Luca Collini | Università degli Studi di Parma (Italy) (original) (raw)

Papers by Luca Collini

Structural Dynamics, Volume 3, 2011

Anyone can freely access the full text of works made available as "Open Access". Works made avail... more Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law.

Materials, 2022

This study analyses the energy absorption and stiffness behaviour of 3D-printed supportless, clos... more This study analyses the energy absorption and stiffness behaviour of 3D-printed supportless, closed-cell lattice structures. The unit cell design is bioinspired by the sea urchin morphology having organism-level biomimicry. This gives rise to an open-cell lattice structure that can be used to produce two different closed-cell structures by closing the openings with thin or thick walls, respectively. In the design phase, the focus is placed on obtaining the same relative density with all structures. The present study demonstrates that closure of the open-cell lattice structure enhances the mechanical properties without affecting the functional requirements. Thermoplastic polyurethane (TPU) is used to produce the structures via additive manufacturing (AM) using fused filament fabrication (FFF). Uniaxial compression tests are performed to understand the mechanical and functional properties of the structures. Numerical models are developed adopting an advanced material model aimed at st...

Introduction. Gray cast iron is traditionally used in many industries because it is characterized... more Introduction. Gray cast iron is traditionally used in many industries because it is characterized by flexibility of use, excellent castability, low cost, wide range of achievable mechanical properties [1]. The Italian company Casappa SpA that produces gear pumps for the hydraulic power industry gave the motivation of this study. The company extensively uses pearlitic gray cast iron to manufacture pump bodies of complex three-dimensional shape that are subjected to dynamic service loading conditions. Product reliability requirements have motivated the development of efficient

The techniques of dynamic identification of structural characteristics of buildings are successfu... more The techniques of dynamic identification of structural characteristics of buildings are successfully employed since many years. On new constructions these techniques permit the study of the building response to lowor high-energy vibrations (i.e. to earthquakes) for a safe design, while on ancient/historical buildings they can be employed to monitor the healthiness of the construction i.e. detect any damage repeating the tests during some years. In this work we present an innovative vibrodyne we have designed with the aim of produce a bi-directional excitation harmonic force controlled in amplitude and frequency. This machine is portable, economic, and is suitable for the use into ancient or delicate buildings. In this work we present the preliminary results of a series of tests carried out on an ancient and vast castle undergone to a very elaborated structural investigation. A very interesting comparison between mechanical vibrodyne excitation vs. traditional impact hammer excitatio...

Shock and Vibration, 2017

Materials, 2021

Nowadays, fused deposition modeling additive technology is becoming more and more popular in part... more Nowadays, fused deposition modeling additive technology is becoming more and more popular in parts manufacturing due to its ability to reproduce complex geometries with many different thermoplastic materials, such as the TPU. On the other hand, objects obtained through this technology are mainly used for prototyping activities. For this reason, analyzing the functional behavior of FDM parts is still a topic of great interest. Many studies are conducted to broaden the spectrum of materials used to ensure an ever-increasing use of FDM in various production scenarios. In this study, the effects of several phenomena that influence the mechanical properties of printed lattice structures additively obtained by FDM are evaluated. Three different configurations of lattice structures with designs developed from unit cells were analyzed both experimentally and numerically. As the main result of the study, several parameters of the FDM process and their correlation were identified as possible ...

Material Design & Processing Communications, 2021

Procedia Structural Integrity, 2019

Shape-adaptive or morphing capability is regarded as significant to increase aerodynamic performa... more Shape-adaptive or morphing capability is regarded as significant to increase aerodynamic performance of airfoils employed in aerospace, wind turbines or race cars, while at the same time reducing the number of moving parts. The inherent bistable behavior of asymmetric cross-ply composites makes them as a suitable candidate for morphing applications with a small energy input, and an efficient way to switch between the two equilibrium configurations is given by embedded shape memory alloy (SMA) wires. However, when a bi-stable composite plate is integrated with SMA wires (Shape Memory Alloy Composite, SMAC), the identification of design parameters, namely laminate size and layup, composite elastic constants, SMA wires number and thermomechanical behavior, SMAC manufacturing cycle, is not straightforward. The present work described the strategies developed by the authors to model and optimize a SMAC subjected to bi-stability and post-manufacturing deflection requirements.

Procedia Structural Integrity, 2019

The purpose of this work is to evaluate the influence of co-lamination vs. co-bonding on the fail... more The purpose of this work is to evaluate the influence of co-lamination vs. co-bonding on the failure behavior, and namely the fracture toughness, of carbon fibre reinforced (CFR) composite laminate joints in order to assess comparatively their performance. Since the strength of the laminate and ply texture are parameters affecting the strength of the joint, the comparison is extended to two different types of CFR pre-preg fibers, a satin T1100 with 2573 Nanoalloy® epoxy resin supplied by Toray and a twill T700 with ER450 toughened epoxy resin supplied by CIT, Toray group, representative of two different fields of application, racing and automotive, respectively.

Frattura ed Integrità Strutturale, 2010

Materials, 2019

Shape-adaptive or morphing capability in both aerospace structures and wind turbine blade design ... more Shape-adaptive or morphing capability in both aerospace structures and wind turbine blade design is regarded as significant to increase aerodynamic performance and simplify mechanisms by reducing the number of moving parts. The underlying bistable behavior of asymmetric cross-ply composites makes them a suitable candidate for morphing applications. To date, various theoretical and experiential studies have been carried out to understand and predict the bistable behavior of asymmetric laminates and especially the curvature obtained in their stable configurations. However, when the bi-stable composite plate is integrated with shape memory alloy wires to control the curvature and to snap from a stable configuration to the other (shape memory alloy composite, SMAC), the identification of the design parameters, namely laminate edge length, ply thickness and ply orientation, is not straightforward. The aim of this article is to present the formulation of an optimization problem for the pa...

Fatigue & Fracture of Engineering Materials & Structures, 2017

generation algorithm available in the numerical code. To speed-up the analyses no check of the si... more generation algorithm available in the numerical code. To speed-up the analyses no check of the size and no check of the difference between the lengths of adjacent edges of an element are required; indeed, approximations are all included in the scatter band of the PSM. The following new part has been added to the revised manuscript to clarify this point: "The finite element size d has been intentionally taken as the 'global element size' input by the FE analyst before running the free mesh generation algorithm available in the FE code. Obviously, the edge lengths of the actually generated finite elements will fulfil the prescribed size d only approximately. Nevertheless, the average FE size d has been adopted in Eqs (3) and (4), the effects of the variability of the FE size in the vicinity of the V-notch tip being included in the scatter band of K FE * and K FE ** ." 3. Section 4.2 describes the loading in the shear case, mentioning prescribed displacements which correspond to a gross shear stress. The relation applies to an absent crack. But doesn't a crack weaken the plate so that this relation changes is such a case? Please clarify. Yes, the crack alters the uniform gross shear stress existing in the un-cracked case. In the crack case it is just a reference stress: please note that the same reference stress has been adopted to evaluate the exact SIF K 2 (using extremely refined FE meshes) and the sliding FE peak stress τ ΙΙ,peak (using coarse meshes according to the PSM). The exact SIF K 2 and the sliding peak stress τ ΙΙ,peak evaluated by using the same loading condition are input in Eq. (6) in order to calculate the normalised SIF K FE **. This has been clarified in the section 5.2 of the revised manuscript. 4. In Section 7.4 it is mentioned that the default options are highlighted in Tables 8 and 9 (also in the table captions). Do you mean 'default options indicated'? Thanks. Yes, we mean the 'default options indicated', we have modified both text and Table captions accordingly.

International Journal of Architectural Heritage, 2019

Tie-rods are essential structural elements, which have been employed for centuries in masonry his... more Tie-rods are essential structural elements, which have been employed for centuries in masonry historical buildings, either during the construction or in successive strengthening interventions, with the aim of containing dangerous horizontal actions. The actual work conditions of these tie-rods, which are strongly influenced by their load history, are difficult to be quantified theoretically, and an effective method for their measure is of great importance in order to ensure the efficiency of these elements during the time and the stability of the entire building. Common measurements are often carried out adopting models based upon significant simplifications, like, for example, hinges at the extremities. These assumptions, rarely represent the real work conditions for anchorages. In this work, a non-destructive testing method is presented, based upon sophisticated dynamical models that can take into consideration many of the circumstances neglected by the simplified models. Four case studies are extensively described, trying to embrace the most common situations in term of peculiar features of the building, structural configuration, and load history. The discussion of the results yields the safety margin of the rod with respect to the material failure and provides important indications about the overall stability of the whole building.

Archive of Applied Mechanics, 2017

Two cases of plane-parallel motion of a rigid body with flat basement over a horizontal plane wit... more Two cases of plane-parallel motion of a rigid body with flat basement over a horizontal plane with dry friction are considered. Conditions for the friction impact are obtained for a body performing gliding motion with spinning. For motion of a body in a vertical plane, collisions of the body with the supporting plane are considered. In the parameter space, a map of areas is constructed where the after-collision state of motion is similar.

Materials Today: Proceedings, 2017

This paper presents an experimental and numerical study of vibrations of loudspeakers. The experi... more This paper presents an experimental and numerical study of vibrations of loudspeakers. The experimental part consisted of measuring vibrational responses of cones of the loudspeakers to the sine sweep excitation signal. Acquisition was performed by means of a laser vibrometer. The numerical analysis employed finite element simulations of the cone and suspensions, based on estimation of viscoelastic properties for loudspeaker components. Having acquired accelerations of hundreds of points on the radiating surface, the radiated sound pressure level at one-meter distance has been computed. Confronting SPLs obtained from the two approaches the authors attempted to match the numerical model with the experiment. The matching was confirmed by the comparison between the simulated and measured operational deflection shapes.

Shock and Vibration, 2017

This paper presents an application of vibration analysis to the monitoring of tie-rods. An algori... more This paper presents an application of vibration analysis to the monitoring of tie-rods. An algorithm for the axial load estimation based on experimentally measured natural frequencies is introduced and its application to a case study is reported. The proposed model of a tie-rod incorporates elastic bed-type boundary conditions that represent the contact between stonework and the tie-rod. The weighed differences between experimentally and numerically determined frequencies are minimized with respect to the parameters of the model, the main being the axial load and the stiffness at the tie-rod/wall interface. Thus, the multidimensional optimization problem is solved. Results are analysed in comparison to a model with simple fixed-end boundary conditions. In addition, the analytical formulation of the problem is delivered.

Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, 2015

Interactions between buildings and earthquakes have been studied for a long time, and there is mu... more Interactions between buildings and earthquakes have been studied for a long time, and there is much literature about them. This research deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to control the vibrations; dry friction has also been considered. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method. From this theoretical standpoint, we derive many important analytical or numerical results, providing us the tools suitable for the design of absorbers in practical cases.

Shock and Vibration, 2016

This study deals with the dynamical evolutions exhibited by a simple mechanical model of building... more This study deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to reduce oscillations. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method, and dry friction has also been considered. From the analytical/numerical simulations, we derive some important conclusions, providing us with the tools suitable for the design of absorbers in practical cases.

Conference Proceedings of the Society for Experimental Mechanics Series, 2011

Anyone can freely access the full text of works made available as "Open Access". Works made avail... more Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law.

Key Engineering Materials, 2007

In this work the fatigue crack growth properties of friction stir welded butt joints are evaluate... more In this work the fatigue crack growth properties of friction stir welded butt joints are evaluated. Fatigue Crack Growth (FCG) tests have been carried out on two particle-reinforced aluminium alloys (AA6061/Al2O3/20p and AA7005/Al2O3/10p). FCG properties have been evaluated at the centre and at the side of the weld, respectively. The results are compared with FCG properties of base materials. The role of alumina in particles inside the matrix is evident in the threshold region: this can be explained in terms of Roughness Induced Crack Closure.

Structural Dynamics, Volume 3, 2011

Anyone can freely access the full text of works made available as "Open Access". Works made avail... more Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law.

Materials, 2022

This study analyses the energy absorption and stiffness behaviour of 3D-printed supportless, clos... more This study analyses the energy absorption and stiffness behaviour of 3D-printed supportless, closed-cell lattice structures. The unit cell design is bioinspired by the sea urchin morphology having organism-level biomimicry. This gives rise to an open-cell lattice structure that can be used to produce two different closed-cell structures by closing the openings with thin or thick walls, respectively. In the design phase, the focus is placed on obtaining the same relative density with all structures. The present study demonstrates that closure of the open-cell lattice structure enhances the mechanical properties without affecting the functional requirements. Thermoplastic polyurethane (TPU) is used to produce the structures via additive manufacturing (AM) using fused filament fabrication (FFF). Uniaxial compression tests are performed to understand the mechanical and functional properties of the structures. Numerical models are developed adopting an advanced material model aimed at st...

Introduction. Gray cast iron is traditionally used in many industries because it is characterized... more Introduction. Gray cast iron is traditionally used in many industries because it is characterized by flexibility of use, excellent castability, low cost, wide range of achievable mechanical properties [1]. The Italian company Casappa SpA that produces gear pumps for the hydraulic power industry gave the motivation of this study. The company extensively uses pearlitic gray cast iron to manufacture pump bodies of complex three-dimensional shape that are subjected to dynamic service loading conditions. Product reliability requirements have motivated the development of efficient

The techniques of dynamic identification of structural characteristics of buildings are successfu... more The techniques of dynamic identification of structural characteristics of buildings are successfully employed since many years. On new constructions these techniques permit the study of the building response to lowor high-energy vibrations (i.e. to earthquakes) for a safe design, while on ancient/historical buildings they can be employed to monitor the healthiness of the construction i.e. detect any damage repeating the tests during some years. In this work we present an innovative vibrodyne we have designed with the aim of produce a bi-directional excitation harmonic force controlled in amplitude and frequency. This machine is portable, economic, and is suitable for the use into ancient or delicate buildings. In this work we present the preliminary results of a series of tests carried out on an ancient and vast castle undergone to a very elaborated structural investigation. A very interesting comparison between mechanical vibrodyne excitation vs. traditional impact hammer excitatio...

Shock and Vibration, 2017

Materials, 2021

Nowadays, fused deposition modeling additive technology is becoming more and more popular in part... more Nowadays, fused deposition modeling additive technology is becoming more and more popular in parts manufacturing due to its ability to reproduce complex geometries with many different thermoplastic materials, such as the TPU. On the other hand, objects obtained through this technology are mainly used for prototyping activities. For this reason, analyzing the functional behavior of FDM parts is still a topic of great interest. Many studies are conducted to broaden the spectrum of materials used to ensure an ever-increasing use of FDM in various production scenarios. In this study, the effects of several phenomena that influence the mechanical properties of printed lattice structures additively obtained by FDM are evaluated. Three different configurations of lattice structures with designs developed from unit cells were analyzed both experimentally and numerically. As the main result of the study, several parameters of the FDM process and their correlation were identified as possible ...

Material Design & Processing Communications, 2021

Procedia Structural Integrity, 2019

Shape-adaptive or morphing capability is regarded as significant to increase aerodynamic performa... more Shape-adaptive or morphing capability is regarded as significant to increase aerodynamic performance of airfoils employed in aerospace, wind turbines or race cars, while at the same time reducing the number of moving parts. The inherent bistable behavior of asymmetric cross-ply composites makes them as a suitable candidate for morphing applications with a small energy input, and an efficient way to switch between the two equilibrium configurations is given by embedded shape memory alloy (SMA) wires. However, when a bi-stable composite plate is integrated with SMA wires (Shape Memory Alloy Composite, SMAC), the identification of design parameters, namely laminate size and layup, composite elastic constants, SMA wires number and thermomechanical behavior, SMAC manufacturing cycle, is not straightforward. The present work described the strategies developed by the authors to model and optimize a SMAC subjected to bi-stability and post-manufacturing deflection requirements.

Procedia Structural Integrity, 2019

The purpose of this work is to evaluate the influence of co-lamination vs. co-bonding on the fail... more The purpose of this work is to evaluate the influence of co-lamination vs. co-bonding on the failure behavior, and namely the fracture toughness, of carbon fibre reinforced (CFR) composite laminate joints in order to assess comparatively their performance. Since the strength of the laminate and ply texture are parameters affecting the strength of the joint, the comparison is extended to two different types of CFR pre-preg fibers, a satin T1100 with 2573 Nanoalloy® epoxy resin supplied by Toray and a twill T700 with ER450 toughened epoxy resin supplied by CIT, Toray group, representative of two different fields of application, racing and automotive, respectively.

Frattura ed Integrità Strutturale, 2010

Materials, 2019

Shape-adaptive or morphing capability in both aerospace structures and wind turbine blade design ... more Shape-adaptive or morphing capability in both aerospace structures and wind turbine blade design is regarded as significant to increase aerodynamic performance and simplify mechanisms by reducing the number of moving parts. The underlying bistable behavior of asymmetric cross-ply composites makes them a suitable candidate for morphing applications. To date, various theoretical and experiential studies have been carried out to understand and predict the bistable behavior of asymmetric laminates and especially the curvature obtained in their stable configurations. However, when the bi-stable composite plate is integrated with shape memory alloy wires to control the curvature and to snap from a stable configuration to the other (shape memory alloy composite, SMAC), the identification of the design parameters, namely laminate edge length, ply thickness and ply orientation, is not straightforward. The aim of this article is to present the formulation of an optimization problem for the pa...

Fatigue & Fracture of Engineering Materials & Structures, 2017

generation algorithm available in the numerical code. To speed-up the analyses no check of the si... more generation algorithm available in the numerical code. To speed-up the analyses no check of the size and no check of the difference between the lengths of adjacent edges of an element are required; indeed, approximations are all included in the scatter band of the PSM. The following new part has been added to the revised manuscript to clarify this point: "The finite element size d has been intentionally taken as the 'global element size' input by the FE analyst before running the free mesh generation algorithm available in the FE code. Obviously, the edge lengths of the actually generated finite elements will fulfil the prescribed size d only approximately. Nevertheless, the average FE size d has been adopted in Eqs (3) and (4), the effects of the variability of the FE size in the vicinity of the V-notch tip being included in the scatter band of K FE * and K FE ** ." 3. Section 4.2 describes the loading in the shear case, mentioning prescribed displacements which correspond to a gross shear stress. The relation applies to an absent crack. But doesn't a crack weaken the plate so that this relation changes is such a case? Please clarify. Yes, the crack alters the uniform gross shear stress existing in the un-cracked case. In the crack case it is just a reference stress: please note that the same reference stress has been adopted to evaluate the exact SIF K 2 (using extremely refined FE meshes) and the sliding FE peak stress τ ΙΙ,peak (using coarse meshes according to the PSM). The exact SIF K 2 and the sliding peak stress τ ΙΙ,peak evaluated by using the same loading condition are input in Eq. (6) in order to calculate the normalised SIF K FE **. This has been clarified in the section 5.2 of the revised manuscript. 4. In Section 7.4 it is mentioned that the default options are highlighted in Tables 8 and 9 (also in the table captions). Do you mean 'default options indicated'? Thanks. Yes, we mean the 'default options indicated', we have modified both text and Table captions accordingly.

International Journal of Architectural Heritage, 2019

Tie-rods are essential structural elements, which have been employed for centuries in masonry his... more Tie-rods are essential structural elements, which have been employed for centuries in masonry historical buildings, either during the construction or in successive strengthening interventions, with the aim of containing dangerous horizontal actions. The actual work conditions of these tie-rods, which are strongly influenced by their load history, are difficult to be quantified theoretically, and an effective method for their measure is of great importance in order to ensure the efficiency of these elements during the time and the stability of the entire building. Common measurements are often carried out adopting models based upon significant simplifications, like, for example, hinges at the extremities. These assumptions, rarely represent the real work conditions for anchorages. In this work, a non-destructive testing method is presented, based upon sophisticated dynamical models that can take into consideration many of the circumstances neglected by the simplified models. Four case studies are extensively described, trying to embrace the most common situations in term of peculiar features of the building, structural configuration, and load history. The discussion of the results yields the safety margin of the rod with respect to the material failure and provides important indications about the overall stability of the whole building.

Archive of Applied Mechanics, 2017

Two cases of plane-parallel motion of a rigid body with flat basement over a horizontal plane wit... more Two cases of plane-parallel motion of a rigid body with flat basement over a horizontal plane with dry friction are considered. Conditions for the friction impact are obtained for a body performing gliding motion with spinning. For motion of a body in a vertical plane, collisions of the body with the supporting plane are considered. In the parameter space, a map of areas is constructed where the after-collision state of motion is similar.

Materials Today: Proceedings, 2017

This paper presents an experimental and numerical study of vibrations of loudspeakers. The experi... more This paper presents an experimental and numerical study of vibrations of loudspeakers. The experimental part consisted of measuring vibrational responses of cones of the loudspeakers to the sine sweep excitation signal. Acquisition was performed by means of a laser vibrometer. The numerical analysis employed finite element simulations of the cone and suspensions, based on estimation of viscoelastic properties for loudspeaker components. Having acquired accelerations of hundreds of points on the radiating surface, the radiated sound pressure level at one-meter distance has been computed. Confronting SPLs obtained from the two approaches the authors attempted to match the numerical model with the experiment. The matching was confirmed by the comparison between the simulated and measured operational deflection shapes.

Shock and Vibration, 2017

This paper presents an application of vibration analysis to the monitoring of tie-rods. An algori... more This paper presents an application of vibration analysis to the monitoring of tie-rods. An algorithm for the axial load estimation based on experimentally measured natural frequencies is introduced and its application to a case study is reported. The proposed model of a tie-rod incorporates elastic bed-type boundary conditions that represent the contact between stonework and the tie-rod. The weighed differences between experimentally and numerically determined frequencies are minimized with respect to the parameters of the model, the main being the axial load and the stiffness at the tie-rod/wall interface. Thus, the multidimensional optimization problem is solved. Results are analysed in comparison to a model with simple fixed-end boundary conditions. In addition, the analytical formulation of the problem is delivered.

Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering, 2015

Interactions between buildings and earthquakes have been studied for a long time, and there is mu... more Interactions between buildings and earthquakes have been studied for a long time, and there is much literature about them. This research deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to control the vibrations; dry friction has also been considered. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method. From this theoretical standpoint, we derive many important analytical or numerical results, providing us the tools suitable for the design of absorbers in practical cases.

Shock and Vibration, 2016

This study deals with the dynamical evolutions exhibited by a simple mechanical model of building... more This study deals with the dynamical evolutions exhibited by a simple mechanical model of building, comprising a parallelepiped standing on a horizontal plane. The main goal is the introduction of a pendulum in order to reduce oscillations. The theoretical part of the work consists of a Lagrange formulation and Galerkin approximation method, and dry friction has also been considered. From the analytical/numerical simulations, we derive some important conclusions, providing us with the tools suitable for the design of absorbers in practical cases.

Conference Proceedings of the Society for Experimental Mechanics Series, 2011

Anyone can freely access the full text of works made available as "Open Access". Works made avail... more Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law.

Key Engineering Materials, 2007

In this work the fatigue crack growth properties of friction stir welded butt joints are evaluate... more In this work the fatigue crack growth properties of friction stir welded butt joints are evaluated. Fatigue Crack Growth (FCG) tests have been carried out on two particle-reinforced aluminium alloys (AA6061/Al2O3/20p and AA7005/Al2O3/10p). FCG properties have been evaluated at the centre and at the side of the weld, respectively. The results are compared with FCG properties of base materials. The role of alumina in particles inside the matrix is evident in the threshold region: this can be explained in terms of Roughness Induced Crack Closure.