Publications by John Botsis | EPFL Graph Search

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Fiber reinforced polymers (FRPs) subjected to mode I fracture show important toughening due to the development of large scale bridging (LSB). Experimental studies of this phenomenon in unidirectional carbon/epoxy laminates using double cantilever beam spec ...

The periodontal ligament (PDL) functions both in tension and in compression. The presence of an extensive vascular network inside the tissue suggests a significant contribution of the fluid phase to the mechanical response. This study examined the load res ...

An optical fiber Bragg grating (FBG) embedded in an epoxy matrix is indubitably subjected to non-negligible residual stresses arising from the cure, especially for a strong fiber-matrix interface. The spectral response of the FBG sensor is clearly influenced by the presence of the residual non-homogeneous strain field along the grating and results in a distortion (chirp) of the reflected spectrum. Direct applications for distributed strain sensing, without tracking the residual field into account, can lead

The increasing needs of extending the lifetime in high-technology fields, such as space and aerospace, rail transport and naval systems, require quality enhancing of the composite materials either from a processing standing point or in the sense of resista ...

The effects of particle reinforcement of Sn-4.0wt.%Ag-0.5wt.%Cu (SAC405) lead-free solder on interfacial intermetallic layer growth and strength of the ensuing joints through short-term isothermal aging (150 degrees C) were studied. Composite solders were ...

The adhesive bonding of composite materials can be applied to assemble light-weight structures for aeronautical applications. However, the application of adhesive bonds in primary load-bearing structures is limited by the lack of adequate techniques to mon ...

The uncertainty of the crack tip position inside composite coupons during a delamination test under variable fracture mode conditions reduces the accuracy of the experimental results. In this work a method is presented where the crack tip position is locat ...

A partially embedded long fibre-Bragg grating (FBG) into an epoxy cylindrical specimen is used to monitor the strain distribution evolution along its axis when subjected to subsequent cycles of thermal ageing at 70 and 110 degrees C. Assuming a total volum ...

The current study proposes a combined experimental and modeling approach to characterize the mechanical response of composite lead-free solders. The influence of the reinforcement volume fraction on the shear response of the solder material in the joint is assessed. A novel optimized geometry for single lap shear specimens is proposed. This design minimizes the effect of plastic strain localization, leading to a significant improvement of the quality of experimental data. The constitutive model of the solde

Bridging by intact fibers in composite materials is one of the most important toughening mechanisms. However, a direct experimental assessment of its contribution is not easy to achieve. In this work a semi-experimental method is proposed to quantify its c ...

Due to the high homologous temperature and fast cooling rates, the microstructures of SnAgCu (SAC) solders are in a meta-stable state in most applications, which is the cause of significant microstructural evolution and continuous variation in the mechanic ...

Long term durability of osseointegrated implants depends on bone adaptation to stress and strain occurring in proximity of the prosthesis. Mechanical overloading, as well as disuse, may reduce the stability of implants by provoking bone resorption. However ...

Traction-separation relations due to large scale bridging in composites are very important in modeling their fracture response. Several works demonstrated that such relations are dependent upon the specimen's stiffness and loading conditions. Experimental ...

For the detection of problems like fastening failures and delamination in composites, the employment of embedded fiber Bragg grating (FBG) sensors is considered an effective tool to measure non-homogeneous internal strains near damage or interfaces of diss ...

Interfacial debonding is one of the most critical damage modes that threatens the structural performance of sandwich composites. In this work, integrated multiplexed fiber Bragg grating (FBG) sensors of 1 mm gauge length are used for detection and characte ...

Thin-ply composites are rapidly gaining interest in the composite industry, not only because of the larger design possibilities that they offer, but also because of positive size effects that have been shown to improve performance in various loading condit ...

The hydrothermal ageing of glass/epoxy interface is investigated using an experimental numerical approach on cylindrical epoxy specimens with centrally located optical fibers. A 24 mm long Bragg grating sensor is inscribed on the optical fiber and used to ...

Objectives(i) To assess the effects of mechanical overloading on implant integration in rat tibiae, and (ii) to numerically predict peri-implant bone adaptation. Materials and methodsTranscutaneous titanium implants were simultaneously placed into both tib ...

This study presents and validates a set of automated techniques for tracking crack propagation in adhesively bonded composite joints using Digital Image Correlation (DIC). Two approaches were developed: one based on vertical displacement thresholds and another on localized strain fields. The methods are fully automated from the initial crack length identification stage, using a region-growing segmentation algorithm, and are validated under both quasi-static and fatigue loading for joints with different adhe

In microelectronics applications, SnAgCu lead-free solder joints play the important role of ensuring both the mechanical and electrical integrity of the components. In such applications, the SnAgCu joints are subjected to elevated homologous temperatures f ...

John Botsis

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Micromechanical study on the origin of fiber bridging under interlaminar and intralaminar mode I failure

Load Response of Periodontal Ligament: Assessment of Fluid Flow, Compressibility, and Effect of Pore Pressure

Modeling of the residual stresses acting on a low-birefringence fiber Bragg grating sensor embeded in an epoxy matrix

On the degree of conversion and coefficient of thermal expansion of a single fiber composite using a FBG sensor

Interfacial intermetallic growth and strength of composite lead-free solder alloy through isothermal aging

Monitoring strain gradients in adhesive composite joints by embedded fiber Bragg grating sensors

Crack tip identification with long FBG sensors in mixed-mode delamination

Monitoring of process induced strains in a single fibre composite using FBG sensor: A methodological study

A Study of the Shear Response of a Lead-Free Composite Solder by Experimental and Homogenization Techniques

Studies of mode I delamination in monotonic and fatigue loading using FBG wavelength multiplexing and numerical analysis

Isothermal Ageing of SnAgCu Solder Alloys: Three-Dimensional Morphometry Analysis of Microstructural Evolution and Its Effects on Mechanical Response

Numerical prediction of peri-implant bone adaptation: Comparison of mechanical stimuli and sensitivity to modeling parameters

Towards a geometry independent traction-separation and angle relation due to large scale bridging in DCB configuration

Monitoring of non-homogeneous strains in composites with embedded wavelength multiplexed fiber Bragg gratings: A methodological study

Monitoring and characterization of the interfacial fracture in sandwich composites with embedded multiplexed optical sensors

Thin ply composites: Experimental characterization and modeling of size-effects

Studies of hygrothermal degradation of a single fiber composite: An iterative approach with embedded optical sensors and numerical analysis

Peri-implant bone adaptations to overloading in rat tibiae: experimental investigations and numerical predictions

Automated crack propagation detection in adhesively bonded composite joints with Digital Image Correlation techniques

Multi-scale modeling of elasto-plastic response of SnAgCu lead-free solder alloys at different ageing conditions: Effect of microstructure evolution, particle size effects and interfacial failure