Although the concept of additive manufacturing has been proposed for several decades, momentum in the area of selective laser melting (SLM) is finally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization during SLM to obtain high relative density and low surface roughness simultaneously in the literature. In this work, the response surface method was adopted to study the influences of different processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. A statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main effects of processing parameters on the density and surface roughness are similar. We observed that the laser power and scanning speed significantly affected the above objective quality, but the influence of the hatch spacing was comparatively low. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.

Mechanical computing promises to integrate semiconductor‐based digital logic in several applications, but it needs straightforward programmable devices for changing computing rules in situ. A methodology based on strain‐governed, bistable soft shells that process digital information by interchanging their internal/external surfaces is proposed. This bistable behavior, explained via model‐based design, safeguards robustness by working only once for each input pulse. Thus, these shells are leveraged to create a buffer and a NOT gate that lead to six fundamental gates (AND, OR, NAND, NOR, XOR, and XNOR). All these functions are integrated into a unique programmable device, making mechanically integrated circuits more adaptable with rule‐changeable logic operations. This design ensures continuous processes and general applicability to multiple types of signals (a pressurized fluid can replace mechanical driving signals is shown). It also empowers more complex logic functions suitable for expanded applications, such as the half and full adders is addressed.

Mechanical computation outperforms electrical computation in applications under extreme conditions. Currently, logic gates can be constructed with mechanical metamaterials, but this may require complex architectures and computing rules, and more complex computations based on these gates are considerably more challenging. Mechanical computing systems with multistability cannot return to their initial stable states, which are hardly reused. Moreover, providing digital electrical outputs is useful to communicate with electrical systems. To address these issues, mechanical metamaterials can be integrated in a manner that is similar to a circuit network with a powerful computing capability. Herein, a general method that combines soft convex and concave modules, rigid frames, and conductive materials in one system to realize logic gates, addition, and multiplication is proposed. The soft modules make or break electrical connections with adjacent frames due to the presence or absence of compressive forces, operating as open and closed switches. Connections and disconnections between modules and frames can be demonstrated with conductive materials and LEDs. The proposed mechanism is simple, versatile, and reusable, allowing soft mechanical metamaterial units to carry out complex computations. The approach may improve the capabilities of soft robots, robotic materials, and microelectromechanical systems.

A new type of modular metamaterials with reprogrammable mechanical properties is proposed based on the multistability in decoupled units. This metamaterial consists of periodically arranged foldable obelisk-like (FO) units, and each unit has three interchangeable states: two different soft states and a stiff state. Therefore, such metamaterial can possess various mechanical properties with different state combinations of units. Both theoretical and experimental investigations are conducted to understand the multistability in one unit and the reprogrammed mechanical properties in a two-dimensional tessellation. Additionally, we investigate the inverse question that whether the identical force response can be generated with different geometrical design of the metamaterial and propose a way to build 3D metamaterials with intended architectures. This work establishes general principles for designing mechanical metamaterials with independently transformable modules, and opens new avenues for various potential applications such as: self-locking materials, impact mitigation and stiffness transformation materials.