Effect of in-Plane Shear Modulus of Elasticity on Buckling Strength of Paperboard Plates

In previous research, a thin-plate theory was derived for analyzing corrugated fiberboard under edgewise compression and subjected to localized buckling. In this note, buckling formulas for thin paperboard plates characterized by an approximate in-plane shear modulus of elasticity are further generalized to allow for arbitrary levels of shear modulus. The results have applications in the design of paper products made of composite plates

Discovery of a tidal dwarf galaxy in the Leo Triplet

We report discovery of a dwarf galaxy in the Leo Triplet. Analysis of the neutral hydrogen distribution shows that it rotates independently of the tidal tail of NGC 3628, with a radial velocity gradient of 35-40 km s$^{-1}$ over approximately 13 kpc. The galaxy has a very high neutral gas content, explaining large part of its total dynamic mass - suggesting small dark matter content. As it is located at the tip of the gaseous tail, this strongly suggests its tidal origin. Should it be the case, it would be one of the most confident and closest (to the Milky Way) detections of a tidal dwarf galaxy and, at the same time, a most detached from its parent galaxy ($\approx$140 kpc) object of this type.Comment: 6 pages, 4 figures; The Astrophysical Journal, in pres

A search for extended radio emission from selected compact galaxy groups

Context. Studies on compact galaxy groups have led to the conclusion that a plenitude of phenomena take place in between galaxies that form them. However, radio data on these objects are extremely scarce and not much is known concerning the existence and role of the magnetic field in intergalactic space. Aims. We aim to study a small sample of galaxy groups that look promising as possible sources of intergalactic magnetic fields; for example data from radio surveys suggest that most of the radio emission is due to extended, diffuse structures in and out of the galaxies. Methods. We used the Effelsberg 100 m radio telescope at 4.85 GHz and NRAO VLA Sky Survey (NVSS) data at 1.40 GHz. After subtraction of compact sources we analysed the maps searching for diffuse, intergalactic radio emission. Spectral index and magnetic field properties were derived. Results. Intergalactic magnetic fields exist in groups HCG 15 and HCG 60, whereas there are no signs of them in HCG 68. There are also hints of an intergalactic bridge in HCG 44 at 4.85 GHz. Conclusions. Intergalactic magnetic fields exist in galaxy groups and their energy density may be comparable to the thermal (X-ray) density, suggesting an important role of the magnetic field in the intra-group medium, wherever it is detected.Comment: 13 pages, 4 figures, 3 tables, accepted for publication in A&

Box Compression Analysis of World-Wide Data Spanning 46 Years

The state of the art among most industry citations of box compression estimation is the equation by McKee developed in 1963. Because of limitations in computing tools at the time the McKee equation was developed, the equation is a simplification, with many constraints, of a more general relationship. By applying the results of sophisticated finite element modeling, in this current study we derive a more general box compression formula that preserves the underlying theory of the McKee equation but removes the constraints. This formula is solvable with modern spreadsheet software, and we present an implementation method and example outputs as we relax or impose the various constraints. We analyze data obtained from multiple literature sources containing the traditional McKee equation inputs. We quantify the disparity between the McKee equation and the various sources of data and present an improved model for single-wall box-compression strength. The model attaches physical meaning to what were previously only fitting parameters, and it can serve as a tool for additional explorations in box optimization

Finite Element Corroboration of Buckling Phenomena Observed in Corrugated Boxes1

Conventional compression strength formulas for corrugated fiberboard boxes are limited to geometry and material that produce an elastic postbuckling failure.Inelastic postbuckling can occur in squatty boxes and trays, but a mechanistic rationale for unifying observed strength data is lacking. This study combines a finite element model with a parametric design of the geometry and material characteristics affecting the critical buckling stress of box panels to examine their postbuckling response. The finite element model enables a broad scope of simulated panels to be examined economically. Results lead to a postbuckling model fit to the predictions and a better understanding of how to unify elastic and inelastic failure data from actual experiments and form a more general box strength formula

Swept Sine Humidity Schedule for Testing Cycle Period Effects on Creep

The stacking life of corrugated containers under load decreases as relative humidity (RH) increases and when RH cycles, compared with when RH remains stable. Conventional RH test schedules that rely on fixed cycle periods do not adequately reflect the significance of moisture diffusion and hygroexpansion rate phenomena on the creep of corrugated containers and general wood fiber products. With cycle periods shorter than a critical period, materials are relatively unaffected by cyclic changes in RH. Longer periods amplify material hygroexpansion and accelerate creep. In this study, we propose a swept sine RH schedule in which the cycle frequency varies logarithmically with time and set forth equations for generating a numerical control signal. Data from creep tests of corrugated fiberboard reveal the frequency dependence of the amplitude and phase relationships between cyclic hygroexpansion and cyclic RH. A swept sine RH schedule yielded the continuous form of the response characteristics varying with cycle period that could not be acquired with multiple constant period schedules. The critical cycle period and the hygroexpansion response to moisture as a function of cycle period are proposed as criteria for discriminating among hygroexpansion-creep models

Buckling of Axially Loaded, Long Rectangular Paperboard Plates

This study examines the elastic buckling of long rectangular plates made of paper and subjected to compressive axial loading. The model is appropriate for the facing and flute components of corrugated fiberboard. A dimensionless stiffness, S, and mean Poisson's ratio, v, characterize the dimensions of the plate and the nonlinear orthotropic stress-strain relation of paper. The dimensionless buckling stress σ depends on S, v, and the plate edge condition, which can be fixed or simply supported. An examination of σ versus S predicts the stiffness needed to prevent elastic buckling and shows how the significance of edge restraint and material nonlinearity vary with S. An iterative solution is given for doing the analysis. Comparing the results obtained assuming fixed edges to those obtained assuming simply supported edges explains how fiberboard strength may vary due to component variations. Comparing the results obtained for nonlinear materials to those obtained for linear materials explains why fiberboard edgewise compressive strength cannot be accurately predicted from only the components' strengths