۱- Introduction

۲- Experimental methods

۳- Experimental results

۴- Analytical analysis

۵- Finite element analysis

۶- Application in residential stud walls

۷- Conclusions

References

Abstract

Increasing awareness of environmental concerns is leading a drive towards more sustainable structural materials for the built environment. Natural fibres such as flax and jute have increasingly been considered for fibre-resin composites, with a major motivation for their implementation being their notable sustainability attributes. This paper is part of an ongoing effort by the author to demonstrate the structural properties of primary structural elements and members fabricated from natural fibre composites of flax and jute. Previously the structural properties of flat plates, plain channel sections and channel sections with complex stiffeners were investigated under pure compression. This paper presents investigations of channel sections with complex stiffeners under pure bending. A series of sixteen channels with varying geometries, complex stiffener arrangements and composite thicknesses were tested in pure flexure. Material tests indicated that the mean tensile elastic stiffness and strength values were 6386 MPa and 55.1 MPa for flax, and 6941 MPa and 62.1 MPa for jute. The experimental results indicated that flexural failure of the channel sections was governed by tensile fracturing. The ultimate moment capacities varied from 1.043 to 1.501 kNm for four-layered composites, and 2.184 to 2.511 kNm for six-layered composites. The analytical models predicted the experimental ultimate moment capacities well, with a mean and coefficient of variation of the test to predicted ratio of 0.97 and 0.06, respectively. Finite element models used progressive damage analysis via stress-based damage initiation models and damage evolution laws, to replicate the tension fracture failure mode of the channels. The numerical models predicted the experimental ultimate moment capacities well, with a mean and coefficient of variation of the test to predicted ratio of 0.99 and 0.06, respectively.

Introduction

Public concerns about the environment, climate change, energy consumption and greenhouse gas emissions are driving demand for the use of sustainable materials in the built environment. There has been substantial attention given to the use of natural fibres in fibre-reinforced plastics in recent decades, where such fibres may be combined with thermoset or thermoplastic polymers to create natural fibre composites. Such natural fibre composites have particularly been identified for their favourable sustainability properties, including for example: renewable resource; carbon sink; short growth cycle time; low herbicide requirements due to rapid growth; low energy production; recyclable; biodegradable; and low hazard manufacturing and composite handling and working [1-7]. Much of this research has been from a materials science standpoint, assessing materials aspects such as fibre processing techniques, composite fabrication methodologies, matrix materials and their effects on the mechanical properties [8-13]. This research has indicated that composites consisting of natural fibres have general characteristics similar to their synthetic fibre counterparts, such as glass and carbon, however have comparably low intrinsic mechanical properties [2-13]. As a result, identifying structural applications such as those in civil infrastructure have thus far been limited [14-22].