Traditional composites, including polymer matrix composites (PMCs), metal matrix composites (MMCs), and ceramic matrix composites (CMCs), have been widely investigated for decades. Usually, lightweight characteristic is the eternal pursuit of the composites and their structures for engineering applications, in order to improve the effective load and lower the cost. Previous works simply focused on the lightweight design of composites and structures but merely focused on the functional design of composites and structures for various engineering application environments, such as high mechanical load, high-temperature, corrosion, low thermal expansion, wave absorption, wave transmitting, and vibration suppression. Therefore, how to combine the lightweight and multifunctional characteristics has attracted much attention recently.

Therefore, the integrated lightweight and multifunctional composites and structures, which mean the composites and structures, not only exhibit the lightweight behavior but also present multifunctional characteristics (e.g., load bearing, protective, ablative, heat insulated, wave absorbing and transmitting, vibration suppressing, explosion resisted, low thermal expansive, and anticorrosive). The main challenges involved in integrated lightweight and multifunctional composites and structures, such as design theory and method, fabrication technology, and characterization method, need to be specially focused on and studied.

The aim of this special issue is to publish the latest research progress and findings in the field of integrated lightweight and multifunctional composites and structures and to promote the applications of integrated lightweight and multifunctional composites and structures for engineering. The papers about the novel design theories and methods, fabrication technology and processing methods, and characterization methods are encouraged to be submitted to this special issue.

Potential topics include but are not limited to the following:

• Lightweight composites and structures with high load bearing capacity
• Lightweight composites and structures with thermal protective behavior or explosion protection behavior
• Lightweight composites and structures with wave absorbing or transmitting behavior
• Lightweight composites and structures with low thermal expansive or negative Poisson's ratio
• Additive manufacturing of lightweight composites and structures
• Advanced characterization methods and equipment for lightweight composites and structures