Limited Breakage Research Articles

Review of the Main Mechanical Testing Methods for Interlayer Characterization in Laminated Glass

In the last decades, the use of structural glass has increased exponentially. The reliability of brittle structural glass elements is considerably improved if laminated glass elements are chosen because, in this case, a redistribution of internal forces is permitted once a limited breakage occurs. Thus, instead of monolithic glass, composite materials consisting of two or more glass plies bonded together using a polymeric film as an interlayer are used. In the event of glass failure, because of the chemical bond between the different materials, the adhesion to the interlayer prevents glass fragments from scattering. To design structural elements, the definition of the mechanical features of the interlayer is necessary. However, several standards and techniques can be applied, considering the characterization of either the interlayer itself or the laminated glass. The paper reviews the main existing methods and focuses on the standard suggested by the CEN/TS 19100:2021, analyzing in detail the effect of the different parameters involved. A numerical model is presented to account for the effect of the stress level, glass, and interlayer thickness. Although the standard leaves a certain degree of freedom in choosing those parameters, in some cases the results can differ.

Analysis of Cipollino Verde marble wall decoration in Ephesos, Turkey, using geological reconstruction

Slabs of Cipollino Verde, composed of layered and folded marble from Euboea in Greece, decorated the hall of a Roman town house in Ephesos, Turkey in the second century AD. After excavation, the fragmented slabs were restored. Preservation of the dowels in the walls from which the slabs were originally suspended allowed reconstruction of the order in which they had been placed on the walls. The pattern of folded layering in the slabs in turn allowed 3D structural geological reconstruction of the folds, and reconstruction of the arrangement of slabs in the marble block, from where they were serially sectioned, using a slab saw. Investigation of geological fold alignment in the block revealed that 23–47% of the marble was lost in sawing and polishing, close to modern values. Comparison of the sequence of slabs on the walls and in the original block reveals the decoration strategy for the Roman hall. Slabs were placed in the sequence in which they had been cut from the block in book-matched fashion, with some rearrangement due to breakage of two slabs. Limited breakage was not due to sawing of slabs, but probably to the polishing process, or to transport of slabs. Analysis of ancient ornamental stone using geological 3D restoration techniques can provide important insights in the archaeology of stone working and trade.

Size reduction of CCZ polymetallic nodules under repeated impact fragmentation

Polymetallic nodules provide an alternative source of valuable metals. Nodules from the seabed of the Clarion Clipperton Zone (CCZ), a prospective mining area, are typically abundant at depths of around 5 ​km. Mining these nodules comprises excavation or pick-up of nodules and hydraulic transport of nodules from the seafloor to the surface. The particle size distribution of the nodules, an important design parameter, will change during transport under influence of different processes. One of these processes is impact fragmentation, especially occurring in centrifugal pumps. Recent research has led to improved understanding of impact fragmentation of polymetallic nodules, but quantification of the degradation process still is an open question due to scarcity of breakage data. In this paper we present a detailed analysis of nodule strengths and stresses occurring during impact and we propose an impact fragmentation model based on limited breakage data. The model is compared with the experiments and we comment on application of this model in engineering practice.

Caldera-forming eruptions of mushy magma modulated by feedbacks between ascent rate, gas retention/loss and bubble/crystal framework interaction

Caldera-forming eruptions of mushy silicic magma are among the most catastrophic natural events on Earth. In such magmas, crystals form an interlocking framework when their content reaches critical thresholds, resulting in the dramatic increase in viscous resistance to flow. Here, we propose a new mechanism for the ascent of mushy magma based on microstructural observations of crystal-rich silicic pumices and lavas from the Central Andes and decompression experiments. Microstructural data include spherical vesicles and jigsaw-puzzle association of broken crystals in pumices, whereas there is limited breakage of crystals in lavas. These observations insinuate that shearing of magma during ascent was limited. Decompression experiments reveal contrasting interaction between growing gas bubbles and the crystal framework in crystal-rich magma. Under slow decompression typical of effusive eruptions, gas extraction is promoted, whereas under rapid decompression, bubbles are retained and the crystal framework collapses. This feedback between decompression rate, retention of gas bubbles, and integrity of the crystal framework leads to strong non-linearity between magma decompression rate and eruption explosivity. We extend these findings to caldera-forming eruptions of crystal-rich magma where large overpressures are induced by caldera-collapse, resulting in magma plug-flow, rapid decompression facilitated by shear-localization at conduit margins, and explosive eruption.

Influence of hydrolysis behaviour and microfluidisation on the functionality and structural properties of collagen hydrolysates.

The functionality and structural properties of pig skin hydrolysates with different degrees of hydrolysis (DH, 10% and 20%) and microfluidisation (120MPa), prepared by pepsin and Alcalase® have been investigated in this study. Extensive hydrolysis can significantly improve the absolute value of the zeta potential and surface hydrophobicity. The particle distribution of hydrolysates decreased with increasing DH. The numbers of free sulfhydryl (SH) and disulfide bonds (SS) were significantly increased with increasing DH (p<0.05). Hydrolysates with a lower DH showed a better emulsifying property than those with a higher DH. Microfluidisation led to the transformation of structural and interfacial properties of the hydrolysates and increased the value of the zeta potential, S0, and gel strength. Microfluidisation results in limited breakage of chemical bonds, the number of SS and SH bonds unchanged in the treatment. These results reflect the functionality and structural properties of collagen-rich pig skin hydrolysates.

Microstructure and mechanical properties of milled fibre/SiC multilayer composites prepared by tape casting and pressureless sintering

In the present work, milled carbon fibre with high mechanical properties was used to reinforce silicon carbide, and Csf/SiC multilayer composites were prepared by tape casting and pressureless sintering. The milled C fibres were firstly dispersed in solvents with the aid of dispersant (Triton X-100) and then mixed with SiC slurry to make green Csf/SiC tapes to limit fibre breakage. The average length of C fibres slightly decreased with the increase of mixing time in the present duration, indicating that mixing the SiC slurry with the fibre-predispersed solution is an effective method for adding fibres with limited breakage. Fibres were homogeneously distributed in the tapes and tended to align fairly well along the tape casting direction. The relative density of the composite containing milled C fibres decreased with the fibre amount. The Csf/SiC multilayer composites demonstrated significant anisotropic shrinkage behaviour in different directions, while the addition of short C fibres hindered the shrinkage in the plane containing the fibres during sintering. Elastic modulus and bending strength decreased with increased porosity, which implies that bending properties are affected more significantly by residual porosity rather than fibres' properties.

Uniaxial compression of dense granular materials: Stress distribution and permeability

A uniaxial compression apparatus designed to investigate the dynamics of proppant particle packing is described. This dynamic compression device (DCD) uses a small charge of particles, approximately 3.5–7 cm 3 depending upon the configuration of an experiment. The DCD allows simultaneous measurement of boundary stresses on the packing and permeability of the packing to fluid flow. Visualization of the packing at compressive stress levels up to σ A = 7100 psi (49 MPa) is also demonstrated. The stresses measured are the normal stress at both walls on the axis of compression, with their difference providing a measure of the shear (or friction) force from the walls, and the transverse normal stress on one orthogonal axis, σ T . Permeability may be determined by either a fixed pressure drop or fixed flow rate experiment, with results presented from the fixed pressure drop approach by imposing a small gravity head of the flowing liquid; liquid flow is gravimetrically measured. The behaviors of packings of hard particles, both uncoated and when coated with a very viscous and tacky polyamide resin, are reported. The packing materials include a ceramic material used as a proppant in hydraulic fracturing of petroleum wells, and glass beads. The proppant and glass beads have mean diameters of approximately 700 μm and 500 μm, respectively, with the proppant less spherical and more polydisperse than the glass beads. The proppant particles undergo only limited breakage up to the maximum stress imposed here. The glass beads undergo significant breakage. Protocols for the compression can be varied. The reported results use a single loading and unloading at the same speed in each segment (increasing and decreasing stress), as well as a cyclic loading of differing numbers of cycles. The rate of loading is specified and can be varied from 0.56 μm/s–1.7 mm/s, with results here focusing on the range of 1–30 μm/s. Measured stress and permeability are shown as a function of axial load and loading rate, as well as the behavior in cyclic loading. The results are shown to be highly reproducible, establishing the ability to determine the properties of a proppant pack in a small charge device with imposed deformation. The influence of the resin coating on the properties is reported. Direct visualization is one of the key features of the DCD. Local motions and overall rearrangements of particles can be monitored by digital camera. These have been presented using particle image velocimetry (PIV).

Theoretical analysis of the steady state particle size distribution in limited breakage processes

The steady state particle size distribution is examined, resulting from a breakage process with a maximum stable size and a homogeneous continuous kernel. The dynamic breakage problem is transformed into one that allows direct solutions for the steady state distribution. The latter depends on the breakage kernel and on the ratio of critical to initial size. As this ratio goes to zero the steady state distribution approaches its limiting form obtained by the authors previously [7]. A general theoretical analysis concerning the steady state distribution is presented herein. The asymptotic behaviour is determined with regard to various limits. Perturbation analysis for nearly uniform kernels reveals several interesting features of the problem. For the general continuous kernel, the problem can be cast in a matrix form amenable to a conventional theoretical treatment. Finally, comparisons of the new results with existing solutions of the dynamic problem, for large times, confirm their validity.

An explicit relationship between steady-state size distribution and breakage kernel for limited breakage processes

The steady-state particle-size distribution is examined, resulting from a breakage process with a maximum stable size. If the latter is much smaller than the characteristic size of the initial distribution, the steady-state distribution for continuous breakage kernels is independent of the breakage frequency and of initial conditions and is shown to be a simple function of the breakage kernel. For discontinuous kernels, the steady-state size distribution is always dependent on the initial conditions.

Fragmentation of small coal particles under fluidized-bed combustor conditions

Particles of four coals sereened to mean diameters (do) of 1.5 and 2.5 mm were subjected to rapid radiant heating under nitrogen and/or 5% oxygen, and the product particles were collected after some seconds. The number distributions of size for the products were compared to the original distributions. The 1.5-mm particles suffered limited breakage with some dust and a small amount of do/2 fragments produced. The amount of breakage was independent of volatile matter content, but greater with higher vitrinite materials. The behavior was consistent with the predictions of a model based on thermally induced stress. The manner of breakage of 2.5-mm particles of a very high VM coal and an anthracite were contradictory, with only some particles of the former breaking, but most of the latter. Increasing the pressure to 1.0 MPa led to less breakage with the high VM coal, suggesting that pressure from the volatiles is contributing to breakage. The degree of fragmentation under 1.0 MPa increased for the anthracite, which is consistent with the operation of the thermal stress model. The influence of oxygen on breakage in this case is determined by the volatile matter content.

Light response inPhycomyces blakesleeanus: Evidence for roles of chitin biosynthesis and breakdown

Chitin synthetase activity, both basal and zymogenic, fromPhycomyces sporangiophores was stimulated by lightin vitro andin vivo. AmadB mutant did not display these activations, whereas in amadE mutant only chitin synthetase zymogen was increased by illuminationin vivo. Light also produced a transient alteration in cell wall structure at the apical region of the sporangiophore revealed by accessibility of chitin to binding by wheat germ agglutinin and by an increased limited breakage of chitin microfibrils. This last response was absent in bothmadB andmadE mutants. Accordingly, it is suggested that the light growth response in the sporangiophore fromPhycomyces is due to a transient softening of the cell wall at the growing region followed by an elongation due to the turgor pressure of the cell and an enhanced chitin biosynthesis by the apically localized chitin synthetase which restores normal strength to the cell wall. A hypothetical scheme to account for these results is presented.

Effects of lysozyme on Bacillus cereus 569: rupture of chains of bacteria and enhancement of sensitivity to autolysins.

Bacillus cereus 569 is known to be resistant to lysis by lysozyme because of the presence of deacetylated glucosamine residues in its peptidoglycan, and cultures continued to grow even in the presence of lysozyme at 200 microgram ml-1. However, lysozyme caused rupture of the chains of bacteria and promoted the rate of autolysis in a non-growing cell suspension, causing a doubling of the rate of release of radioactively labelled wall material. Heat-inactivated cells did not autolyse and were not lysed by lysozyme unless they were supplemented by unheated cells or cell-free autolysate. Enhancement of autolysin activity could also be effected by pre-treatment of heated cells with lysozyme. The action of lysozyme on isolated cell walls released some free reducing groups, indicating limited breakage of the polysaccharide chains of peptidoglycan, and it was concluded that lysozyme modified the peptidoglycan and made it more susceptible to autolysin(s). Lysozyme also enhanced the rate of septum separation and the probable significance of the results in relation to the control of cell separation is discussed.

The relationship between DNA strand-scission and DNA synthesis inhibition in HeLa cells treated with neocarzinostatin

Neocarzinostatin inhibits DNA synthesis in HeLa S 3 cells and induces the rapid limited breakage of cellular DNA. The fragmentation of cellular DNA appears to precede the inhibition of DNA synthesis. Cells treated with drug at 37°C for 10 min and then washed free of drug show similar levels of inhibition of DNA synthesis or cell growth, or of strand-scission of DNA as when cells were not washed. If cells are preincubated with neocarzinostatin at 0°C before washing, the subsequent incubation at 37°C results in no inhibition of DNA synthesis or cell growth, or cutting of DNA. Isolated nuclei or cell lysates derived from neocarzinostatin-treated HeLa S 3 cells are inhibited in DNA synthesis but this can be overcome in cell lysates by adding activated DNA. A cytoplasmic fraction from drug-treated cells can stimulate DNA synthesis by nuclei isolated from untreated cells, whereas nuclei from drug-treated cells are not stimulated by the cytoplasmic fraction from untreated cells. By contrast, neocarzinostatin does not inhibit DNA synthesis when incubated with isolated nuclei, but it can be shown that under these conditions the DNA is already degraded and is not further fragmented by the drug. These data suggest that the drug's ability to induce breakage of cellular DNA in HeLa S 3 cells is an essential aspect of its inhibition of DNA replication and may be responsible for the cytotoxic and growth-inhibiting actions of neocarzinostatin.