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In recent years, a novel method for computing loadflow orientations and loadpaths, which is based on iterative solutions of non‐linear equations and finite element results, has emerged in the literature. In the present investigation, the prior formulation and approach has been enhanced by deriving explicit expressions for computing loadflow orientations. The new equations produce more accurate loadflow orientations and improve the fidelity of calculated loadpaths. In particular, for a typical loaded plate containing a hole, the density of loadflow lines is also shown to provide accurate values of stress concentration factor. Subsequently, loadflow visualisation for biaxially loaded plates containing non‐optimal and optimal holes is undertaken to identify key features of the stress distributions. It is found that regions of “recirculation” are apparent for non‐optimal hole shapes, whereas no recirculation zones are present for optimal shapes. In general, it is considered that loadflow visualisation is a simple but powerful tool for use by structural designers and analysts.

The purpose of this paper is to present several methods on how to deal with yield surface discontinuities. The explicit formulations, first presented by Koiter (1953), result in multisingular constitutive matrices which can cause numerical problems in elasto-plastic finite element calculations. These problems, however, are not documented in previous literature. In this paper an amendment to the Koiter formulation of the constitutive matrices for stress points located on discontinuities is proposed.

First, a review of existing methods of handling yield surface discontinuities is given. Examples of the numerical problems of the methods are presented. Next, an augmentation of the existing methods is proposed and its robustness is demonstrated through footing bearing capacity calculations that are usually considered “hard”.

Previous studies documented in the literature all present “easy” calculation examples, e.g. low friction angles and few elements. The amendments presented in this paper result in robust elasto-plastic computations, making the solution of “hard” problems possible without introducing approximations in the yield surfaces. Examples of “hard” problems are highly frictional soils and/or three-dimensional geometries.

The proposed method makes finite element calculations using yield criteria with corners and apices, e.g. Mohr-Coulomb and Hoek-Brown, much more robust and stable.

The mesoscale structure (MS) has a significant impact on the mechanical performance of parts made by additive manufacturing (AM). This paper aims to explore the design and fabrication of force-flow guided reinforcement mesoscale structure (FFRMS) compared with the homogeneous mesoscale structure (HMS), which is inconsistent with the stress field for a given load condition. Some cases were presented to demonstrate the mechanical properties of FFRMS in terms of MS combined with quasi-isotropy and anisotropy.

The paper consists of four main sections: the first developed the concept of FFRMS design based on HMS, the second explored volume fraction control for the proportion of force-flow lines in terms of mechanical property requirement, and the third presented a sequence stacking theory and practical manufacturing process framework and the final sections provided some application case studies.

The main contributions of this study were the definition and development of the FFRMS concept, the application framework and the original case studies. As an example, a typical lug designed with the proposed FFRMS method was fabricated by three different AM processes. The test results showed that both the strength and stiffness of the specimens are improved greatly by using the FFRMS design method.

The superposition of HMS as the basement and force-flow as an indication of the stiffener, leading to a heterogeneous structure, which exhibits more efficient and diversified means compared with the traditional way of increasing the HMS density merely.

NOTWITHSTANDING the fact that there exists a considerable amount of literature published in various forms on the subject of brittle lacquers and their applications to a multitude of diverse problems a brief resume of some of the general principles involved would seem not to be out of place.

The determination of load paths is an essential element of structural design. Load paths provide insight into the way the structure is performing its prescribed function. They can also indicate possibilities for shape optimization and the effect of component modification or damage. They are relatively easy to define in simple structures such as trusses which comprise a finite number of clearly defined members which carry only axial load. The load path is given simply by tracing the higher axial loads through the structure. However, for continua such as plates or solids, there is currently no systematic procedure for determining the path of load from the point of application to the constrained boundaries. This paper addresses the problem of defining the path of loads in plates with geometric discontinuities and in simple joints. The theory associated with the determination of the load path is first introduced, and then integrated into a finite element package to provide pictorial contours.

This paper aims to numerically study the effects of boundary conditions, pre-stress, material constants and thickness on the dynamic performance of a wrinkled thin membrane.

Based on the stability theory of plates and shells, the dynamic equations of a wrinkled thin membrane were developed, and they were solved with the Lanczos method

The effects of wrinkle-influencing factors on the dynamic performance of a wrinkled membrane are determined by the wrinkling stage. The effects are prominent when wrinkling deformation is evolving, but they are very small and can hardly be observed when wrinkling deformation is stable. Mode shapes of a wrinkled membrane are sensitive to boundary conditions, pre-stress and Poisson’s ratio, but its natural frequencies are sensitive to all these five factors.

The research work in this paper is expected to help understand the dynamic behavior of a wrinkled membrane and present access to ensuring its dynamic stability by controlling the wrinkle-influencing factors.

Very few documents investigated the dynamic properties of wrinkled membranes. No attention has yet been paid by the present literature to the global dynamic performance of a wrinkled membrane under the influences of the factors that play a pivotal role in the wrinkling deformation. In view of this, this paper numerically studied the global modes and corresponding frequencies of a wrinkled membrane and their variation with the wrinkle-influencing factors. The results indicate that the global dynamic properties of a wrinkled membrane are sensitive to these factors at the stage of wrinkling evolution.

The purpose of this paper is to develop a heuristic method for topology optimization of a continuum with bi-modulus material which is frequently occurred in practical engineering.

The essentials of this model are as follows: First, the original bi-modulus is replaced with two isotropic materials to simplify structural analysis. Second, the stress filed is adopted to calculate the effective strain energy densities (SED) of elements. Third, a floating reference interval of SED is defined and updated by active constraint. Fourth, the elastic modulus of an element is updated according to its principal stresses. Final, the design variables are updated by comparing the local effective SEDs and the current reference interval of SED.

Numerical examples show that the ratio between the tension modulus and the compression modulus of the bi-modulus material in a structure has a significant effect on the final topology design, which is different from that in the same structure with isotropic material. In the optimal structure, it can be found that the material points with the higher modulus are reserved as much as possible. When the ratio is far more than unity, the material can be considered as tension-only material. If the ratio is far less than unity, the material can be considered as compression-only material. As a result, the topology optimization of continuum structures with tension-only or compression-only materials can also be solved by the proposed method.

The value of this paper is twofold: the bi-modulus material layout optimization in a continuum can be solved by the method proposed in this paper, and the layout difference between the structure with bi-modulus material and the same structure but with isotropic material shows that traditional topology optimization result could not be suitable for a real bi-modulus layout design project.

Thick cylinder. This experiment is designed to confirm the usual Lamé theory for thick cylinders subjected to internal pressure.

Cantilever. In this experiment a mild steel cantilever beam is arranged so that it cannot be over‐strained. The end travel is limited by contact with the base of the apparatus when fully deflected, see Figure 1.

A set of algorithms has been developed and evaluated for 3D and 21/2D rapid prototyping replication of 3D reconstructions of cancellous bone samples. The algorithms replicate a voxel map without any loss of fidelity, so as to increase the validity of the comparison of mechanical tests on the 3D reconstructed models with those predicted by finite element analyses. The evaluation is both in terms of algorithmic complexity and the resultant data set size. The former determines the feasibility of the conversion process, whereas the latter the potential success of the manufacturing process. The algorithms and their implementation in PC software is presented.