Finite element modeling of laminated composite plates with locally delaminated interface subjected to impact loading

This paper investigates the effects of localized interface progressive delamination on the behavior of two-layer laminated composite plates when subjected to low velocity impact loading for various fiber orientations. By means of finite element approach, the laminae stiffnesses are constructed independently from their interface, where a well-defined virtually zero-thickness interface element is discreetly adopted for delamination simulation. The present model has the advantage of simulating a localized interfacial condition at arbitrary locations, for various degeneration areas and intensities, under the influence of numerous boundary conditions since the interfacial description is expressed discretely. In comparison, the model shows good agreement with existing results from the literature when modeled in a perfectly bonded state. It is found that as the local delamination area increases, so does the magnitude of the maximum displacement history. Also, as top and bottom fiber orientations deviation increases, both central deflection and energy absorption increase although the relative maximum displacement correspondingly decreases when in contrast to the laminates perfectly bonded state

The effects of the presence of a kitchen house on the wind flow surrounding a low-rise building

Most Malaysian rural houses are categorized as non-engineered buildings and vulnerable to damage during events such as windstorms due to the fact that these houses lack engineering considerations. These houses are characterized by having an attached kitchen house, and many of these houses were previously damaged by thunderstorms. The current research investigated the air flow characteristics changes surrounding these houses as a result of the presence of the kitchen. The roof pitch, position, gap height, and overhang were investigated using computational fluid dynamics (CFD) simulations. The results showed that the kitchen position at the center resulted in a slight increase in the suction on the ridge of the roof; however, it significantly altered the flow pattern in the windward and leeward directions. The results also showed that the roof overhang, roof pitch, and kitchen position contributed severely to the damage of the rural house. Moreover, the highest suction occurred at the roof ridge when the kitchen was located at the center of the rural house (Cp = −2.28). Therefore, the authors believe that it is more advantageous to have a kitchen connected to the core as it reduces the pressure on the roof of the core during thunderstorm events

Development of Site-Specific Wind Hazard Map for Peninsular Malaysia via Spatial Modeling

The commonly used approach to predict and evaluate the wind risk in Peninsular Malaysia is to employ the basic wind speed (Vs) hazard map, which underestimates the real damage due to the limitation of factors considered by the current map. This paper aimed to develop a new wind hazard map for Peninsular Malaysia based on the site wind speed (Vsite) rather than the Vs using the Geographical Information System. The development of the Vsite map considered the effects of the Land Use Land Cover (LULC) and the topography conditions that were not taken into consideration by the Malaysian Standard during the development of the Vs map. The statistical analysis proved that the wind hazard in Peninsular Malaysia is directly proportional to the LULC and inversely proportional to the Hill Shape Multiplier. In addition, the results showed that the existing Vs map underrated the wind hazard in Peninsular Malaysia by almost 9.02% to 17.79% compared to the developed Vsite map. Therefore, the use of the newly developed map to evaluate the wind hazards will significantly enhance the assessment, and the new map has the potential to be incorporated into the Malaysian Standard for this purpose

Finite element modeling of laminated composite plates with locally delaminated interface subjected to impact loading

This project report presents the finite element formulation for the investigation of the effects of interface imperfection on the impact behavior of a laminated composite plate. The interface condition between the laminas plays a very important role in the determination of the behavior of the composite laminates. If the bonding is imperfect, it has high possibility to delaminate progressively. Most of the previous studies on laminated composites were carried out adopting the assumption that the laminas are perfectly bonded. However, the existence of a perfect interfacial bond in a real laminated composite seems to be impossible. Therefore, this study aims to investigate the effect of localized interface imperfection on the behavior of a laminated composite plate when subjected to low velocity impact loading for various fiber orientations. A thin, flat, rectangular laminated plate with two layers of Eglass/ Epoxy transversely isotropic lamina and an orthotropic interface layer between them are considered in this study. The interface is modeled as a layer of zero thickness and zero mass, and the imperfection factor is applied locally to the interface. By using MATLAB, the stiffness matrix, mass matrix, and the impact force vector are formulated and programmed in order to obtain the deformation of the plate. The results show that as the separation of fiber orientation between the two laminas increases, both central deflection and energy absorption increase. The increase of delamination area leads to plate’s damage due to the increase in the absorbed energy, resulting in higher deformation

Cracking behavior of sea sand RC beam bonded externally with CFRP Plate

CFRP is an alternative technique for cracking control of high-chloride reinforced concrete (RC) beams. This research, therefore, investigates the strength performance and failure mode and cracking behaviour of RC beams incorporated with sea sand bonded externally with the carbon fibre reinforced polymer (CFRP) plate. Sea sand is used as a 100% replacement of fine aggregate. Three batches of RC beams were carried out in this research, including the control beam (no sea sand neither CFRP), RC beam with normal sand bonded with CFRP plate, and RC beam with sea sand and bonded with CFRP. A four-point bending test was performed under static loading for the specimens. Finite element simulation was modelled for further comparison. The experimental findings showed that the flexural capacity of the sea sand RC beam bonded externally with CFRP plate is 5.50% greater than the flexural strength of the beam without CFRP (control beam). Besides, results demonstrated that RC beams bonded externally with CFRP were failed by plate end debonding (PED) while the control RC beam without bonding was failed at the mid-span by concrete crushing. However, the bonded RC beams were stiffer, which could lead to lower crack spacing. Finite element simulation showed very acceptable results compared to the experimental results

The Use of Calcium Lactate to Enhance the Durability and Engineering Properties of Bioconcrete

This study investigated the optimization of the bioconcrete engineering properties and durability as a response of the calcium lactate (CL) content (0.22–2.18 g/L) and curing duration (7–28 days) using the response surface methodology (RSM). Scanning electronic microscopy (SEM) was conducted to evaluate the microstructure of calcium precipitated inside the bioconcrete. The results indicated that the optimal conditions for the engineering properties of concrete and durability were determined at 2.18 g/L of CL content after 23.4 days. The actual and predicted values of the compressive strength, splitting tensile strength, flexural strength, and water absorption were 43.51 vs. 43.43, 3.19 vs. 3.19, 6.93 vs. 5.50, and 7.55 vs. 7.55, respectively, with a level of confidence exceeding 95%. The scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX) proved that the amount of calcium increased with the increase in CL content up to 2.81 g/L at 23.4 days, reducing the pores inside the concrete and making it a great potential option for healing of concrete structures