Key Engineering Materials Vol. 843

Abstract: The Innovate-UK-funded Composite Lightweight Automotive Suspension System (CLASS) project, led by Ford Motor Company and partnered by Gestamp UK, GRM Consulting and WMG, investigated the use of carbon fibre reinforced composite materials to decrease the weight of a complex automotive rear suspension component in support of reduction in vehicle emissions. A multi-material design comprising discontinuous fibre composite (C-SMC), aligned fibre composite laminate (prepreg) and steel was developed. A high volume hybrid compression moulding manufacturing process was developed at WMG, achieving total press cycle times of around 5 minutes. Prototype parts were manufactured and evaluated using materials characterisation techniques to validate the manufacturing methods. The optimum C-SMC charge pattern was investigated to achieve complete fill with minimal pre-processing. Destructive and nondestructive analysis of the hybrid parts was performed to understand resultant hybrid material macrostructure. This innovative design and manufacturing process resulted in a component 35% lighter than the original multi-piece steel design.

Abstract: This research project aims to analyze the economic feasibility of Additive Manufacturing (AM) as supportive technology in Injection Molding (IM) tool manufacturing by estimating the potential cost-savings and lead-time reduction. Cost and lead-time considerations during small part quantity production are analyzed by developing an extended estimation model for the integration of AM in tool production. Based on six different real reference parts, the developed model shows the projected savings and the current limitations of AM applications in tool production due to material constraints. Furthermore, this extended model offers a holistic view on part cost and lead-time information, by considering tooling as well as production phases in IM and integrating tool life as a key variable. Hence, this research project closes a literature gap and facilitates the integration of AM into the IM process chain.

Abstract: Over last decades composite materials gained even more interests in many industries due to theirs effective properties which may be apparently different (better) then constituents itself. By specific layout and distribution of composite components we can achieve desired properties in macro scale, e.g. high elasticity and low conductivity at the same time. On all interfaces, by perfect contact between phases, there will appear jump of gradient field (displacement or temperature) of unknown magnitude. This magnitude depends in fact, for the heat transfer problem, inter alia on the ratio of conductivities of composite constituents lying next to interface. Values of these oscillation magnitudes are case of our study here. The conductor under considerations is a two-phase, periodic laminate subjected to initial-boundary conditions assuring unidirectional heat flow, perpendicular to the laminas. Ratios of material properties are assumed as random variables of known probabilistic distribution. We will give an answer to the question: is the jump function of temperature gradient a random variable of Gaussian distribution In order to have a good description to considered problem we have decided on the use of tolerance averaging technique.

Abstract: This research analyzed the printability of compostable films commercialized in the Thai market such as PLA/PBAT and PBAT/starch; and to comply with EN 13432 standard by using flexographic water based ink. A narrow web flexographic printing press was set up and opperated. Print quality parameters such as optical density, tone reproduction, print contrast and print uniformity were investigated. Results showed that these compostable films were hydrophobic in nature, in combination with fracture and voids of substrates’ surface. Even the substrates could be printed relatively well but showed poor ink adhesion. Surface treatment, therefore, was necessary, but having limitation. Anilox line screen 700 lpi and printing speed at 30 m/min were preferable to achieve the optimum tone reproduction and print contrast. This was based on the image resolution of 133 lpi and corona dosage at 500 watt-min/m². Images of printed samples from SEM and SPM indicated that the fracture surface and void of films could lead to decrease their printability. It was found that starch blend gave better results as being a filler of the surface roughness of the substrate..

Abstract: In this study, the closed die forging of aluminium based compoistes reinfoced with CNTs (1vol% and 3vol%) were investigated. Initially, the composites were fabricated using high energy ball milling followed by compaction and sintering. The microstructural results showed that finer grain size and homogeneous dispersion of CNTs were obtained. Composites with up to 97% densification were produced when fine open porosities were removed by closed die forging. The results imply that the hardness and compressive strength of composites with 3vol.% of CNTs has improved without any deterioration. In addition, workability behaviors of composites were investigated by cold upsetting test. For that pore reopening test was performed to confirm the closure of micro-pores after the closed die forged, and to further analyze the densification of the composites. Typical cases, as the pores were not re-opened even after increasing the strain, additional forming is possible up to large deformations.

Abstract: In-situ monitoring method of FRP (Fiber Reinforced Plastics) by built-in sensors is a key technology for developing future and high-reliable composite structures. The Rayleigh scattering-based distributed optical fiber sensor has high spatial resolution of 1mm and good embeddability into FRP and then it can be considered that the sensor is very suitable to in-situ monitoring of FRP. In the present paper, process monitoring and damage identification of FRP were conducted. In the process monitoring, flow-front of silicon oil impregnating into glass textile during VaRTM (Vacuum-assisted Resin Transfer Molding) process was measured. Comparing to visual observation results, it appeared that the maximum slope position of strain distribution showed flow-front position. In the health monitoring, damage identification of cross-ply GFRP laminates with delamination by the attached distribution optical fiber sensors was carried on. From the results, it was found that the strain varied largely on the delaminated section and then the delamination was detectable from the surface strain distribution measured by the optical fiber sensor.

Abstract: Using the electrical-field (E-field) stress at the positive and negative directions to generate the degradation and form the recovery effect is a useful metrology to evaluate the integrity of gate dielectric. This consequence deeply influences the drive current of 2D MOSFET or 3D FinFET species. According to the experimental results with the short and long-term stresses, we found the electrical performance of Hf-based tested devices represented the better recovery than that of SiON-based ones. And the recovery effect is more regular, not only in V_T shift, but in gate leakage due to the high-k dielectric probably providing the polar effect and more trap assistants.

Abstract: The MRI (Magnetic Resonance Imaging) has been used as one of the powerful tools for medical diagnoses. Its usefulness is, however, still restricted because of the low spatial resolution and long measuring time mainly due to the low NMR (Nuclear Magnetic Resonance) signals relative to the noise levels. To overcome these restrictions, we started developing a method to remarkably enlarge the NMR signals about 10 years ago. We employ a method to hyperpolarize the nuclei, where the “hyperpolarize” means to artificially generate the nuclear polarization by many orders (10²~10⁶) of magnitude higher than the ordinary NMR signals currently in use. The hyperpolarized MRI would enable us to provide images with much higher spatial resolution and shorter measuring time than ever. Several techniques for hyperpolarization have been put into practical use; the BF (Brute Force) method, PHIP (Parahydrogen Induced Polarization) method, Laser optical pumping, DNP (Dynamic Nuclear Polarization), and so on. The experimental study on the hyperpolarization of ³He by the BF method, and that of ¹⁹F in PFC (Perfluorocarbon, known as an artificial blood) by the PHIP method has gotten started. In the former method, we use an extremely low temperature realized by the Pomeranchuk cooling in combination with ³He/⁴He dilution refrigerator and high magnetic field. In the latter method, we use the hydrogenation of the parahydrogen in the unsaturated hydrocarbon substrate at room temperature. Very recently, we started developing a novel type of the hyperpolarized MRI named HMM (Hyperpolarized Metabolic MRI) hoping for the cancer diagnosis.

Abstract: In cases where we can achieve integrated sensors using only layers already in the standard IC layers, the only compatibility issues may be the requirement for additional etch steps. In cases where additional layers are required, either for sensing or protection, we have to consider the compatibility of the materials. These issues can be thermal budget during processing, mechanical stress or chemical contamination. In some cases, this led to the option of hybrid, where the sensor and electronics are on separate chips, but combined in a single package. This paper will examine the development of integrated sensors, and the issues combining additional layers with a standard IC process.