Recently composite materials have dominated most engineering fields, owing to their better performance, increased durability and flexibility to be customized and designed for a specific required property. This has given them unprecedented superiority over conventional materials. With the help of the ever increasing computational capabilities of computers, researchers have been trying to develop accurate material models for the complex and integrated properties of these composites. This has led to advances in virtual testing of composite materials as a supplement or a possible replacement of laboratory experiments to predict the properties and responses of composite materials and structures. This paper presents a review on the complex multi-scale modelling framework of the virtual testing machines, which involve computational mechanics at various length-scales starting with nano-mechanics and ending in structure level computational mechanics, with a homogenization technique used to link the different length scales. In addition, the paper presents the features of some of the biggest integrated virtual testing machines developed for study of concrete, including a multiscale modeling scheme for the simulation of the constitutive properties of nanocomposites. Finally, the current challenges and future development potentials for virtual test machines are discussed.

Abstract
 1. Introduction
 2. Virtual testing machines
  2.1 What is virtual testing?
  2.2 Components of a multiscale virtualexperiment
  2.3 Length scales in virtual testing
 3. Some virtual laboratories and their features
  3.1 Virtual Test Facility(VTF) at CaltechCenter
  3.2 Virtual Cement and Concrete TestingLaboratory(VCCTL)
  3.3 DuCOM, COM3 and WCOMD: Durabilitymodels of concrete
  3.4 A multiscale modeling scheme for theconstitutive property determination ofnanocomposites
 4. Challenges of virtual testing and the futureprospect
 5. Concluding remarks
 References
 요 지

• Bezawit F. Haile(한국과학기술원 건설 및 환경공학과)
• 박솔뫼(한국과학기술원 건설 및 환경공학과) | S.M. Park (Department of Civil and Environmental Engineering, Korea Institute of Science and Technology(KAIST))
• 양범주(한국과학기술연구원 복합소재기술연구소) | B.J. Yang (Institute of Advanced Composite Materials, Korea Institute of Science and Technology(KIST))
• 이행기(한국과학기술원 건설 및 환경공학과) | H.K. Lee (Department of Civil and Environmental Engineering, Korea Institute of Science and Technology(KAIST)) Corresponding author