A Discrete Process Modelling and Simulation Methodology for Industrial Systems within the Concept of Digital Twins

A generic well-defined methodology for the construction and operation of dynamic process models of discrete industrial systems following a number of well-defined steps is introduced. The sequence of steps for the application of the method as well as the necessary inputs, conditions, constraints and the results obtained are defined. The proposed methodology covers the classical offline modelling and simulation applications as well as their online counterpart, which use the physical system in the context of digital twins, with extensive data exchange and interaction with sensors, actuators and tools from other scientific fields as analytics and optimisation. The implemented process models can be used for what-if analysis, comparative evaluation of alternative scenarios and for the calculation of key performance indicators describing the behaviour of the physical systems under given conditions as well as for online monitoring, management and adjustment of the physical industrial system operations with respect to given rules and targets. An application of the proposed methodology in a discrete industrial system is presented, and interesting conclusions arise and are discussed. Finally, the open issues, limitations and future extensions of the research are considered.

In Silico Trial Approach For Biomedical Products: A Regulatory Perspective

The modern pharmaceutical industry is creating a transition from traditional methods to advanced technologies like artificial intelligence. In the current scenario, continuous efforts are being made to incorporate computational modelling and simulation in drug discovery, development, design, and optimization. With the advancement in technology and modernization, many pharmaceutical companies are approaching in silico trials to develop safe and efficacious medicinal products. To obtain marketing authorization for a medicinal product from the concerned National regulatory Authority, manufacturers must provide evidence for the safety, efficacy, and quality of medical products in the form of in vitro or in vivo methods. However, more recently this evidence was provided to regulatory agencies in the form of modelling and simulation, i.e., in silico evidence. Such evidence (computational or experimental) will only be accepted by the regulatory authorities if it considered as qualified by them and this will require the assessment of the overall credibility of the method. One must consider the scrutiny provided by the regulatory authority to develop or use the new in silico evidence. The United States Food and Drug Administration and European Medicines Agency are the two regulatory agencies in the world that accept and encourage the use of modelling and simulation within the regulatory process. More efforts must be made by other regulatory agencies worldwide to incorporate such new evidence, i.e., modelling and simulation (in silico) within the regulatory process. This review article focuses on the approaches of in silico trials, its verification, validation, and uncertainty quantification involved in the regulatory evaluation of biomedical products that utilize predictive models.

Development of VUMAT and VUHARD Subroutines for Simulating the Dynamic Mechanical Properties of Additively Manufactured Parts

Numerical modelling and simulation can be useful tools in qualification of additive manufactured parts for use in demanding structural applications. The use of these tools in predicting the mechanical properties and field performance of additive manufactured parts can be of great advantage. Modelling and simulation of non-linear material behaviour requires development and implementation of constitutive models in finite element analysis software. This paper documents the implementation and verification process of a microstructure-variable based model for DMLS Ti6Al4V (ELI) in two separate ABAQUS/Explicit subroutines, VUMAT and VUHARD, available for defining the yield surface and plastic deformation of materials. The verification process of the implemented subroutines was conducted for single and multiple element tests with varying prescribed loading conditions. The simulation results obtained were then compared with the analytical solutions at the same conditions of strain rates and temperatures. This comparison showed that both developed subroutines were accurate in predicting the flow stress of various forms of DMLS Ti6Al4V (ELI) under different conditions of strain rates and temperatures.