of a compression test for measuring mechanical properties of intact eye lenses using novel parallel plate compression equipment to compare the accuracy of implementing a classical Hertzian model and a newly proposed adjusted Hertzian model to calculate Young’s modulus from compression test results using finite element (FE) analysis. Parallel-plate compression tests were performed on porcine lenses. An axisymmetric FE model was developed to simulate the experimental process to evaluate the accuracy of using the classical Hertzian theory of contact mechanics as well as a newly proposed adjusted Hertzian theory model for calculating the equivalent Young’s modulus. By fitting the force-displacement relation obtained from FE simulations to both the classical and adjusted Hertzian theory model and comparing the calculated modulus to the input modulus of the FE model, the results demonstrated that the classical Hertzian theory model overestimated the Young’s modulus with a proportional error of over 10%. The adjusted Hertzian theory model produced results that are closer to original input values with error ratios all lower than 1.29%. Measurements of three porcine lenses from the parallel plate compression experiments were analyzed with resulting values of Young’s modulus of between 3.2[Formula: see text]kPa and 4.3[Formula: see text]kPa calculated. This study demonstrates that the adjusted Hertzian theory of contact mechanics can be applied in conjunction with the parallel-plate compression system to investigate the overall mechanical behavior of intact lenses.

EMPIRICAL STUDY OF THE CHARACTERISTICS OF AFZELIA AFRICANA SEED UNDER COMPRESSIVE LOADING

Afzelia Africana seeds were subjected to quasi-static parallel plate compression test, using Monsanto Tensometer. The loading orientations were horizontal, vertical and edge-to-edge loading positions at four different moisture content levels of 10.6%, 12.8%, 15.2% and 18.4% wet basis (wb). Slight variations were observed in the means of the physical characteristics at varying moisture content in the range of 10.6% to 18.4%. Loading position was shown to have significant effect on all the mechanical properties studied. The rupture force increased with increase in moisture content in horizontal and vertical loading but did not show consistent trend in variation when loaded on the edges. This value was 155.68N for vertical loading, 139.27 N for horizontal loading and 81.0 N for edge-to-edge loading. Hardness ranged from 6.97 to 6.92 N/mm for horizontal loading, 6.92 to 6.67N/mm for edge-loading and 6.99 to 6.93N/mm for vertical loading respectively in the moisture content range of 10.6 to 18.4% for all cases. Rupture energy varied from 104 to 416.33 N-mm on horizontal loading, 59.96to 241.82 on edge-loading and 190.125 to 419.171 Nmm on vertical loading respectively for the same range of moisture content. Toughness varied from 43.758 to 8.865 N-m/mm, 23.563 to 5.370 and 44.667 to 16.349 N-m/mm for horizontal loading, edge-edge orientation, and vertical loading respectively, for moisture content range of 10.6 to 18.4%.Modulusof Elasticity dropped from 35.657 to 28.133 N/mm2 for horizontal loading, from 51.443 to 14.59 for edge-to-edge loading and 38.087 to 41.04 N/mm2for vertical loading in the range of moisture content of 10.6 to 18.4% respectively. The data generated in this study can be applied when estimating the energy and force needed for shelling the seeds and in making useful suggestions on the loading condition that will demand the least energy for the operation and shelling. The physical properties are also useful in process design and analysis.  http://dx.doi.org/10.4314/njt.v36i3.42

폴리에틸렌 하수관 연결용 전기발포융착 이음관에 관한 연구

A electro-foaming fusion wrap fitting for polyethylene sewer pipe was built and foaming mechanism has been studied. A foaming sheet, supporting sheet and clamping band is assembled into a all-in-one structured electro-foaming fusion wrap fitting. To specify foaming and fusion of electro-foaming fusion wrap for PE sewer pipe, series of fusion tests were performed in various conditions. A parallel plate compression test up to 50 % of inner diameter deflection has been performed to check integrity of fusion quality and it was found that there were no visible signs of crack in wrapped area of fitting. Also air tightness test based on KS M 3511-2 has been performed to evaluate perfectness of wrap fusion quality and we found there were no pressure drop up to 10 times higher value than KS standard regulation.

The effect of cooling rate and rapeseed oil addition on the melting behaviour, texture and microstructure of anhydrous milk fat

Anhydrous milk fat and blends containing up to 40% (w/w) rapeseed oil (RO) were crystallized using a slow (0.05 °C min−1) or fast (5 °C min−1) cooling rate. Melting behaviour was examined using differential scanning calorimetry, texture was analysed by parallel plate compression tests, microstructure was studied by confocal laser scanning microscopy, and solid fat content was measured by pulse-NMR. Fast cooling of the blends decreased the peak melting temperature of both high and low melting fractions of milk fat as the content of RO increased, while increasing RO combined with slow cooling did not affect melting behaviour. Solvent effects dominating in fast cooled samples are suggested to be responsible for the change in melting behaviour. The texture of fast cooled samples correlated with solid fat content. In slow cooled samples addition of RO decreased the hardness, which was ascribed to an increase in crystal cluster size.

Cardanol Based Matrix for Jute Reinforced Pipes

AbstractThe aim of this work is the development of composite pipes using renewable resources. The pipes, manufactured by filament winding technology, were obtained using an epoxy resin crosslinked with a cardanol based novolac as matrix and jute fibres as reinforcement. Cardanol is a natural oil extracted from the shell of the cashew (Anacardium occidentale L.) nut. An amount of natural materials higher than 50% by weight was achieved in the final composites. Tensile and parallel plate compression tests were carried out on the composite pipes.

Microstructure and rheological behavior of hypereutectic semi-solid Al–Si alloy under low shear rates compression test

Permanent mold cast cylindrical samples were reprocessed to form semi-solid billets of A390 Al–Si alloy, employing a thixocasting method. The billets were reheated to predetermined mushy zone temperatures and held isothermally during parallel plate compression tests. The deformation behavior of the billets was measured at different applied pressures, and fraction solids determined by the preheating temperature. The calculated viscosities confirmed pseudoplastic behavior of the semi-solid alloys and were correlated to the solid fraction and shear rate to illustrate the effect of metallurgical and process parameters on the viscosity and the consequent rheological behavior of these alloys.

The effect of dissolved titanium on the primary α-Al grain and globule size in the conventional and semi-solid casting of 356 Al–Si Alloy

The chemistry of molten alloy plays an important role on grain refining. Small addition of alloying elements reduces the grain size of the as-solidified structures to some degree depending on the alloy efficiency. The effect of dissolved Ti has been studied on the microstructure of Al–Si foundry alloys cast conventionally and by semi-solid casting routes. It is shown that Ti in solution could restrict the grains and globules size in both processes. A parallel plate compression test machine was employed to study the effect of dissolved Ti on the rheological behavior of the billets. It was confirmed billets with higher dissolved Ti-content have superior flow.

Comparison of Rheological Measurement Techniques for Semi-Solid Aluminium Alloys

Alloys of a specific microstructure exhibit a shear-rate history-dependent flow behaviour in the semi-solid state. Rheological studies have been carried out using various experimental techniques such as concentric cylinder rheometers of Couette or Searle type as well as capillary rheometers and parallel plate compression tests. With the Searle type rheometer and the capillary rheometer two different approaches of rheological measurement techniques are discussed and compared regarding advantages, potentials and its distinct characteristics. Experiments using the Searle type rheometer have been conducted under steady-state or oscillating conditions and have been used to verify time-dependency of step responses due to discontinuous or linear variances of the shear rate. These experiments provide all types of flow curve parameters as implemented in the numerical simulation. However the variances of the commonly used Couette and Searle type rheometers are limited to shear-rates which are significantly lower than that appearing in the technical thixo- or rheocasting processes. For that reason an additional experimental set-up with a horizontal slot capillary integrated in a shot-controlled high-pressure die-casting machine is used in order to examine flow properties at shear rate conditions similar to those in real thixocasting processes. After an initial examination of low temperature model alloys, such as PbSn15, the experimental set-up is then adjusted in order to obtain rheological data for light metal alloys such as Aluminium AlSi7Mg0.3. The Aluminium alloy is processed within each rheometer either as partially solidified or partially remelted in order to represent conditions of both, the conventional thixocasting and the lately introduced rheocasting process. Finally the appearance of physical phenomena which affects the accuracy of rheological experiments such as wall slip is considered for both types of rheometers.

Deformation behavior of semi-solid A356 Al–Si alloy at low shear rates: The effect of sample size

The rheological behavior of semi-solid metal slurries at low shear rates can be characterized by parallel plate compression tests of cylindrical discs where the height ( h) is much smaller than the diameter ( d) and the axial flow is assumed negligible or zero against the radial flow. In order to confirm the validity of required aspect ratio, two sets of cylindrical test samples with ( h/ d) of 0.4, d = 24 mm small discs, and 1.8, d = 75 mm billets, were prepared with similar microstructures. The small specimens were tested in a parallel plate squeezing flow rheometer to determine the viscosities which were compared to the viscosity values of samples (billets) with larger aspect ratios using a similar large scale apparatus. For the billets, rheocast samples, it was shown that the dendritic primary α-Al structure has the highest viscosity. The viscosity decreases when the structure comprises a rosette or globular morphology. Similar results were obtained for the discs, thixocast samples, where the specimens have similar initial microstructure. The results confirmed that for low shear rates, less than 10 −2 s −1, the viscosity of semi-solid alloy is dependent mainly on the morphology of the primary particles and not the sample size.

Nondestructive dynamic testing of apples for firmness evaluation

Abstract Two nondestructive dynamic test methods, low-mass impact and acoustic response, were tested and compared with destructive compression and penetration tests to evaluate apple firmness. The purpose of the study was to analyze the performance of the impact test methods for nondestructive firmness evaluation, and to assess whether the acoustic tests could add sorting capacity to low-mass impact testing in apples. A laboratory-instrumented impact hammer and a low-mass impact firmness sensor produced by Sinclair International (SIQ-FT) were used to perform the impact tests, and a piezoelectric-film transducer was applied for the acoustic tests. A new Sinclair internal quality index IQ and two conventional impact parameters C 1 and C 2 were extracted from the impact signals, and a firmness index FI was calculated from the acoustic signal of the samples. The nondestructive tests were followed by parallel-plate compression tests and Magness–Taylor penetration tests. Three apple varieties, ‘Golden Delicious’, ‘Starking Delicious’ and ‘Granny Smith’, were tested by the impact and acoustic methods. The performance of the experimental systems and the test methods were evaluated first by rubber ball calibration tests. The elastic modulus of all apples was well predicted by the acoustic firmness parameter FI ( R >0.91). The impact parameter IQ was equivalent to FI in predicting the elastic modulus of ‘Golden Delicious’, and less accurate in ‘Starking Delicious’ and ‘Granny Smith’. The conventional indices C 1 and C 2 performed similarly to the FI and IQ in the rubber balls and the ‘Golden Delicious’ tests, but failed to predict the elastic modulus of ‘Starking Delicious’ or ‘Granny Smith’ apples, probably because of their less uniform shape, and the sensitivity of these empirical parameters to test conditions. The changes of the penetration force during the test period were very low, and their correlation with the elastic modulus and the firmness parameters of all apples was poor. These previously reported findings might indicate that the Magness–Taylor penetration test is not an appropriate measure of apple firmness during shelf life. The test results indicated that the new SIQ-FT device and the IQ parameter offer a new technology that may overcome some basic difficulties associated with the low-mass impact test methods, which have been reported in the literature. The results also indicated that the acoustic method might add sorting capacity to the impact method in some apple varieties. Further R&D efforts are needed, however, to verify these results and adapt the acoustic method for on-line operation.

Objective Method for Measuring Firmness of Iceberg Lettuce

Traditional hand compression firmness scores of iceberg lettuce (Lactuca sativa L.) heads were compared with force-deformation data collected from parallel-plate compression tests conducted with a universal testing machine. Sample deformation was measured over a load range of 30 to 40 N. A quadratic response surface best described the relationship between hand firmness scores (1 to 5 scale) and three measurements of sample deformation (mm). Sample deformation was as precise as hand compression in measuring lettuce firmness, and it provided improved reproducibility by eliminating much of the human error. Although adequate for most firm heads, the predictive ability of the statistical model was weak for soft heads (when the hand firmness score was <2), and for heads with inconsistencies in firmness because of uneven leaf distribution. The minimum sample size required to determine accurately the mean firmness score (±0.5 units) of a population of harvested lettuce was ≈20 heads. This may be a disadvantage, since sampling one head requires ≈1.5 minutes. Overall, the instrument-based method measures lettuce firmness as precisely as the hand compression method, and provides a standardized, objective measurement for postharvest researchers when exchanging or reporting firmness data.

Stress release in oriented HIPS as observed by dynamic mechanical analysis

The transition from the glassy state to the rubbery state in a partially oriented high-impact polystyrene (HIPS) sample has been investigated by means of dynamic mechanical analysis (DMA), using three-point bending and parallel plate compression test modes. For samples without any thermal treatment an apparent increase of the storage modulus, E′( T), was observed near the onset of the calorimetric glass transition temperature, followed by a strong decrease due to the dynamic glass transition. This peak was attributed to the stress release of the oriented material and almost disappeared for an annealed sample. The compression experiments were found to be more sensitive to the stress release phenomena than flexural experiments. Several experiments at different frequencies (from 0.5 to 20 Hz) showed that both the area and the height of the E′( T) peaks increase linearly with the logarithm of frequency. The influence of the heating rate (for a fixed frequency – 1 Hz) was also analysed and the thermal calibration method used prior to those experiments is discussed. It was found that the strength of the E′( T) peaks decreases with increasing heating rate and the corresponding loss peaks, E"(T), shift to higher temperatures and become sharper.

Long-term flexible cable duct performance under load

This article presents results from the long-term creep and stress relaxation testing of single-wall high-density polyethylene (HDPE), twin-wall corrugated medium-density polyethylene (MDPE) and single-wall unplasticised polyvinylchloride (uPVC) ducts under parallel plate compression for up to 125 h at 25°C and 40°C. The ducts tested were all for use in cable television networks and were designed for direct burial underground in trench reinstatements. The results were extrapolated for longer performance assessments. The creep results appeared to be independent of the initial duct stiffnesses. The stiffness of the corrugated MDPE duct appeared to decrease with time by more than an initially less stiff single-wall uPVC duct. Corrugation effects upon the initial parallel plate compression test stiffness also disintegrated under stress relaxation; more pronounced load reduction was observed for the uPVC product.

Parallel plate compression tests on flexible cable ducts for use in trench reinstatements

This paper presents research on the parallel plate compression test for flexible ducts. The effects of variations in a duct's diameter, wall thickness and length are examined. The effects, upon a duct's parallel plate compressive stiffness, of strain rate and temperature are also assessed. Recommendations for parallel plate compression tests are provided in the form of corrections allowing direct comparison of results from different tests. Correlation between parallel plate compression test data and performance in trench reinstatements is presented.

Rapid Plastometry

Abstract The uses of plasticity tests, especially rapid simple tests, are discussed, with particular reference to the limitations imposed by the complex plastic behavior of unvulcanized rubbers and stocks, leading to the conclusion that simple tests are likely to be of use only for routine control of repeat, nominally identical batches. A summary is given of information collected from the industry to show under what conditions a plasticity test is required to be used in factory control. The efficiency of a plasticity test is defined, and a discussion given on how the type of instrument (rotation, extrusion or compression) and the conditions of a compression test affect both efficiency and rapidity, thus showing what conditions furnish the best form of test. It is concluded that the parallel-plate compression test is the most suitable, provided the test-piece is precompressed to a small thickness so that it can be quickly heated to the test temperature before applying the load; other factors considered are the size of compression plates and of test-piece, use of release medium (e.g., thin paper), degree of precompression, preheat period, load, compression period, and temperature. Existing rapid plastometers are described, including full details of the new Wallace modification of the Hoekstra instrument, which embodies the recommended conditions of test.

The Interpretation of Plasticity Measurements

Abstract After consideration of the various factors whose influence must be included in any complete assessment of the fundamental flow properties of uncompounded raw rubber, a comparison is made of results from various instruments. It is shown that a plot of log (shear stress) against log (strain rate) is straight or slightly curved at low shear rates, but may be markedly convex to the log stress axis at higher rates. Reference is made to the limitations of the methods of Scott for the interpretation of the results of parallel-plate compression tests; attempts to apply the Nutting equation to the large strains in the usual compression tests with rubber are shown theoretically, and by experiments on materials of known characteristics, to be invalid. Consideration of the instruments available for factory control purposes shows that the one figure obtained from conventional tests is inadequate for the evaluation of a new mix or even a new plasticizing or mixing technique, and alternative procedures are considered; for the control of nominally identical batches a single figure may be adequate. Finally, the essential requirements for research and control instruments are compared, and available instruments in each group surveyed in the light of the earlier discussion.