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Publications (148)
The mussel thread-plaque system exhibits strong adhesion and high deformability, allowing it to adhere to various surfaces. While the microstructure of plaques has been thoroughly studied, the effect of their unique porous structure on the high deformability remains unclear. This study first investigated the porous structure of mussel plaque cores...
A novel damage evolution model for unidirectional (UD) composites is established in this paper in the context of continuum damage mechanics (CDM). It addresses matrix cracking and it is to be applied along with the damage representation established previously. The concept of damage driving force is employed based on the Helmholtz free energy. It is...
The Hashin criterion is one the most popular failure criteria for fibre reinforce composites. It is critically appraised in this paper. The most significant feature of the criterion is failure modes introduced and the assumption that failure is determined by the traction on the failure plane. For this assumption, there has never been any justificat...
The high deformability and multi-scale porous microstructure of the mussel plaque.
Weft tows in 3D woven composites are commonly approximated as perfectly straight, but their undulations are inevitable in reality, although the extent of undulations in the weft tows is not as pronounced as in the warp tows. Such minor undulations in weft tows have been simulated in this paper. A previously established parametrised modelling and an...
The mussel thread-plaque system exhibits strong adhesion and high ductility, allowing it to adhere to various surfaces. While the microstructure of plaques has been thoroughly studied, the effect of their unique porous structure on ductility remains unclear. This study firstly investigated the porous structure of mussel plaque cores using scanning...
Existing failure criteria for orthotropic materials are subject to an underlying assumption which cause contradictions when applied to genuinely orthotropic materials that are significantly anisotropic in elasticity as well as in strengths. For such materials, there is lack of consistent failure criteria to support their applications in engineering...
A semi-analytical solution is obtained in this paper for the micromechanical analysis of the square and hexagonal unit cells using complex potentials. It provides a means of numerical characterisation of unidirectionally fibre-reinforced composites for their effective properties. This process is considered as the forward problem and its inverse cou...
A novel stress analysis method is developed for the efficient design of radially laminated annular beams/shafts subject to arbitrary load combinations. The analysis is conducted using classic laminate theory (CLT) in conjunction with a mechanics of materials (MoM) approach based on the plane section assumption. Global loads are related to the globa...
A theoretical framework that underlies an accelerated testing method for unidirectional (UD) composites is proposed in this article, based on the continuum damage mechanics and time–temperature superposition. By the way of demonstration, it has been applied to problems involving constant strain rates and fatigue loading conditions. The damage evolu...
The comprehensive design feasibility for woven composites has been established by identifying the missing component in the design tool for these materials, the so-called controllable parameters. These are the parameters that are involved, directly or indirectly, in manufacturing of woven preforms, and they include the tow densities, the number and...
By examining the quadratic function of the original Tsai-Wu failure criterion for transversely isotropic materials from the perspective of analytic geometry, two of the troublesome coefficients associated with the interactive terms, one describing interaction between in-plane direct stresses and one between transverse direct stresses, can be determ...
The unsprung masses associated with the axles of a railway vehicle result in costly impact damage to the rail infrastructure. A hybrid metallic-composite (HMC) railway axle is evaluated using finite element analysis. The axle mass is 74 kg, 63% lighter than an equivalent hollow steel axle. The HMC railway axle comprises a full length, carbon fibre...
The quadratic function of the original Tsai–Wu failure criterion for transversely isotropic materials is re-examined in this paper. According to analytic geometry, two of the troublesome coefficients associated with the interactive terms—one between in-plane direct stresses and one between transverse direct stresses—can be determined based on mathe...
Continuous Fibre composite 3D printing (CF-3DP) technology is a newly developed Additive Manufacturing (AM) process. By employing continuous fibre as a reinforcement for the composite, the mechanical properties of the 3D printed part can be significantly improved. However, owing to the process's early stage of development, the mechanical performanc...
In recent years, three-dimensional printing (3DP) technology has developed to include composite materials. Most of the development to date in this area has involved particulate or short fibre reinforced composites, whilst continuous fibre printing remains a relatively novel research area. This review paper focuses on the state-of-the-art of continu...
The paper presents experimental characterization and theoretical predictions of elastic and failure properties of continuous carbon fiber reinforced silicon carbide (C/C‐SiC) composite fabricated by Liquid Silicon Infiltration (LSI). Its mechanical properties were determined under uniaxial tensile, compression, and pure shear loads in two sets of p...
The nonlinear along-fibre shear stress–strain relationship for unidirectionally fibre-reinforced composites has been investigated in this paper aiming at its applications in general 3D stress conditions in a consistent manner. So far, such relationship has only been addressed in plane stress conditions. In this paper, it has been shown that its str...
The potential for lightweighting of railway axles was investigated to primarily reduce the unsprung mass of a rail vehicle. The reduction of unsprung mass equates to an overall lighter train which will help to reduce track damage, energy consumption and total operating costs. This work was performed within the NEXTGEAR project which is ascribed und...
The maximum strain failure criterion is unified with the maximum stress failure criterion, after exploring the implications of two considerations responsible for this: (1) the failure strains for the direct strain components employed in the maximum strain criterion are all defined under uniaxial stress states, not uniaxial strain states, and (2) th...
The Mohr failure criterion has been re-examined and re-presented in a rational manner in the context of brittle materials. The generic assumptions and their logical inferences have been elaborated, as well as the basic assumption of the isotropy of the material. It has been revealed for the first time that the assumption that ‘failure is determined...
In this paper, the method to unify the definition of woven architectures in textile composites over a wide range of variations has been established. This was achieved via parametrisation of the weaves, which was conducted employing a limited set of clearly defined parameters. Detailed description of these parameters has been given, based of which a...
The finite-element-implemented Koiter’s initial postbuckling analysis has not managed to convince commercial finite element code developers to incorporate it into their codes to benefit structural designers and analysts. Three key obstacles have been identified. With two of them being resolved recently, the present paper addressed the remaining one...
Numerical methods to estimate material properties usually involve analysis of a representative volume element (RVE) or unit cell (UC). An RVE or UC is the smallest volume over which a measurement can be made that will yield a value representative of the whole. RVEs and UCs are widely used in the characterisation of materials with multiscale archite...
The fabric structure of looped fabric reinforced laminate (LFRL) was investigated based upon braiding process and microscopy imaging. Fiber bridging in double cantilever beam (DCB) specimens manufactured of plain weave fabric laminate (PW) and LFRL was studied experimentally. An FE model for LFRL DCB specimen considering large-scale bridging was de...
A damage model for linear viscoelastic unidirectional (UD) composites undergoing transverse matrix cracking is proposed. The damage representation for the corresponding elastic UD composite with an array of dispersed matrix cracks was derived from Li’s work based on continuum damage mechanics (CDM). The elastic-viscoelastic correspondence principle...
With the development of finite element (FE) codes, numerical modelling of delamination is often considered to be somewhat commonplace in modern engineering. However, the readily available modelling techniques often undermine the truthful understanding of the nature of the problem. In particular, a critical review of the representativeness of the nu...
An innovative research front for composites is their production by additive manufacturing (AM), also referred to as 3D printing. AM, which was previously mainly used for prototyping, is now evolving towards functional components. Part of the motivation in the search for AM developments to fibre composites is to explore the inherent flexibility of t...
Schwarz P unit cell-based tissue scaffolds comprised of poly(D,L-lactide-co- ε -caprolactone)(PLCL) fabricated via the additive manufacturing technique, two-photon polymerisation (2 P P) were found to undergo geometrical transformations from the original input design. A Schwarz P unit cell surface geometry CAD model was reconstructed to take into a...
Application of a continuum damage mechanics formulation rests on the ease with which the material constants involved in the formulation can be determined. For an initially linear elastic material, the changes in elastic constants induced by damage depend on certain damage related material constants that are commonly determined by experiments in add...
Thermal expansion properties of textile reinforced composites with certain structure symmetries can be efficiently calculated by a size-limited unit cell. In this paper, a general approach is developed for the establishment of such a unit cell model. For the derivation of unit cell boundary conditions, three rules are summarized according to the di...
Popular failure criteria for fibre reinforced composites are subjected to critical scrutiny on their rationality. The rationality of a theory is about the mathematical and physical logic underlying the theory, rather than the closeness of their results in comparison with experimental data. Seeking for close comparisons with a set of experimental da...
The concept of full commutativity of displacements in the expression for strain energy density for the geometrically nonlinear problem has been introduced for the first time and fully established in this paper. Its consequences for the FEM formulation have been demonstrated. As a result, the strain energy, equilibrium equation and incremental equil...
Optimization design of thermal protection system of aerospace vehicles with progressively increasing flying speeds needs a deepened study on the thermal conduction characteristics of corresponding materials. As a potential thermal protection material, C/C-SiC 8-harness (8HS) satin woven composites with piercing fiber bundles are numerically studied...
This paper is to rationalise the empirical aspect of the Tsai-Wu failure criterion in the context of UD composites associated with the determination of the interactive strength property F12 based on the analytic geometry. It reveals that the condition of closed failure envelope cannot be satisfied by all UD composites and hence the restriction shou...
Effective thermal properties of macro composites with symmetric structures can be efficiently calculated by a size-limited representative unit cell. In this paper, a general rule of such unit cell formulation is developed. Two key steps are involved, the identification of structure symmetries and the derivation of boundary conditions, in which the...
![Figure 1.5 E-bike annual sales in Europe from 2006 to 2014 [22].](profile/Alexander-Konyukhov-3/publication/320216159/figure/fig29/AS:660936734023681@1534591005268/E-bike-annual-sales-in-Europe-from-2006-to-2014-22_Q320.jpg)
![Figure 2.1 force on vehicle [99]](profile/Alexander-Konyukhov-3/publication/320216159/figure/fig30/AS:660936734015489@1534591005427/force-on-vehicle-99_Q320.jpg)
Thesis of L. Zhang submitted to The University of Nottingham, Ningbo, China
for the degree of Doctor of Philosophy
China currently occupies the world’s leading Electric bicycle (e-bike) market. However, the popularity of e-bikes is accompanied by massive numbers of injuries and deaths due to accidents involving e-bikes. As a result, the safety of...
In cross-ply laminates, the shape of delamination areas, which form due to low velocity impact, have two subtle features, which have been observed consistently in numerous experiments. Those are the pointed delamination tips and the intact zone between the lobes of delamination. However, there have not been any account available in the literature h...
The objective of this chapter is to provide a comprehensive and systematic account on the subject of representative volume elements (RVEs) and unit cells (UCs). To construct an RVE or UC, intuition has been often perceived sufficient to facilitate the analysis, but down to the details, approaches taken turn out to be rather mythological. It will be...
Based on the structure of the full unit cell which is formulated by three translational symmetries, three further 180° rotational symmetries of three-dimensional (3D) four-directional braided composites are clarified in this paper. It is for the first time that each rotational symmetry is used to reduce the full unit cell to a half, quarter, and ei...
The applicability of Mohr-Coulomb (M-C) failure hypothesis for anisotropic composite materials is reexamined in this paper. Mohr-Coulomb failure theory has been widely referred to in the literature to study the failure of unidirectional (UD) fibre reinforced composites under transverse loading including the renowned Puck's criteria. This has been p...
An approach is proposed to predict the thermal contact resistance (TCR) of rough surfaces. The practical rough topography of surfaces is measured by a contour profiler and is reconstructed to numerically analyze the mechanical and thermal contact performance. The studied material pairs are Ti-6Al-4V?Ti-6Al-4V and C/C-SiC?high temperature ceramic (H...
Generalized plane strain state is assumed and stress based finite strip method is formulated for analysis of unidirectional laminates with matrix micro cracks. Total complementary potential energy is minimized and fourth order Euler Lagrange governing equations are presented. This stress based generalized plane strain approach analyses general layu...
Unit cells in conjunction with micromechanical finite-element analysis have been widely used as a means for material characterisation of modern composites. However, they have been mostly applied in an ad hoc manner based on individual cases. Their implementation is often a demanding task for most unit-cell users, even with the formulation given in...
Side falling test is a necessary procedure in the design of an e-bike protective shell. The safety feature of the protective shell can be revealed by side falling motion simulation. The goal of safety measure during severe collision is to prevent over-turning by introducing a pair of protective side shells. The geometry of the protective shell must...
The performance of steel riser repaired with fibre reinforced polymer composite (FRPC) subjected to bending load was evaluated. Finite element (FE) analysis was used to simulate the load-strain behaviour of the repaired system. Accuracy of the model was validated against a simplified four-point bending experiment which was scaled to a significantly...
Single lap joints of woven glass fabric reinforced phenolic composites, having four different overlap widths, were impacted transversely using a hemispherical impactor with different velocities in the low velocity impact range. The resulting damage was observed at various length scales (from micro to macro) using transmission photography, ultrasoni...
The use of relatively inexpensive, high strength to weight ratio fiber reinforced polymer composite (FRPC) as a load bearing pipe repair sleeve is an emerging technology that is becoming common for offshore applications. This chapter will first outline the conventional offshore riser repair techniques and their limitations which, in turn, provide t...
China is currently the world's largest producer and distributor of the electric bicycles (e-bike). The increasing number of e-bikes on the road is accompanied by rising injuries and even deaths of e-bike drivers. Therefore, there is a growing need to improve the safety structure of e-bikes. This 3D frictionless contact analysis is a preliminary, bu...
Oil and gas pipelines are susceptible to various forms of damage where repair mechanisms have since been developed for rehabilitation. Once installed, structural health monitoring often incurs excessive costs and defects rectification of the repaired pipeline becomes a major challenge. Finite element analysis (FEA) provides a rapid route to predict...
Single lap joints of woven glass fabric reinforced phenolic composites, having four different overlap widths, were impacted transversely using a hemispherical impactor with different velocities in the low velocity impact range. The resulting damage was observed at various length scales (from micro to macro) using transmission photography, ultrasoni...
The samples of sintered Ag joints for power die attachments were prepared using paste of Ag nanoparticles at 240°C and 5 MPa for 3 to 17 minutes. Their microstructural features were quantitatively characterized with scanning electronic microscopy, transmission electron microscopy, X-ray diffraction and image analysis method. The resulting normalize...
In a manner reminiscent to establishing the 'periodic table', researchers and keen material scientists/engineers have been engaged in intensive activities trying to identify their own characteristic model or discover a unique aspect/failure mode in a composites material. No tangible progress could have possibly been achieved without the relentless...
The stress–strain response of an offshore pipe riser subjected to combined internal pressure, tension and bending is studied. Finite element analysis was used to study three conditions of pipe riser – uncorroded, corroded and corroded and repaired with designated laminate orientation of carbon/epoxy or E-glass/epoxy fibre-reinforced composite. The...
Unit cells have been proven to be an effective tool for material characterisation in conjunction with the use of finite element method (FEM) to predict the effective properties of composites. A key step in the application of unit cells is to impose periodic boundary conditions to the unit cells concerned. Successful imposition of such boundary cond...
This paper gives details of the input data and a full description of a set of 13 test cases provided to the participants of the third world-wide failure exercise for use in their theoretical models. World-wide failure exercise is aimed at benchmarking leading methods, capable of predicting initiation and progression matrix cracking and damage and f...
This paper provides a set of concluding remarks on Part A of the third world-wide failure exercise where a comparison has been made between the capabilities of 12 different mathematical models for predicting the evolution of matrix cracking, damage and failure in continuous fibre-reinforced polymer composites when subjected to multi-axial loading....
The authors have recently completed two world-wide failure exercises, which dealt with benchmarking recognised failure criteria under two-dimensional and three-dimensional loadings, respectively. A new phase, called the ‘third world-wide failure exercise’ is currently underway to fill some of the major gaps identified in the previous activities. Th...
Various approaches can be found in the literature for the analysis of transversely cracked laminates, e.g. shear lag, variational approach, stress transfer, continuum damage mechanics, finite elements and finite strips. Most of them are generically restrictive in one respect or another. This work extends the already developed finite strip method wh...