Properties of Commercial Kraft Paper Honeycomb Furniture Stock Panels Conditioned under 65 and 95 Percent Relative Humidity

Abstract

Physical and mechanical properties of a range of commercially produced kraft paper honeycomb stock panels were assessed to provide technical information of interest to primary and secondary manufacturers and product end users. Five groups of four replicate panels each 44.45 mm in thickness were fabricated by Panolite Industries, Lac Megantic, Quebec, from unlaminated 6.3- and 9.5-mm-thick medium-density fiberboard (MDF) and particleboard (PB), and 3.2-mm-thick veneered hardboard (HB). At 65 percent relative humidity (RH) sandwiches made from MDF were superior in mechanical properties to those made from PB. Marked differences in flexural properties were found for 3.2-mm veneered HB; this type of facing and the sandwich structure made from it is significantly greater in flexure when the wood veneer runs parallel to the long axis of the panel. For PB and MDF facings, sandwiches were stronger and stiffer if made from thicker facing material (9.5 mm), and there was a small but significant effect of honeycomb ribbon orientation: an orientation parallel to the long axis of the panel/test specimen gives the sandwich greater resistance to deformation under load. Conditioning facing materials and sandwich specimens under 95 percent RH over 45 days caused loss of strength properties of up to 50 percent, especially for 6.3-mm MDF.

Shear mechanical properties of the core structure of biomimetic fully integrated honeycomb plates

“…Honeycomb plate is one kind of lightweight and high-strength structures [1–3], which was first used in the aerospace industry [4]. Nowadays, honeycomb plates are commonly applied in many fields not only for building walls, such as curtain walls [5,6] and external insulation walls [7–10], but also in foundation slabs and seismic reduction devices [11–13]. They can also be used to fabricate high-speed machine worktables [14].…”

Investigating the effects aviation fluids have on the flatwise compressive strength of Nomex® honeycomb core material

“…The use of composite sandwich structures has increased significantly. The main application of composite sandwich structure is in the aerospace industry because a high stiffness-to-weight ratio of a structure is one of the most critical factors during the aircraft design process [1][2][3][4][5][6][7]. An aircraft design requires the aircraft structure to resist various kinds of loads that are applied to the aircraft structure.…”

“…For this reason, composite sandwich structure is used not only in primary structure of the aircraft, such as wings, fuselage, flaps, rudder, and fairings, but also for engine cowls, nacelles, radomes, floors, doors, and overhead storage bins [1,2,[9][10][11]. Besides the high strength-to-weight ratio, composite sandwich structure has many other advantages, such as corrosion resistance, design flexibility, fatigue resistance, and high temperature resistance [1,3,4,9,12]. Because of these advantages, traditional materials such as aluminum and steel have been replaced by composite materials.…”

“…Wang et al [20] reported that a higher moisture content decreases the critical stress and plateau stress of the honeycomb during compressive test with paper honeycomb. Semple et al [4] showed that paper honeycomb losses its flexural stiffness, shear strength, and compressive strength significantly in high humidity (95% RH) compared to normal humidity (65% RH). Allred and Roylance [22] and Yin et al [23] reported that degradation of mechanical property of Nomex V R honeycomb core is caused by water molecules which destroy hydrogen bond network of the aramid fiber.…”

“…where F z fcu is the ultimate flatwise compressive strength, P max is ultimate failure load, and A is cross sectional area of the structure that is calculated to 31.75 mm × 31.75 mm = 1008.0625 mm 2 . To calculate the compressive modulus of the specimen, stress and strain were calculated using collected data using following equations; (4) where σ is stress, and P is applied compressive load. ε is strain, ∆L is thickness change during compressive test, and L 2 is original thickness of specimen.…”