Mohd Faridz Mod Yunoh

Targeted delivery of lovastatin and tocotrienol to fracture site promotes fracture healing in osteoporosis model: micro-computed tomography and biomechanical evaluation.

Osteoporosis is becoming a major health problem that is associated with increased fracture risk. Previous studies have shown that osteoporosis could delay fracture healing. Although there are potential agents available to promote fracture healing of osteoporotic bone such as statins and tocotrienol, studies on direct delivery of these agents to the fracture site are limited. This study was designed to investigate the effects of two potential agents, lovastatin and tocotrienol using targeted drug delivery system on fracture healing of postmenopausal osteoporosis rats. The fracture healing was evaluated using micro CT and biomechanical parameters. Forty-eight Sprague-Dawley female rats were divided into 6 groups. The first group was sham-operated (SO), while the others were ovariectomized (OVx). After two months, the right tibiae of all rats were fractured at metaphysis region using pulsed ultrasound and were fixed with plates and screws. The SO and OVxC groups were given two single injections of lovastatin and tocotrienol carriers. The estrogen group (OVx+EST) was given daily oral gavages of Premarin (64.5 µg/kg). The Lovastatin treatment group (OVx+Lov) was given a single injection of 750 µg/kg lovastatin particles. The tocotrienol group (OVx+TT) was given a single injection of 60 mg/kg tocotrienol particles. The combination treatment group (OVx+Lov+TT) was given two single injections of 750 µg/kg lovastatin particles and 60 mg/kg tocotrienol particles. After 4 weeks of treatment, the fractured tibiae were dissected out for micro-CT and biomechanical assessments. The combined treatment group (OVx+Lov+TT) showed significantly higher callus volume and callus strength than the OVxC group (p<0.05). Both the OVx+Lov and OVx+TT groups showed significantly higher callus strength than the OVxC group (p<0.05), but not for callus volume. In conclusion, combined lovastatin and tocotrienol may promote better fracture healing of osteoporotic bone.

FAILURE ANALYSIS OF A SEMICONDUCTOR PACKAGING LEADFRAME USING THE SIGNAL PROCESSING APPROACH

This paper presents a durability analysis of two types of copper leadframe, i.e. the un-oxidised leadframe and the oxidised leadframe. Both leadframe types were used in the fabrication process of a Quad Flat No-Lead (QFN) package, which can be said as a recent type of the 3D stacked die semiconductor package. This study involved the durability test and analysis on QFN packages when these packages were subjected under constant cyclic loadings. In order to perform the cyclic test, the procedure of the three-point cyclic bending test has been employed on the packages. In addition, a strain gauge which was connected to the dynamic data acquisition system was used for each tested QFN package for determining the response of the captured cyclic strain signal. It has been found that the variable amplitude pattern of signal response has been obtained during the constant cyclic test. The obtained response signals for both type of leadframe were then analysed using the approaches of signal processing technique, which is relatively new in this field. The collected response signal were analysed using the normal statistical methods, the Power Spectrum Density (PSD) calculation and also the time-frequency localization analysis. From the detail signal analysis, it has been found that the un-oxidised leadframe showed a lower range of strain response compared to the oxidised leadframe, indicating higher lifetime. As a result, this finding lead to the durability conclusion, for which the un-oxidised leadframe has more durability effects and it also has higher lifetime compared to the oxidised leadframe. Finally, a micro-crack phenomenon at the epoxy interface between the die and the leadframe was also observed for the QFN package with the oxidised leadframe.

Hardness Test on an Epoxy Mold Compounds of a Quad Flat No Lead Package Using the Depth Sensing Nanoindentation

This study focuses on the effect of stress and load towards hardness at epoxy mold compounds (EMCs) of a Quad Flat No- Lead (QFN) package using indentation technique. A series of three points bending cyclic test were performed with four different loads between 60 N to 120 N on QFN package. The nanoindentation with the maximum load of 300 mN was indented at five locations that perpendicular to the stress line on EMCs of QFN package after three points bending cyclic test were performed. The findings showed that the mean value of hardness was varied with load and stress. Higher load and stress were found to be not affected by hardness of EMCs. From the results, it is believed that the applied load and stress not play a role towards the hardness of EMCs. A polynomial relationship was plotted and shown that correlation of coefficient (R2) between stress and hardness of the studied EMCs was found to be at 97%. Finally, the finding suggested that a close correlation between the stress and hardness since it correlation coefficient gave a higher value with the polynomial relationship.

Fatigue time history analysis for determining the strain signal behaviour

This paper presents a fatigue time history analysis for determining the strain signal statistical behaviour using a wavelet and fatigue I–kaz approach. The ability of discrete wavelet transform (DWt) in the study is initiated by the high amplitude events identification and extraction based on wavelet coefficients and energy. Recently, there has been a motivation to explore a new approach by the authors, which led to the introduction of kurtosis–based analysis. An experiment has been performed on the car suspension system (coil spring), and the time history signals were collected based on the road surface in a residential area. Seven high amplitude segments, named H1–H7, were extracted based on DWT (Db4) analysis and analysed using fatigue I–kaz approach, which gave the higher values of the coefficients for DWT (Db4) and fatigue I–kaz at 2.02 × 1010 and 323.96. The discrete energy from the fatigue time history signal influenced the DWT energy coefficients and fatigue I–kaz coefficients.

PROBABILITY ANALYSIS IN DETERMINING THE BEHAVIOUR OF VARIABLE AMPLITUDE STRAIN SIGNAL BASED ON EXTRACTION SEGMENTS

THIS PAPER FOCUSES ON ANALYSIS IN DETERMINING THE BEHAVIOUR OF VARIABLE AMPLITUDE STRAIN SIGNALS BASED ON EXTRACTION OF SEGMENTS. THE CONSTANT LOADING (CAL), THAT WAS USED IN THE LABORATORY TESTS, WAS DESIGNED ACCORDING TO THE VARIABLE AMPLITUDE LOADING (VAL) FROM SOCIETY OF ENGINEER (SAE). THE SAE STRAIN SIGNAL WAS THEN EDITED TO OBTAIN THOSE SEGMENTS THAT CAUSE FATIGUE DAMAGE TO COMPONENTS. THE SEGMENTS WERE THEN SORTED ACCORDING TO THEIR AMPLITUDE AND WERE USED AS A REFERENCE IN THE DESIGN OF THE CAL LOADING FOR THE LABORATORY TESTS. THE STRAIN SIGNALS THAT WERE OBTAINED FROM THE LABORATORY TESTS WERE THEN ANALYSED USING FATIGUE LIFE PREDICTION APPROACH AND STATISTICS, I.E. WEIBULL DISTRIBUTION ANALYSIS. BASED ON THE PLOTS OF THE PROBABILITY DENSITY FUNCTION (PDF), CUMULATIVE DISTRIBUTION FUNCTION (CDF) AND THE PROBABILITY OF FAILURE IN THE WEIBULL DISTRIBUTION ANALYSIS, IT WAS SHOWN THAT MORE THAN 70% FAILURE OCCURRED WHEN THE NUMBER OF CYCLES APPROACHED 1.0 X 1011. THEREFORE, THE WEIBULL DISTRIBUTION ANALYSIS CAN BE USED AS AN ALTERNATIVE TO PREDICT THE FAILURE PROBABILITY.

Determining the Behaviour of Fatigue Strain Histories of Vehicle Coil Springs by Using Statistical Inferences

The evaluation of fatigue behavior of real components under service loading is important in reliability analysis. The present paper investigates the characteristics of two strain signals spectrum by using statistical inferences. The data used in this study are obtained from strain gauges installed on coil spring component of car suspension system driven over two different road surfaces. The coil springs are made of SAE 5160 carbon steel materials. The strain signals are explored to produce the summary statistics (i.e. root-mean-square, kurtosis, skewness etc.) and the rainflow cycle counting is performed to obtain total number of cycles and damage per cycle. Further, distribution fitting is applied to the cycle-counted strain ranges data. The results show that both signals fit well to a mixed Weibull distribution with three subpopulations.

The Morlet and Daubechies Wavelet Transforms for Fatigue Strain Signal Analysis

This paper presents the convenient wavelet family for the fatigue strain signal analysis based on the wavelet coefficients. This study involves the Morlet and Daubechies wavelet coefficients using both the Continuous and Discrete Wavelet Transforms, respectively. The signals were collected from a front lower suspension arm of a passenger car by placing strain gauges at the highest stress locations. The car was driven over public road surfaces, i. e. pavé, highway and UKM roads. In conclusion, the Daubechies wavelet was the convenient wavelet family for the analysis. It was because the wavelet gave the higher wavelet coefficient values indicating that the resemblance between the wavelet and the signals was stronger, closer and more similar.

Durability Analysis of Motorcycle Frame Using Fatigue I-Kaz Technique

This paper presents durability analysis using a new statistical-based method, called the Fatigue Integrated Kurtosis-based Algorithm for Z-notch filter (Fatigue I-kaz) technique. This method provides a three dimensional graphical representation of the data distribution of the signal at three different frequency range in order to measure the degree of data scattering. For validation, three road surfaces were used for data collection purposes. An experiment has been performed on the motorcycle frame. In this study, the strain signals were collected based on three different road surfaces. The strain gauges were fixed on the motorcycle frame to measure the variable strain amplitude loadings imposed. The strain signals were then analysed using Fatigue I-kaz coefficient. Residential road surfaces give a higher Fatigue I-kaz coefficient, f than campus and off road surfaces which is 0.0120 which is 0.0079 and 0.0067

Durability Assessment of Quad Flat No-Lead Package Using Signal Analysis

This paper presents a methodology to determine the durability of Quad Flat No-Lead (QFN) package. The QFN package is useful for improving the reliability of the package. A mechanical fatigue test namely three points bending cyclic test and signal analysis were proposed in this paper. The three points bending cyclic test method is a test assembly that supports a specimen on two anvils or rollers, and symmetrically loads the specimen on the opposite surface with an anvil or roller using micro-tester machine. For strain signal collection, a strain gauge was connected to the dynamic data acquisition system, and it was used for each tested QFN package for determining the response of the captured cyclic strain signal. It was found that the sinusoidal amplitude pattern of signal response has been obtained during the constant three points bending cyclic test. The obtained response signals were then analysed using the Power Spectral Density.

Effect of Hook Location for Ultra Fine Pitch Wirebonding Pull Testing Method

Over the years the methods for checking bonding quality during volume production still remains the same. These inspection methods like ball shear to test the first bond quality and wire pull to test the second bond integrity and quality have proven to be acceptable and achievable for many current industrial needs. However, driven by the relentless pursuit of dimensional reduction in wire bonding technology which calls for reduction in wire diameter, these conventional methods may not be sufficient. The interaction between machine, bonding tools, materials and the different categories of failure modes and mechanism during this quality test has become much more sensitive. The intent of this paper is to study and define the different categories of failure modes during 2nd bond test for ultra fine gold wire from 15 micron diameter up to 50 micron diameter. Therefore, lifted stitch or lifted 2nd bond which is a failure description known to be a ‘reject’ before can be re-visited. Analysis found that the two different test locations revealed that test location B or placing the hook as near possible to the leads where the 2nd bond was bonded is the better method to test the 2nd bond strength and performance as compared to the earlier bond pull method (location A).