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Conventional sportswear design does not take into account body size changes that many individuals experience (e.g. through pregnancy, puberty, menstruation, etc.). This paper aims to detail both the construction of a novel wearable shape-adaptive composite and a new meso-scale material design method, which enables the optimal creation of these structures.

This work reports the development of a predictive computational model and a corresponding design tool, including results of a tensile testing protocol to validate their outputs. A mathematical model was developed to explore the geometric parameter space of a bi-stable composite system, which then feeds into an optimization design tool.

The authors found that it is possible to fabricate shape-adaptive composites via 3D printing bi-stable structures, and adhering them to a base textile. Experimental mechanical tensile testing showed good agreement with the predictive model in mid-range unit cell amplitude designs. To illustrate how the optimization design tool works this paper details two design examples, one for expected shape change during pregnancy and one for targeted compression for high performance swimwear. The optimized design parameters are shown to replicate the target parameters, however there is potential for further improvement with a lower stiffness base textile.

Although there is a wealth of research on multi-stable mechanisms, there is a dearth of studies that apply these structures in the wearable composite space. Additionally, there is a need for design methods which leverage the structurally-programmable capabilities of multi-stable structures to create optimized, high-performance functional composites.

The purpose of the present study is to explore the incomplete substitution of the simplex triangular finite element by either of two models: one evolving out as part of the element flexibility, and the other as part of the element stiffness.

The elastic energy stored in each of the units under stress or strain decides on stiffer and weaker responses. The pertaining Rayleigh quotient in terms of the flexibility matrices allows bounding the distance of the spring cell models to the finite element in dependence of the triangle configuration.

Despite a superiority of the flexibility cell concept observed in computations, the study reveals constellations of shape and stressing of the triangle that favour the stiffness concept. The latter is seen to behave stiffer than its flexibility counterpart and produces results more distant to the finite element in most cases.

The difference between the stiffness and the flexibility approach to spring cells is investigated for triangular elements in dependence of the geometrical configuration under specific conditions of stressing. This suffices to refute an exclusive superiority of the flexibility concept although largely true.

The results of the investigation appear useful in deciding between the spring cell models depending on the case of a spring lattice application.

The flexibility approach to the spring cell is not widely known yet. This cell model deserves a study on performance and comparison to the different, more common stiffness cell model.

The employment of spring cell substitutes for the numerical analysis of solids and structures in place of finite elements has occasioned research on the subject with regard to both, the applicability of existing approaches and the advancement of concepts. This paper aims to explore in the context of linear elasticity the substitution of the simplex tetrahedral element in space and the triangle in the plane by corresponding spring cells deduced on a flexibility basis using the natural formalism.

The natural formalism is characterized by the homogeneous definition of strain and stress along the lines connecting nodes of the simplex tetrahedron and the triangle. The elastic compliance involves quantities along the prospective spring directions and offers itself for the transition to the spring cell. The diagonal entities are interpreted immediately as spring flexibilities, the off-diagonal terms account for the completeness of the substitution. In addition to the isotropic elastic material, the concept is discussed for anisotropic elasticity in the plane.

The natural point of view establishes the spring cell as part of the continuum element. The simplest configuration of pin-joined bars discards all geometrical and physical cross effects. The approach is attracting by its transparent simplicity, revealing deficiencies of the spring cell and identifying directly conditions for the complete substitution of the finite element.

The spring cell counterparts of the tetrahedral- and the triangular finite elements allow employment in problems in three and two dimensions. However, the deficient nature of the approximation requires attention in the design of the discretization lattice such that the conditions of complete finite element substitution are approached as close as possible.

Apart from plane geometries, triangular spring cells have been assembled to lattice models of space structures such as membrane shells and similar. Tetrahedral cells have been used, in modelling plates and shell structures exhibiting bending stiffness.

The natural formalism of simplex finite elements in three and two dimensions is used for defining spring cells on a flexibility basis and exploring their properties. This is a novel approach to spring cells and an original employment of the natural concept in isotropic and anisotropic elasticity.

An intended numerical analysis of solids and structures by spring cell substitutes in place of finite elements has occasioned considerable research on the subject. This paper aims to expose two alternative concepts evolving out of Argyris’ natural approach to the simplex triangular element. One is based on an approximation of the element flexibility and the other approximates the stiffness with coincidence at the ideal conditions of complete substitution.

Characteristic of the natural formalism is the homogeneous definition of strain and stress along the sides of the triangular element. The associated elastic compliance offers itself for the transition to the spring cell. The diagonal entities are interpreted immediately as springs along the element sides, and the off-diagonal terms account for the completeness of the substitution. In addition to the flexibility concept, the spring cell is deduced alternatively from the element’s natural stiffness. The difference in the flexibility result lies in the calculatory cross-sectional areas of the elastic bar members.

From the natural point of view, the spring cell evolves out of the continuum element to the desired degree of substitution. The simplest configuration of pin-joined bars discards all geometrical and physical cross effects. The approach is attractive because of its transparent simplicity.

The difference between the stiffness and the flexibility approach to spring cells is demonstrated for triangular elements that suit the problems lying in plane stress or plane strain. More general states of stress and strain involve spring cell counterparts of the tetrahedral finite element.

Apart from plane geometries, triangular spring cells are assembled to lattice models of space structures, such as membrane shells and similar.

The natural formalism of simplex finite elements is used for deducing spring cells in two variants and exploring their properties. This is a novel approach to spring cells and an original employment of the natural concept.

Terrorists’ threats pose a grave danger to the health care environment in which we live. In the following paper, we look at how bioterrorist plots can effect a given population and show ways to dissect terrorist actions. We look at variables that use various cause and effect relationships, and lead the reader down a path of being able to use information presented in a real life or fictitious bioterrorist attacks. We seek to inform the reader reasons why preparedness is essential in dealing with the likelihood of the following scenarios.

In order to investigate the vibration reduction properties of a three-dimensional elastic metastructure with spherical cavities at low frequencies.

The bandgap characteristics of a three-dimensional elastic metastructure with spherical cavities are studied based on analytical and numerical approaches.

The results of both method revealed that the vibration of the vertexes masses is important for opening bandgaps. The fact that the big sphere cavity radius or short side length of the cube unit leads to a wider bandgap, is noteworthy.

This research provides theoretical guidance for realizing the vibration attenuation application of EMs in practical engineering.

Series elastic actuators provide many benefits in force control of robots in unconstrained environments. These benefits include high force fidelity, extremely low impedance, low friction, and good force control bandwidth. Series elastic actuators employ a novel mechanical design architecture which goes against the common machine design principal of “stiffer is better”. A compliant element is placed between the gear train and driven load to intentionally reduce the stiffness of the actuator. A position sensor measures the deflection, and the force output is accurately calculated using Hooke’s Law (F = Kx). A control loop then servos the actuator to the desired output force. The resulting actuator has inherent shock tolerance, high force fidelity and extremely low impedance. These characteristics are desirable in many applications including legged robots, exoskeletons for human performance amplification, robotic arms, haptic interfaces, and adaptive suspensions.

Springs are an integral part of mechanisms and can benefit from additive manufacturing’s (AM) increased design freedom. Given the limited literature on the subject, the purpose of this paper is to develop guidelines for fabricating helical springs using three-dimensional (3D) printing.

Polylactic acid (PLA) is the main material investigated, with ULTEM™ 9085 used as a comparison. The experimental procedure is to vary the spring parameters, print the springs and test them in tension or compression using constant velocity. Plots of the force and displacement are used to measure the linear and post-deformation spring constants. Loading of the springs is done both to breakage and cyclically. Cyclic loading is also used to observe the plastic behaviour of the springs. Parameters that are varied include wire and coil diameters, pitch, wire cross-section, in-fill and layer height.

A square wire cross-section is used, instead of a circle because it produces more consistent coils. In-fills make no significant difference in the elastic stiffness of the springs but the mono in-fill breaks at a greater extension, so it is recommended. Tension and compression springs are confirmed to behave the same when in the elastic regime. ULTEM™ 9085 produces consistently weaker springs compared to PLA. Variation of layer height shows that thinner layers increase the stiffness of the springs.

This study investigates the behaviour of 3D printed helical springs in tension and compression. Three guidelines are created: square wire cross-section, mono-directional in-fill and thin layers are recommended.

The purpose of this paper is to explore the applications and technological details of common components – rings and springs.

The characteristics and applications of compression springs and then extension springs are investigated, and various finishing techniques are reported. Rings ranging from flat washers to snap‐rings, push‐on rings and Smalley rings are presented.

The humble spring may be surprisingly high‐tech, with applications in fuel injection, pacemakers and insulin delivery systems. Springs fulfill shock absorption duties as well as securing tasks, and can pre‐load fixtures to withstand thermal expansion and vibration. Retaining rings are used in heavy duty lifting gear and wind turbines, whilst simple washers elegantly combine wear protection with insulation in securing circuit boards.

The paper highlights the continuing development and surprising strengths of some simple components.

Reports on the 1999 Manufacturing Week exhibition and in particular on the Automation, Production and Maintenance Equipment (APME) section. It highlights a number of assembly equipment vendors who increasingly are supplying flexible systems to meet the demand of smaller batch manufacture. A number of application examples are described, including assembly and test of weigh scales, a kettle base and a current sensor for white goods. Another prime technology identified is vision, which is becoming much more transparent in part‐feeding systems. Some vendors promoted the application of vision to robot guidance and an application is given of loading machining centres with several automotive castings delivered randomly on a fixtureless conveyor belt. Finally, a number of new transport systems introduced at the show are identified.