Adhesive bonds have very strong influence on mechanical properties of composite particu- late metal foams. This study experimentally investigates for the first time the geometrical and mechanical properties of PA 12 adhesive bonds between spherical advanced pore morphology (APM) elements made of AlSi10 foam. A new experimentation setup for mechanical testing of bonds in APM structures is based on APM element puncturing. The results show that mechanical behaviour of adhesive bonds differs much from the basic mechanical behaviour of adhesive. Two different bond failure modes are identified, depend- ing on the bond geometry. The geometrical and mechanical results are statistically inter- preted for simpler representation, applicability, and modelling of bonds in APM composites.
COBISS.SI-ID: 21338134
This paper presents the results of an experimental work carried out to fabricate and characterise the in-situ foam filled tubes (FFTs) made of aluminium alloys prepared by powder metallurgy method, using aluminium alloy tubes with extremely thin walls (~0.6 mm). The fabrication procedure demonstrates that thin-walled tubes with extremely thin walls can support temperatures near to its melting temperature (~700 °C) required to form a closed-cell aluminium alloy foam, consequently in-situ filling the tube. The mechanical performance of fabricated structures was evaluated using uniaxial compressive tests and infrared thermography. Results demonstrate that the benefits of the manufacturing process and its product, the FFTs (composite structures). Additionally, they reveal that this is a cost-effective solution to prepare efficient energy absorbing lightweight structures, allowing to adjust the weight and levels of the energy absorption, simultaneously. The results demonstrate that the promising in-situ FFTs with thinner outer tubes axially deform in an efficient mixed mode, showing superior energy absorption capability compared to the empty thin-walled tubes.
COBISS.SI-ID: 21215254
Auxetic cellular structures build from inverted tetrapods were experimentally tested at high strain rate com- pression loading for the first time. The strain rates up to 10,000 1/s were achieved with gas powder gun, where the shock deformation mode is predominant. The deformation localizes in the deformation front between the impacting specimen and the fixed plate due to the inertia effects. This deformation mode results in stiffness increases in comparison to the quasi-static response. The results from experimental testing were used for validation of developed computational models in finite element explicit code LS-DYNA. Furthermore, the validated computational models were used for critical strain rate analysis, determination of critical loading velocities and analysis of deformation modes together with analytical constitutive crushing models of cellular structures.
COBISS.SI-ID: 21653270
The considered computational models have the same porosity but different pore topology patterns. Multiaxial loading conditions in the direction perpendicular to the longitudinal axis of pores are assumed to be proportional (in-phase) and non-proportional (out-of-phase) loading paths in numerical simulation. The fatigue life analysis is performed using a damage initiation and evolution law, based on the inelastic strain energy approach. The computational results show that a different fatigue life is obtained in the models with the same porosity but with different pore topology at the same loading level.
COBISS.SI-ID: 19981334
For the purpose of making of a solid body of an electric guitar the acoustic- and mechanical properties of walnut- (Juglans regia L.) and ash wood (Fraxinus excelsior L.) were researched. The acoustic properties were determined by a flexural vibration response mesurement of laboratory conditioned wood elements. The research confirmed better mechanical properties of ash wood, that is, the larger modulus of elasticity and shear modules in all anatomical directions and planes. The acoustic quality of ash wood was better only in the basic vibration mode. Walnut was, on the other hand, lighter and more homogenous and had lower acoustic- and mechanical anisotropy. Additionally, reduced damping of walnut at higher vibration modes is assumed to have a positive impact on the vibration response of future modelled and built solid bodies of electric guitars. When choosing walnut wood, better energy transfer is expected at a similar string playing frequency and a structure resonance of the electric guitar. Determined acoustic and mechanical properties of the wood elements are (meanwhile) beeing compared to the comparable parameters of artifitial elements with cellular structure.
COBISS.SI-ID: 3007113