Kamarul Ariffin Zakaria

Fatigue Damage Assessment of the Engine Mount Bracket Using a Statistical Based Approach

Fatigue damage assessment is very important in design process of the component to determine their durability under service loading conditions. In service, the great majority of structures and components are subjected to stress of variable amplitude loading. The purpose of this research is to analyse statistically of two types of strain signals from road loading and compare their effect on fatigue damage of the engine mount bracket. Strain gauges were attached to the engine mount bracket and were connected to the data acquisition set in order to capture the actual strain signals when an automobile was driven on two different road surfaces. The strain signals were then analysed using global signal statistic and integrated kurtosis based algorithm for Z-filter (I-kaz) method. Meanwhile, damage of the engine mount bracket was evaluated using finite element commercial software. From the analysis, it was found that the fatigue damage showed an increment with the respective statistical values of the strain signals.

Investigation on the fatigue life characteristic of kenaf/glass woven-ply reinforced metal sandwich materials

Fatigue life characteristic of hybrid composite reinforced metal laminate is a notable investigation since this kind of material offers several superior characteristics over conventional metallic alloy. A majority of the researches have focused on the mechanical properties of hybrid composite and conventional fibre metal laminate such as glass reinforced aluminium epoxy and aramid fibre reinforced aluminium laminate. However, investigation on the fatigue life behaviour of hybrid composite reinforced metal laminate still remains unexplored. In this study, the fatigue life characteristic of hybrid kenaf/glass reinforced metal laminate with different fibre configurations, orientation and stress ratio was presented. Fibre metal laminate was manufactured through hot press moulding compression method using annealed aluminium 5052 as the skin layers and the composite laminate as the core constituent. Tensile test was conducted at a quasi-static rate in accordance with ASTM E8 while tension–tension fatigue test was conducted at force controlled constant amplitude according to ASTM E466. Experimental results revealed that fibre metal laminate with 0°/90° fibre orientation exhibited better tensile and fatigue properties compared to fibre metal laminate with ±45° fibre orientation regardless of the woven-ply fibre configurations. Besides that, it was identified that higher stress ratio improves the fatigue life cycle of the fibre metal laminate structures.

Correlation of Impact Energy from Instrumented Charpy Impact

This paper proposes the correlation of absorbed energy with calculated energy using the power spectrum density (PSD) method. The total absorbed energy was obtained using the dial/encoder system may significantly vary depending on the strength and ductility of the material. In addition, according to ASTM E23, over 80% of absorbed energy is inaccurate and approximate. For this reason, we determined the energy collected from the dial/encoder Charpy impact test using the signal processing approach. Strain gauges were connected to the Charpy impact striker and the high frequency data acquisition system in order to capture the dynamic impact strain response. Specimens of an aluminium alloy of 6061-T6 and carbon steel 1050 with different velocities and thicknesses were used in the experiment. The specimens are prepared based on the ASTM E23. A collection of signal was converted from the time domain to the frequency domain by means of PSD method and the area under its plot was used to calculate strain energy. The comparison between energy absorbed during the experiment with PSD peak and the strain energy were performed using different materials, velocities and thicknesses. The total energy absorbed for both material with the PSD peak and the strain energy using the dial/encoder system can be linked by a power law equation with R2 96% and R2 94 %. Thus, the effects of the strain signal pattern and impact duration with different parameters were correlated with the PSD peak and the strain energy. This correlation using PSD can be used as an alternative for the charpy impact test and solve the problem of inaccurate absorbed energy.

Observation of the Fatigue Crack Propagation Rate of an Aluminum Alloy Specimen under Fatigue Spectrum Loadings

Abstract This paper presents an assessment on fatigue crack propagation (FCG) behaviour and fractography observation of an aluminum alloy that was exposed under spectrum loadings. The FCG test has three types of cyclic loadings, namely, constant-amplitude loading (CAL) as well as high-to-low and low-to-high sequence loadings. All three have been performed with the Al6061-T6 specimens. The tests were performed using a 100 kN servo-hydraulic fatigue testing machine according to ASTM E647 standard. The results show that fatigue crack propagation and its fractography were influenced by the load interaction and the sequence, which affect the fracture behaviour of aluminum alloys. The fracture surface exhibited irregular local striation spacings under the spectrum loading. Moreover, the micrographs show increased plasticity throughout the crack propagation compared to CAL.

Experimental Analysis of an Instrumented Charpy Impact Using Signal Processing Approach

The dynamic responses of the standard charpy impact machine are experimentally studied using the relevant data acquisition system in order to obtain the impact response. For this reason, strain gauges were connected to the data acquisition set and it was then attached to the charpy striker for the signal collection. Aluminium 6061 and low carbon steel 1050 were used for extracting strain responses on the striker during the testing. In this work, the power spectrum density (PSD) approach was then used for the energy based observation and a signal was converted from the time domain to the frequency domain using the fast Fourier transform (FFT) method. Comparison between experimental findings with related parameters such as of different materials, strain signals pattern, I-kaz, were finally correlated and discussed. It was found that the modulus of elasticity were proportional to the energy absorbed, strain signals amplitude and PSD. Finally, it is suggested that the properties of materials and the impact signals pattern is suitable to be analysed using the signal processing approach.