8 research outputs found
Localised low velocity impact performance of FLAX/PLA biocomposites
Natural fibre composites are fast emerging as a viable alternative to traditional
materials and synthetic composites. Their low cost, lightweight, good mechanical
performance and their environmentally friendly nature makes them an ideal choice for
the automotive sector. The automotive industry has already embraced these composites
in production of non-structural components. At present, however, research studies into
composites made of natural fibres/bio-sourced thermoplastic resins are at infancy stage
and such works are rare in the literature.
This study therefore focuses on the mechanical properties of poly(lactic) acid (PLA) flax
reinforced composites for structural loaded components. The aim was to investigate the
performance of flax/PLA biocomposites subjected to localized low velocity impacts. To
start with, a detailed literature study was conducted covering biocomposites and PLA in
particular. Next, a series of composite samples were manufactured. Morphological and
thermal studies were also conducted in order to develop an in-depth understanding of
their thermo-mechanical properties, including crystallinity, thermal response and their
related transition temperatures. This was followed by localized impact studies. The
influence of temperature, water uptake and strain rates to the material tensile strength
and modulus, as well as the damage characteristics and limits that lead to failure were
studied. Furthermore, in the present work different methods and existing material
models to predict the response of biocomposites were assessed. A case study was then
performed using these models to understand, develop and improve the side crash
performance of a superlight city car prototype. ...[cont.
Thermo-mechanical performance of poly(lactic acid)/flax fibre-reinforced biocomposites.
In this study, the thermo-mechanical performance of flax fibre reinforced poly lactic acid (PLA) biocomposites was investigated for the potential use in load bearing application such as body-in-white and body structures in the automotive sector. Focus was given into the relationships between the thermal and mechanical properties, and the material response under different loading and environmental conditions. The strength (72. MPa) and stiffness (13. GPa) of flax/PLA composites investigated indicate a very promising material to replace traditional choices in load bearing application. The PLA's crystallinity was measured to approximately 27%. Annealing above 100. °C for an hour decreased that value to 30%, but analysis of tensile results of annealed specimens reveals a significant reduction of both the tensile strength and modulus. This reduction is associated with micro-cracking that occurred on the surface of PLA during the heating as well as deterioration of the flax properties due to drying. The study results show that strength and modulus increased with increasing strain rates, while elongation at break reduces respectively. A modulus of 22. GPa was recorded in 4.2. m/s crosshead velocity. Further, flax/PLA showed significantly higher modulus than flax/epoxy for the composites studied. Improvement of the interfacial bonding and the temperature characteristics, combined the thermoplastic nature of PLA, demonstrates that flax/PLA composites is ideal for use in structural automotive applications
Nested Topology Optimization Methodology for Designing Two-Wheel Chassis
Weight reduction has always been a challenge for the automotive industry, mainly to reduce consumption but also improve handling. In electric vehicle design, the battery packs, their shape and positioning are critical aspects that determine the overall weight, weight distribution and, as a consequence, the efficiency, dynamics and stability of the vehicle. This presented a new challenge, to manage this necessary and inflexible weight and volume, developing the vehicle chassis around it and in the best possible way, without compromising the overall efficiency and behaviour. In this work, a methodology for nested topology optimization has been developed which combines structural topology optimization and battery pack shaping and positioning. The new methodology is implemented, without limiting its applicability, into the framework of the commercial software Hyperstudy by Altair.
Document type: Articl
Nested Topology Optimization Methodology for Designing Two-Wheel Chassis
Weight reduction has always been a challenge for the automotive industry, mainly to reduce consumption but also improve handling. In electric vehicle design, the battery packs, their shape and positioning are critical aspects that determine the overall weight, weight distribution and, as a consequence, the efficiency, dynamics and stability of the vehicle. This presented a new challenge, to manage this necessary and inflexible weight and volume, developing the vehicle chassis around it and in the best possible way, without compromising the overall efficiency and behavior. In this work, a methodology for nested topology optimization has been developed which combines structural topology optimization and battery pack shaping and positioning. The new methodology is implemented without limiting its applicability, into the framework of the commercial software Hyperstudy by Altair
Finite element dynamic simulation of whole rallying car structure: Towards better understanding of structural dynamics during side impact
Side impact accidents against a tree or pole remain the most dangerous accident
scenarios in rally cars. Statistical data shows that 52% of the fatalities
between 2004 and 2009 concern crashes against a rigid pole by the track sides,
whilst among those more than 60% were side impacts. Despite the present
scientific efforts, rallying cars side impacts are still among the least
understood primarily due to limited space between the occupant and door sill,
evolving safety regulations and vehicle dynamics. In this study, finite element
dynamic characteristics of the whole car were studied. The finite element model
consisted of the whole car structure and 241 parts including the engines, tyres
and the suspension members with 4 different element types and 7 material models.
All structural parts were modelled as low-carbon steel with the piecewise-
linear-plasticity material model (mat 24). The tyres were modelled with the
Blatz-Ko rubber material (mat 07) whilst also rigid and other materials (mat
020, 01, 09, S01 and S02) were used to represent different parts of the model,
as the suspension members, suspension links and the engine. A rollcage and two
racing seats were modelled with four-node shell elements and the use of
piecewise-linear-plasticity and composite-damage materials respectively. A semi-
cylindrical pole of 200mm diameter was also designed and modelled as a rigid
body. The model was used to first investigate the dynamics of the crash, and
later run a wide range of simulations and parametric studies in the cage, the
car's floor and the seats. The important findings from the study are presented,
conclusions drawn and scope for further development outlined
Cellulose-Based Bio- and Nanocomposites: A Review
Cellulose macro- and nanofibers have gained increasing attention due to the high
strength and stiffness, biodegradability and renewability, and their production
and application in development of composites. Application of cellulose
nanofibers for the development of composites is a relatively new research area.
Cellulose macro- and nanofibers can be used as reinforcement in composite
materials because of enhanced mechanical, thermal, and biodegradation properties
of composites. Cellulose fibers are hydrophilic in nature, so it becomes
necessary to increase their surface roughness for the development of composites
with enhanced properties. In the present paper, we have reviewed the surface
modification of cellulose fibers by various methods. Processing methods,
properties, and various applications of nanocellulose and cellulosic composites
are also discussed in this paper