Zhongwei Guan

University of Liverpool | UoL ·  Centre for Materials & Structures

This paper investigates five groups of compressed wood (CF), four of them made from compressed Japanese cedar with four different compression ratios (CR) of 33%, 50%, 67% and 70% and one without compression (control). The specimens were conditioned in relative humidity (RH) of 60% with moisture content (MC) of 12%. Mechanical properties tested were...

A Nomex honeycomb core has been reinforced with small diameter composite rods and tubes in order to enhance its compression properties and energy-absorbing characteristics. The influence of the areal density of the rods and tubes on the strength and energy-absorbing properties of the reinforced honeycomb was investigated by introducing increasing n...

The behaviour of concrete filled steel tube (CFST) columns has been investigated intensively against lateral and axial impact loading. However, there is a lack of knowledge on the impact response of the connection between such the column and steel beam. In order to close this gap, the most common connections with a partial depth end plate (PDEPCs),...

The behaviour of different steel beam to column connections has been studied intensively against static and seismic loading regimes. However, there is a lack of knowledge on the response of such connections against impact and blast. In order to close this gap, the most common connections with partially depth end plate (PDEPCs), as a simple connecti...

This paper presents the study on structural behaviour of glulam beams pre-stressed by compressed wood (CW) in terms of load carrying capacity, strength and stiffness. Glulam beams were strengthened by inserting CW blocks into the pre-cut rectangular holes on the top of the beams. This practice was to make use of moisture-dependent swelling nature o...

Finite element modelling has been applied to simulate various failure modes in fibre metal laminate (FML) panels under localized high intensity blast loading. A relatively simple material model, based on continuum damage mechanics, has been proposed to describe the constitutive response of the composite material in the FMLs. Simulations of the blas...

The low velocity impact response of composite materials manufactured from dry fibre tows using the automated fibre placement technique has been investigated. Following fibre placement, the dry preforms were infused with an epoxy resin. The influence of incorporating graphene oxide (GO) nanoparticles into the matrix was investigated, and the impact...

The rate-sensitivity of a range of fibre metal laminates (FMLs) has been investigated though split Hopkinson bar, quasi-static perforation and low velocity impact tests. Initial attention focused on assessing the rate-sensitivity of the constituent materials, that is the glass fibre reinforced epoxy and the three aluminium alloys. This was followed...

This article presents a method to predict and assess the interaction between a human body and a spring mattress. A three-layer artificial neural network model was developed to simulate and predict an indentation curve of human spine, characterized with the depth of lumbar lordosis and four inclination angles: cervicothoracic, thoracolumbar, lumbosa...

This paper investigates the compression properties of square and triangular honeycomb core materials based on co-mingled flax fibre reinforced polypropylene (PP) and polylactide (PLA) polymers. Initial testing focused on investigating the sensitivity of the tensile properties of the composites to variations in processing conditions. Following this,...

A new approach to reinforce glulam timber beams has been developed by using compressed wood (CW) which is made of a lower grade wood through densification processes. In the reinforcing practice, compressed wood blocks are inserted into pre-cut holes on the top of glulam beams to produce pre-camber and to generate initial tensile and compressive str...

This paper describes the findings of a combined experimental/numerical study on the perforation resistance of sandwich structures. The impact response of sandwich panels based on PVC foam cores has been evaluated by determining the energy to perforate the panels. The dynamic response of the sandwich structures was predicted using the finite element...

This article describes the low velocity impact response of sandwich structures based on layered cores fabricated by bonding foams with different densities and carbon fiber skins together, investigated both experimentally and numerically. The impact behaviour of the panels was characterized by recording the resulted load-displacement traces and by d...

This article examines the crushing characteristics behavior of fiber rod reinforced PVC foam cores for lightweight sandwich structures for potential impact resistant applications. Crush tests have been undertaken on a series of cross-linked PVC cores with densities from 40 to 200 kg/m3 reinforced by various fiber rods in diameters of 2, 3 and 4 mm....

This paper presents experimental study of the fatigue and static behavior of reinforced concrete (RC) beams locally reinforced by fibre reinforced polymer (FRP). In this study, five rectangular RC beams with different reinforcing and loading arrangements were constructed and tested, i.e., one reference beam with FRP reinforcement statically loaded...

A parametric study has been undertaken in order to investigate the influence of the properties of the aluminium alloy on the blast response of fibre-metal laminates (FMLs). The finite element (FE) models have been developed and validated using experi-mental data from tests on FMLs based on a 2024-O aluminium alloy and a woven glass-fibre/polypropyl...

The effect of through-the-thickness stitching on the blast resistance of sandwich panels is investigated both experimentally and numerically. Panels based on three-dimensional woven S-glass/epoxy skins and a crosslinked PVC core were manufactured using a vacuum assisted resin infusion process. The panels were stitch-bonded using Kevlar 129 yarn, by...

This paper investigates the influence of varying core density on the blast resistance of sandwich panels based on crosslinked PVC cores and aluminium alloy skins. Initially, the findings of a series of compression and single edge notch bend and shear tests are presented in order to characterise the strength and toughness characteristics of the foam...

In this study, glulam beams were strengthened by inserting compressed wood (CW) blocks into the pre-cut rectangular holes with one-thirds of the beam depth from the top of the beams. This practice was to make use of moisture-dependent swelling nature of the compressed wood which was conditioned with the moisture content significantly lower than the...

The impact behaviour of sandwich structures made with glass resin plastic (GRP) face sheets and polyvinyl chloride (PVC) foam cores has been simulated using three dimensional (3D) nonlinear finite element (FE) models to investigate the influence of core properties on the low velocity impact perforation resistance of sandwich structures based on a w...

In this article, experimental results are presented investigating the response of glass fiber composites subjected to low velocity impact loading. The resulting load-displacement traces and deformation modes have been used to validate a number of numerical models. Here, finite element models have been developed to predict the impact behavior of the...

Based on the use of carbon fibre reinforced polymer (CFRP) and the technique of externally bonded reinforcement strengthening arrangement to flexural strengthen of reinforced concrete (RC) beams. A total of 7 RC beams with different cross section depth, the longitudinal reinforcement ratio, the pre-crack width and the concrete cover thickness were...

Lattice structures based on two simple architectures have been manufactured from 316L stainless steel using the selective laser melting process. The compressive properties of structures based on a body-centered cubic (BCC) and a similar structure with vertical pillars (BCC-Z) were initially investigated at quasi-static rates of strain. Blast tests...

Structural impact tests were first presented to cover typical fibre metal laminates (FMLs) subjected a low velocity projectile impact, which produced the corresponding load-displacement traces and deformation/failure modes for the validation of numerical models. Finite element (FE) models were then developed to simulate the impact behaviour of FMLs...

In this research, five groups of compressed wood specimens were investigated, four made from compressed Japanese cedar (Cryptomeria japonica D. Don) with compression ratios (CR) of 33%, 50%, 67% and 70%, and one without compressing for control purpose. The measurements of moisture-dependent swelling of the specimens were carried out in the R, T and...

Brittle premature failure caused by splitting parallel to the timber grain is a common failure mode in glulam joints made with solid dowel type fasteners. It is thought that this problem can be alleviated by using hollow steel dowels as the fasteners and reinforcing the timber locally in the area of the joint. In this way, by varying the wall thick...

In this study, five groups of specimens were investigated, four made from compressed Japanese cedar with 4 different of compression ratios (CR) of 33%, 50%, 67%, and 70% and one without compressing for controlling purpose. The specimens for mechanical property were conditioned in Relative Humidity (RH) of 60% with a target MC of 12%. Mechanical pro...

A new approach to reinforce glulam timber beams has been developed by using compressed wood (CW) which is made of a lower grade wood through densification processes. In the reinforcing practice, compressed wood blocks are inserted into pre-cut holes on the top of glulam beams to produce pre-camber and to generate initial tensile and compressive str...

In this paper, finite element models were developed to simulate fibre metal laminates subjected to various blast loadings with typical pressure-time patterns. The aluminium (alloy grade 2024-0) layer was modelled as an isotropic elasto-plastic material up to the on-set of post failure stage, followed by shear failure and tensile failure to simulate...

This paper presents the study on structural behaviour of glue-laminated (glulam) timber beams reinforced by compressed wood (CW) in terms of load carrying capacity, strength and stiffness. Glulam beams were strengthened by inserting CW blocks into the pre-cut rectangular holes on the top of the beams. This practice was to make use of moisture-depen...

Steel dowels and plates are widely used in modern timber joints, which are difficult to be recycled. Also due to large difference on stiffness between the steel and the timber, there is a poor compatibility in the joint that produces less integrity. Therefore, a desired joint should be made with non-metallic fasteners, ideally timber fasteners. In...

This paper outlines the use of finite element analysis to describe the heat transfer in footwear. Experiments were conducted to determine the temperature distribution in footwear with a variety of environmental temperature and footwear properties considered. Finite element models describing the heat transfer between the foot, sock and shoe are pres...

This article models the impact response of fiber–metal laminates (FMLs) based on a polypropylene (PP) fiber/PP matrix composite and two types of aluminum alloy. Here, a finite element analysis is used to model the impact behavior of FMLs at velocities up to 150 m/s. The PP-based composite was modeled as an isotropic material with a specified tensil...

In this paper, constitutive equations to model anisotropic elasto-plastic timber composite beams with openings were formulated and implemented into the finite element (FE) package ABAQUS, via a user-defined subroutine. The Tsai–Hill criterion was applied to judge failure of Oriented Strand Board (OSB) and timber in tension. Both OSB and timber in t...

Fibre Metal Laminate structures (FMLs) consist of thin layers of metal sheet and unidirectional fibre layers embedded in an adhesive system. They have superior material properties to resist impact loading and fatigue, in addition to the very low weight to strength ratio. Apart from the thin metal layer, the fibre layer can also be modified and repl...

A new completely analytical integral algorithm is proposed and applied to the evaluation of nearly singular integrals in boundary element method (BEM) for two-dimensional anisotropic potential problems. The boundary layer effect and thin body effect are dealt with. The completely analytical integral formulas are suitable for the linear and non-isop...

Initial conditions introduced by different wedges in a traditional Japanese “Nuki” joint affect its stiffness and load carrying capacity significantly. Due to the complicated nature of the problem, no proper measurements have been undertaken historically, nor has there been theoretical modeling of the initial stress state in the joint. This leads t...

The “Nuki” joint is a common timber connection in Japan, not only for historic buildings, but also for modern domestic houses. Its racking performance is dependent upon a number of factors, such as dimensions of the column and the beam, material properties of the joint members, and wedge configurations, etc. Among them, the wedge configuration, whi...

Modelling of timber failure is always a challenging task due to its brittle failure nature accompanying by fast crack growth. In this paper, using the explicit algorithm 3-D finite element models were developed to simulate post failure mechanism of timber fasteners with various local reinforcement, such as bamboo-plywood and carbon fibre. However,...

There exist nearly singular integrals for boundary layer effect problem and thin body effect problem in the boundary element method (BEM). A new completely analytical integral algorithm is proposed and applied to evaluate the nearly singular integrals in the BEM for two-dimensional orthotropic potential problems of thin bodies. The completely analy...

This paper presents the research on thermal/moisture mapping of typical industrial safety helmets using match-head-sized sensors. Three types of the industrial safety helmet were tested, one without ventilation openings, one with small ventilation holes made by the researcher, and one with manufacturing ventilation openings in the top region. Up to...

Tests conducted on oriented strand board (OSB) webbed wood I-joists with web openings revealed that the typical failure mode was that the OSB fractured from tension zones around an opening, with cracks developing diagonally toward the joist flanges. The joist collapsed when the cracks reached the flanges. Finite-element models were developed using...

Embedding strength is a key parameter most commonly adopted for designing laterally loaded timber joints fastened with dowel-type fasteners. This property, however, is non-unique for any given specimen of timber but is dependent upon several factors. Currently, there is a scarcity of literature that considers some of the major factors as a whole. I...

Experiments were conducted on beams with openings spaced at different intervals along the web. It was observed that the OSB fractured from tension zones around an opening, with cracks developing diagonally towards the beam flanges. A beam would collapse when the cracks reached the flanges. Interactions between openings further reduced the load carr...

Improvement of the load carrying capacity of glulam beams by the addition of reinforcement is now common practice. Recently it has been demonstrated that pre-stressing of beams using pultruded glass fibre reinforced plastic (GRP) tendons provides an available alternative due to the compatibility of the two materials and the low losses of pre-stress...

Experimental work was conducted on oriented strand board webbed wood I-joists to investigate the buckling behavior. Both lateral buckling and local web buckling were witnessed in the tests. The two types of buckling were reproduced in the finite element simulations using ABAQUS. The buckling modes and usually overestimated buckling loads of a joist...

Experiments were conducted to determine some of the material properties of OSB. Tests covered three in-plane board directions and the through thickness direction. Results showed that OSB is an orthotropic material with better material properties in the direction of strand orientation. OSB in tension behaves almost linearly up to failure, whilst in...

Openings are necessary in oriented strand board webbed wood I-joists to allow electrical wires/service pipes pass through their webs. Sizes and locations of the opening are variable, which could be crucial in some circumstances. There is a high possibility that crack will grow in high stress/strain areas, especially in tension corners of large size...

Joints are a matter of crucial importance in any major timber structure. They must have satisfactory strength and stiffness together with reasonable ductility and energy absorption, particularly if designed for use in seismic areas. In joints made with dowels, these requirements may more easily be met if the timber is reinforced locally in the area...

Dowel type fasteners used in timber joints are traditionally of solid cross section. The rigidity of those with a larger diameter increases the chances of brittle failure in the timber components. Hollow fasteners of variable wall thickness, whilst maintaining the required timber performance, offer variable fastener rigidity and the likelihood of e...