Eco-hybrid Composite Failure Behavior of Two Serial Bolted Joint Holes

This study investigates the geometrical effect of two serial bolted joint holes on hybrid composites. Geometry parameters studied were edge distance-to-upper hole centre (E/D) and the distance between centers of two holes diameter (K/D). The hybrid composites were fabricated using kenaf woven fiber and E-glass woven fiber. Composite specimens were manufactured through hot press molding compression method at 180oC. The bearing test was conducted according to ASTM D-5961 ‘Procedure C’. The results show bearing strength and failure mechanisms of hybrid composites highly depend on the geometry parameters. Hybrid composites with the highest geometrical parameter, K/D = 5 and E/D = 4, show the highest bearing strength (32.381 MPa) while hybrid composites with the lowest geometrical parameter, K/D = 2 and E/D = 2, exhibit the lowest bearing strength (20.445 MPa). Therefore, this indicates that bearing strength increases with increase of K/D and E/D ratio. The failure behaviors observed were shear-out modes, bearing modes and net-tension modes

Investigation on fatigue life behaviour of sustainable bio-based fibre metal laminate / D. Sivakumar...[et al.]

Fibre-Metal Laminate (FML) is a hybrid structure which offers various advantages over conventional material. It had been used in automotive and aircraft sector since many years ago due to its lightweight and low cost properties. Previous study had shown FML had excellent fatigue crack resistance characteristic compared to metallic alloy. This study shows the effects of different composition of oil palm empty fruit bunch (OPEFB) fibre on the fatigue life behaviour, hardness properties and mass of FML. FML was manufactured based on randomly oriented short OPEFB fibre and annealed aluminium alloy 6061. The FML panels were formed by bonding aluminium layers to composite by using the hot press compression moulding method with picture frame mould. Static test was conducted prior to fatigue test at quasi-static manner. The fatigue life of monolithic aluminium was investigated and set as a benchmark. The fatigue test was conducted at load levels of 80 to 95% of ultimate tensile strength using Universal Testing Machine. Results suggest that FML with 30% fibre loading had the highest fatigue resistance compared to other fibre composition. The mass of FML had been identified less than aluminium up to 30%. The hardness strength increases with increase fibre composition for composite while the hardness strength is relatively constant for FML

Failure analysis of hybrid fibre reinforced plastics for bolted joint under thermal effect / D. Sivakumar...[et al.]

Composite material is gaining a large attention in these few years due to its high strength to weight ratio. The cost of composite is also relatively lower than conventional metallic alloy. Several previous studies had shown introducing of synthetic fibre in the natural fibre-based composite polymer can enhance the mechanical strength of the composite structure. This research paper studies the effect of temperature and preload moment on the bearing strength of woven kenaf-glass fibre reinforced polypropylene hybrid composite. The kenaf fibre and E-glass fibre are in the form of plain weave fabric. Composite specimens were manufactured through hot press moulding compression method at 180ºC. In bolted joint test, specimens were exposed to a temperature of 25ºC (room temperature), 40ºC, 50ºC, and 60ºC and tightened with 0Nm, 5.2Nm and 7.5Nm preload moment. Bearing response under different conditions was tested according to ASTM D5961 standard procedure and failure modes were observed. The results revealed that increase in the ambient temperature reduced the bolted joint strength whereas the increase in preload moment improved the joint strength

Ultrasonic monitoring of compressive damage evolution in concrete

This paper presents the outcomes of an experimental study conducted on a short concrete column loaded to failure under uniaxial compression. Piezoceramic transducers bonded to the free surfaces of the specimen were used for ultrasonic inspection during the progressive loading. The evolution of damage was monitored by means of change in ultrasonic wave velocity and scaling subtraction method, with the aim to highlight the capabilities and limitations of these approaches. The results show that the change in the nonlinear parameter derived by the scaling subtraction method is over two orders of magnitude greater than the relative change in the Rayleigh wave speed, thereby indicating the much greater sensitivity of the nonlinear ultrasonics approach for damage detection.Aditya Khanna, Andrei Kotousov, Ching-Tai Ng and L. R. Francis Ros

Implication of changing loading conditions on structural health monitoring utilising guided waves

Structural health monitoring systems based on guided waves typically utilise a network of embedded or permanently attached sensors, allowing for the continuous detection of damage remote from a sensor location. The presence of damage is often diagnosed by analysing the residual signals from the structure after subtracting damage-free reference data. However, variations in environmental and operational conditions such as temperature, humidity, applied or thermally-induced stresses affect the measured residuals. A previously developed acoustoelastic formulation is here extended and employed as the basis for a simplified analytical model to estimate the effect of applied or thermally-induced stresses on the propagation characteristics of the fundamental Lamb wave modes. It is noted that there are special combinations of frequency, biaxial stress ratio and direction of wave propagation for which there is no change in the phase velocity of the fundamental anti-symmetric mode. The implication of these results in devising effective strategies to mitigate the effect of stress induced variations in guided-wave damage diagnostics is briefly discussed.Munawwar Mohabuth, Andrei Kotousov, Ching-Tai Ng and LR Francis Ros

Evaluating the health-related quality of life of the rare disease population in Hong Kong using EQ-5D 3-level

Objectives This study aimed to establish a normative profile of health-related quality of life (HRQOL) of the rare disease (RD) population in Hong Kong (HK) and identify potential predictors. Methods Between March 2020 and October 2020, patients with RD and caregivers were recruited through Rare Disease Hong Kong, the largest RD patient group alliance in HK. HRQOL was derived using the EQ-5D 3-Level with reference to the established HK value set. Utility scores were stratified according to demographics and disease-related information. Multiple linear regression was performed to explore the associations between patient characteristics and HRQOL. Results A total of 286 patients, covering 107 unique RDs, reported a mean utility score of 0.53 (SD 0.36). Thirty patients (10.5%) reported negative utility scores, indicating worse-than-death health states. More problems were recorded in the “usual activities” and “self-care” dimensions. Univariate analyses revealed that neurologic diseases, high out-of-pocket expenditure, home modification, and living in public housing or subdivided flats/units were significantly associated with lower HRQOL. A total of 99 caregivers reported a mean utility score of 0.78 (SD 0.17), which was significantly associated with the utility score of patients they took care of (r = 0.32; P = .001). Conclusions The normative profile of the RD population was established, which revealed lower HRQOL in the RD population than other chronic disease groups and general population in HK. Findings were corroborated by evidence from other cohorts using EQ-5D, combined as part of a meta-analysis. Identifying predictors highlight areas that should be prioritized to improve HRQOL of RD population through clinical and psychosocial dimensions

Client Service Receipt Inventory as a standardised tool for measurement of socio-economic costs in the rare genetic disease population (CSRI-Ra)

The measurement of costs is fundamental in healthcare decision-making, but it is often challenging. In particular, standardised methods have not been developed in the rare genetic disease population. A reliable and valid tool is critical for research to be locally meaningful yet internationally comparable. Herein, we sought to develop, contextualise, translate, and validate the Client Service Receipt Inventory for the RAre disease population (CSRI-Ra) to be used in cost-of-illness studies and economic evaluations for healthcare planning. Through expert panel discussions and focus group meetings involving 17 rare disease patients, carers, and healthcare and social care professionals from Hong Kong, we have developed the CSRI-Ra. Rounds of forward and backward translations were performed by bilingual researchers, and face validity and semantic equivalence were achieved through interviews and telephone communications with focus group participants and an additional of 13 healthcare professional and university students. Intra-class correlation coefficient (ICC) was used to assess criterion validity between CSRI-Ra and electronic patient record in a sample of 94 rare disease patients and carers, with overall ICC being 0.69 (95% CI 0.56–0.78), indicating moderate to good agreement. Following rounds of revision in the development, contextualisation, translation, and validation stages, the CSRI-Ra is ready for use in empirical research. The CSRI-Ra provides a sufficiently standardised yet adaptable method for collecting socio-economic data related to rare genetic diseases. This is important for near-term and long-term monitoring of the resource consequences of rare diseases, and it provides a tool for use in economic evaluations in the future, thereby helping to inform planning for efficient and effective healthcare. Adaptation of the CSRI-Ra to other populations would facilitate international research

Theta angle versus CP violation in the leptonic sector

Assuming that the axion mechanism of solving the strong CP problem does not exist and the vanishing of theta at tree level is achieved by some model-building means, we study the naturalness of having large CP-violating sources in the leptonic sector. We consider the radiative mechanisms which transfer a possibly large CP-violating phase in the leptonic sector to the theta parameter. It is found that large theta cannot be induced in the models with one Higgs doublet as at least three loops are required in this case. In the models with two or more Higgs doublets the dominant source of theta is the phases in the scalar potential, induced by CP violation in leptonic sector. Thus, in the MSSM framework the imaginary part of the trilinear soft-breaking parameter A_l generates the corrections to the theta angle already at one loop. These corrections are large, excluding the possibility of large phases, unless the universality in the slepton sector is strongly violated.Comment: 5 pages, 2 figure