Material Design & Processing Communications最新文献

In this paper, deterministic and probabilistic approaches of failure modeling of high-density polyethylene (HDPE) pipes have been introduced. They are based on determining the experimental parameters of HDPE through burst and tensile tests. In fact, reliability criteria have been determined through 11 damages models, and the critical life fraction have been reached for both of the approaches. Besides, the mean time between failures (MTBF), the probability density, and the failure rate have been defined for each loading level by using the Weibull parameters. The comparison of the failure rate bathtub curves to those obtained through the damage-reliability curves present a fast tool to choose accurately the maintenance decision to undertake the sudden failures' occurrence and oblige the preventive measures instead of the corrective ones. The reliability prediction through a simplified equation of MTBF have been developed. The introduced approaches can be applied to all the thermoplastic pipes.

Nature-inspired materials based on triply periodic minimal surfaces (TPMS) are very attractive in many engineering disciplines because of their topology-driven properties. However, their adoption across different research and engineering fields is limited by the complexity of their design process. In this work, we present MSLattice, a software that allows users to design uniform, and functionally grade lattices and surfaces based on TPMS using two approaches, namely, the sheet networks and solid networks. The software allows users to control the type of TPMS topology, relative density, cell size, relative density grading, cell size grading, and hybridization between lattices. These features make MSLattice a complete design platform for users in different engineering disciplines, especially in applications that employ additive manufacturing (3D printing) and computational modeling. We demonstrate the capability of the software using several examples.

Despite all other technologies reported in literature, electrospinning has gained significant importance because of its ability to fabricate nanostructures with distinctive properties, including high surface area and porosity. Electrospinning has been evolved as the most widely used technique in the recent century. It has been employed in various biomedical applications such as tissue-engineered vascular grafts. This can develop fibrous scaffolds that mimic the structure of extracellular matrix of native blood vessels, suitable for the promotion of cell adhesion, proliferation, and cell growth. There is a growing demand for tissue-engineered vascular grafts for the replacement of damaged or defected blood vessels in cardiovascular diseases. The purpose of this review is to summarize recent developments related to electrospun vascular grafts with different synthetic and natural polymers and electrospinning parameters that affect the final properties of vascular grafts. The main focus of this review is also to describe the previously used materials for electrospun vascular grafts and their applications with respect to small and large diameter vascular grafts.

The novel manufacturing concept for embedding fiber optic Bragg grating (FOBG) sensors allowed for the damage-free embedding of the FOBG fiber to the laminate structure. In this article, coupons with embedded FOBG fiber were tested under alternating bending spectrum and for different peak loads ranging from 30% and up to 60% of ultimate tensile strength at their bottom surface. The differences between the strain measurements of the surface-attached strain gauge and the embedded sensor were almost 2.4% and approximately the same for all the applied peak loads. Application of 65,000 fatigue cycles on several coupons was assessed to simulate the fatigue-loading of the aircraft structures over their life span. The fatigued-coupons were tested afterwards at the same alternate bending-loading spectrum, and their strain measurements were compared against the respective loading spectrum without prior fatigue. The strain measurement differences at peak loads was of the order of 3.0% for the small-applied loads and exceeded 7.0% for the high-applied loads. Fatigue damage after 65,000 cycles was not essentially accumulated in the sensing area of the FOBG sensor, and therefore, its current exploitation in real aircraft structures, for example, a 2-m-long Ω-stringer from carbon preimpregnated fibers from an Aerospace Industry with monitoring capabilities, is proved.

The practice of using a massive amount of environmental unfriendly and toxic petroleum-based materials in tissue engineering and biomedical fields demands the materials, which are biodegradable, renewable, environmentally friendly, biocompatible, and bioactive. So, renewable polymers have got considerable attention due to their numerous desirable properties. The nanofibers that are prepared from renewable materials and their blends can integrate the properties of both nanofibers and renewable polymers. Development of scaffolds that mimic the construction of tissues at nanoscale is a great challenge for tissue engineering. Electrospinning is the most promising technique for nanofibers formation. Nanofibers provide a platform for cell adhesion, proliferation, and differentiation. Therefore, nanofibers from sustainable materials have been used in tissue engineering and biomedical fields. In this review, methods for nanofibers fabrication, sustainable nanofibers made from natural and synthetic polymers and their applications in tissue engineering and biomedical field, have been emphasized.

In recent years, strain energy-based criteria used to predict the static and fatigue strength of notched components have attracted the attention of many researchers. The reasons are a lot. The energy density is first of all a scalar quantity, and when calculated by finite element methods, it does not need a fine mesh, which speeds up significantly the design of complex as well as large structures. Among these approaches, the average strain energy density (ASED) states that failure will occur when the strain energy averaged over a control volume of radius R_c will reach a critical value. R_c is a material property to be determined by experiments. In the present work, the ASED criterion is applied to heavy section ductile irons containing defects. It is found that a narrow ASED-based scatter band is able to summarize the fatigue behaviors of different ductile irons families.

First published: 08 August 2019 https://doi.org/10.1002/mdp2.101

The authors would like to draw attention to the following error:

In Section 2.1: Prototypes configuration and materials, the thickness of the foils was incorrectly stated as 50 mm. The correct value is 50 μm.

The paragraph should appear as follows:

‘Two types of prototypes were built, either with a single or double target material cylinders. The single-cylinder prototypes were produced to study the target to cladding materials bonding whilst the double-cylinder prototypes were produced to study the target to target materials bonding. Ta foils were eventually introduced between the materials as diffusion interfacial aids. The foils’ thickness was fixed in 50 μm, following literature recommendations, to maximize the bonding strength.14, 18 The two types of prototypes are represented in Figure 2 with their respective components'.

The authors apologise for any misunderstanding arising from this error.

Fretting and fretting fatigue are important considerations to be made in the design and development of medium-speed reciprocating engines. Predictive capabilities for safe-life design often rely on very simple empirical parameters and experience. Practices are briefly reviewed, and opportunities for more sophisticated methodologies are highlighted. It is concluded that more research into fretting fatigue with complex load sequences are needed.

Early observations of cracks protect the teeth. The crack in teeth initiates due to the flaws, defect, or inappropriate fillings design. The brittleness allows the crack to extend from any notches over the enamel due to the lower plasticity. Therefore, in this issue, linear elastic fracture mechanics (LEFM) assumptions will be used instead of the elastic–plastic fracture mechanics (EPFM). Traditionally, the vertical crack in the teeth is predominated. The load distributions over the crown and the cyclic loading will propagate the crack. There are limited works trying to simulate the crack in the teeth. In this work, the crack path (CP) and the fracture behavior of the tooth have been simulated. It was shown that LEFM is sufficient for such simulation.

In this research, numerical simulations have been performed for carbon/epoxy laminated composites. Two methods were utilized: the extended finite element method and the cohesive zone modeling approach. In addition, experimental works were done according to the ASTM-D5528 standard for double cantilever beam specimens under Mode I displacement-controlled tensile loading. Besides, the loading rate was considered as 0.05, 0.5, 5, and 50 mm/min. During testing, a charge-coupled device (CCD) camera was used to detect the crack length and the initial crack tip opening displacement by the digital image correlation technique. Experimental data were analyzed to find fracture properties by the compliance calibration method, the modified compliance calibration approach, and the modified beam theory. Consequently, there was a good adaptation between numerical and experimental results, obtained by the cohesive zone modeling approach and the extended finite element method, for predicting the maximum force, the energy release rate, and also the initial crack tip opening displacement, under different loading rates. Moreover, the results of the extended finite element method had higher errors than those of the cohesive zone modeling approach.