# Acoustic Emission-Based Method for IFSS Characterization in Single-Fiber Fragmentation Tests  
[PERSON]  
1 Departamento de Ingenieria Mecanica (DIM), Facultad de Ingenieria (FI), Universidad de Concepcion, Concepcion 4070490, Chile; [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (F.M. ); [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (A.S.)  
[PERSON]  
1 Departamento de Ingenieria Mecanica (DIM), Facultad de Ingenieria (FI), Universidad de Concepcion, Concepcion 4070490, Chile; [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (F.M. ); [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (A.S.)  
[PERSON]  
2 Instituto de Geologia Economica Aplicada, Universidad de Concepcion, P.O. Box 160-C, Concepcion 4070386, Chile; [PERSON]DDRESS] 2  
[PERSON]  
3 Department of Mechanical Engineering, Universidad de La Frontera, Temucao 4811230, Chile; [EMAIL_ADDRESS] 3  
[PERSON]  
1 Departamento de Ingenieria Mecanica (DIM), Facultad de Ingenieria (FI), Universidad de Concepcion, Concepcion 4070490, Chile; [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (F.M. ); [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (M.V. ); [EMAIL_ADDRESS] (A.S.)  
[PERSON]  
1 Departamento de Ingenieria Mecanica (DIM), Facultad de Ingenieria (FI), Universidad de Concepcion, Concepcion 4070490, Chile; [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (F.M. ); [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (C.M. ); [EMAIL_ADDRESS] (A.S.)  
[PERSON]  
4 Escuela de Ingenieria Mecanica, Pontificia Universidad Catolica de Valparaiso, Valparaiso 2340025, Chile  
[PERSON]  
1 Departamento de Ingenieria Mecanica (DIM), Facultad de Ingenieria (FI), Universidad de Concepcion, Concepcion 4070490, Chile; [EMAIL_ADDRESS] (F.R. ); [EMAIL_ADDRESS] (F.M. ); [EMAIL_ADDRESS] (C.  
the strength and toughness of the final composite [3; 4]. This parameter is mainly affected by hydroxyl and carboxylic functional groups on the fiber surface and interlocking caused by fiber morphology [5]. In the literature, several surface treatments have been proposed to improve fiber-matrix adhesion, including oxidation processes, plasma and laser treatments [6; 7], sizing [8; 9], chemical vapor deposition [9], and other multiscale reinforcements [10; 11; 12]. Due to the critical role of IFSS in composite performance, the mechanical characterization of interfacial bonding has become a subject of considerable research interest. Over the past decades, several techniques have been developed to quantify this parameter and are classified into microscale and macroscale approaches. Microscale methods include the micro bond-test [13], single fiber pull-out [14], single fiber push-out [15], and single fiber fragmentation test [16; 17; 18]. These techniques enable the decomposition of the composite's overall behavior into simplified fiber-matrix interactions, allowing a more isolated study of adhesion mechanisms. Identifying key interfacial parameters--such as IFSS, interfacial fracture toughness (IFFT), and coefficient of interfacial friction (\(u_{i}\))--is crucial, as it enables the analysis and description of interfacial debonding and fracture processes in composite materials through numerical simulations and analytical models [5; 19]. Complementary to these microscale techniques, meso- and macroscale methods have emerged as a convenient alternative for the indirect evaluation of interfacial shear strength, particularly due to their lower experimental complexity. Among the most reported are the transverse tensile test [13], 45\({}^{\circ}\) tension test [20], fiber bundle pull-out test [3], and Iosipescu shear test [21]. Among the microscale methods, the single fiber fragmentation technique (SFFT) is the simplest to implement in terms of instrumentation, as it requires basic microscopes and universal testing machines. This method consists of a fiber embedded in a straight or dog bone-shaped matrix subjected to a controlled tensile state.