Table 3.

Summary of AI-enabled DTs in smart manufacturing: process and material level (Section 2.4).

Subfield	AI-Category	Key Methods	Application-Case	Ref.
Metal Cutting (Section 2.4.2.1)	Supervised Learning	PIO, SVM	Prediction of surface roughness	[195]
		Ensemble methods, ANN	Modeling of the rheological behavior of drilling fluids	[196]
		ANN	Prediction of stress and fatigue damage (FE surrogate) of flexible risers	[197]
		DNA-based computing, Markov chain	Prediction of surface roughness	[198]
	Reinforcement Learning	DDPG	Optimization of decision-making based on performance and machinability of parts	[199]
	Computational Intelligence	PSO	Inverse determination of material model parameters from cutting simulation	[200]
Metal AM and Laser Material Processing (Section 2.4.2.2)	Supervised Learning	SVM	Prediction of the occurrence of defects in metal AM (LPBF, LMD)	[201]
		CNN, LSTM, RNN	Quality assurance in metal AM (LPBF)	[202]
		CART	Prediction of additive manufacturability	[203]
		HMM	Model adaptivity and quality assessment of laser material removal processes	[204]
	Unsupervised Learning	k-means	Anomaly detection and process optimization of 3D laser cutting processes	[205]
Composite Material Processing (Section 2.4.2.3)	Supervised Learning	CNN, transfer learning	Detection of dry points in the production of carbon fiber reinforced plastics	[206]
		AdaBoost, XGBoost, RF	Prediction of temperature distribution of thermoplastic composites	[207]
		DNN	FE surrogate for a composite textile draping process	[208]
		PML	Prediction of material properties of a composite material system	[209]
	Computational Intelligence	ISRES	Identification of material parameters of a prepreg sheet	[210]
Joining	Supervised Learning	DNN, GA	Prediction of distortion in welding	[211]
Forming	Supervised Learning	ANN	Prediction of the ingate velocity during sand mold filling	[212]

PIO: Pigeon-Inspired optimization; DDPG: Deep Deterministic Policy Gradient; PSO: Particle Swarm Optimization; HMM: Hidden Markov Model; PML: Probabilistic Machine Learning; ISRES: Improved Stochastic Ranking Evolution Strategy.