The Design Of A Quick Release Attachment Mechanism For A Hydrofoil Board

<div>The primary objective of this project was to design a quick attach and detach system for use with a surfing foilboard. Foilboards are comprised of a board, mast, and fuselage, onto which wings are attached. These components are generally held together by long bolts, which makes the overall board tedious to assemble and disassemble. Research was conducted on the general concept of attaching components rigidly as well as on the market of current foilboard quick attach mechanisms, and a series of conceptual designs were created from it. All design concepts were rated using metrics generated from both the project objectives and market research, and the top-rated concept was then drawn up in Solidworks. Several design iterations were developed in order to meet both the minimum 300g weight, tensile and compressive strength, and attachment/detachment speed requirements. The design iterations were first validated using a series of Solidworks simulation analyses. Subsequently the final design candidate was analysed using a series of ANSYS Static Structural simulations. The final design can withstand the loads and torques during regular usage as well as cases of the rider standing on the side of the mast while the board is at rest. The design can be attached or detached within one second. It can survive up to 8.769x105 cycles of maximum cyclical loading and is easy to clean.</div>

The Design Of A Quick Release Attachment Mechanism For A Hydrofoil Board

<div>The primary objective of this project was to design a quick attach and detach system for use with a surfing foilboard. Foilboards are comprised of a board, mast, and fuselage, onto which wings are attached. These components are generally held together by long bolts, which makes the overall board tedious to assemble and disassemble. Research was conducted on the general concept of attaching components rigidly as well as on the market of current foilboard quick attach mechanisms, and a series of conceptual designs were created from it. All design concepts were rated using metrics generated from both the project objectives and market research, and the top-rated concept was then drawn up in Solidworks. Several design iterations were developed in order to meet both the minimum 300g weight, tensile and compressive strength, and attachment/detachment speed requirements. The design iterations were first validated using a series of Solidworks simulation analyses. Subsequently the final design candidate was analysed using a series of ANSYS Static Structural simulations. The final design can withstand the loads and torques during regular usage as well as cases of the rider standing on the side of the mast while the board is at rest. The design can be attached or detached within one second. It can survive up to 8.769x105 cycles of maximum cyclical loading and is easy to clean.</div>

What does ‘toughness’ look like? An examination of the breakdown of young and mature leaves under cyclical loading

The material property of leaf toughness is considered the crucial mechanical challenge facing folivorous primates. Mature leaves have higher recorded toughness values than young leaves on average, leading to many assumptions about the patterning of food breakdown that follow a tough/not-tough dichotomy. We tested three hypotheses about how leaves break down under repetitive loading cycles, predicting that mature leaves (i) experience more force during simulated occlusal loads, (ii) more effectively resist fragmentation into small pieces, and (iii) show a more gradual decline in resistance over consecutive cycles than young leaves. Under displacement control using a mechanical testing system, we subjected young and mature leaves to 20 cycles of axial loading using interlocking steel wedges, then collected and quantified the size of the leaf fragments. While we found that mature leaves experienced more overall force than young leaves ( p < 0.001), they also shattered into smaller pieces ( p = 0.004) and showed a steeper decline in their resistance to the cycles over the course of a test ( p < 0.01). These results suggest that putatively ‘tougher’ foods (i.e. mature versus young leaves) do not necessarily resist fragmentation as commonly assumed. The current tough/not-tough paradigm of primate foods may not accurately reflect how leaves break down during masticatory behaviour.

The Effect of the Addition of Graphene Nanoplatelets on the Selected Properties of Cementitious Composites

The aim of the current study is to investigate the properties of graphene nanoplatelets-cementitious composites in a consistent sense. The influence of the addition of 2D graphene nanoplatelets (GNPs) on the workability, setting time, flowability, strengths and piezoresistive properties were studied. The dosage of the GNPs is 0 0.05, 0.1, 0.3, 0.5, 0.7, and 1.0 wt% of the binder material. PVP type surfactant was used to disperse GNPs. The experimental results showed that the addition of GNPs increases the water requirement for normal consistency and decreases the flowability. A small amount of GNPs (0.05 wt%) can facilitate the setting. When the dosage of GNPs is above 0.1 wt%, it leads to the delay of the setting time. In terms of the strengths, the addition of GNPs can considerably promote the flexural strength, while the compressive strength is slightly decreased until 28 days. A pre-treatment procedure consisting of drying specimens at 105°C for 1 day can be regarded as a proper way to enhance the piezoresistive properties of the GNPs-mortar. Piezoresistive properties under two different cyclical loading schemes were measured using the GNPs-mortar with 1 wt% GNPs. It has been shown that the average resistance change rate increases with the amplitude increasing and a reduction is observed for the sustained cyclical loading condition. In the end, the influence of the microcracks on the piezoresistive properties was investigated. This study will contribute to future developments of cementitious composites incorporating GNPs for a variety of applications.

A comparison of shear- and compression-induced mechanotransduction in SW1353 chondrocytes

Mechanotransduction is a biological phenomenon where mechanical stimuli are converted to biochemical responses. A model system for studying mechanotransduction are the chondrocytes of articular cartilage. Breakdown of this tissue results in decreased mobility, increased pain, and reduced quality of life. Either disuse or overloading can disrupt cartilage homeostasis, but physiological cyclical loading promotes cartilage homeostasis. To model this, we exposed SW1353 cells to cyclical mechanical stimuli, shear and compression, for different durations of time (15 and 30 min). By utilizing liquid chromatography-mass spectroscopy (LC-MS), metabolomic profiles were generated detailing metabolite features and biological pathways that are altered in response to mechanical stimulation. In total, 1,457 metabolite features were detected. Statistical analyses identified several pathways of interest. Taken together, differences between experimental groups were associated with inflammatory pathways, lipid metabolism, beta-oxidation, central energy metabolism, and amino acid production. These findings expand our understanding of chondrocyte mechanotransduction under varying loading conditions and time periods.

Investigation of ventriculoperitoneal shunt disconnection for hydrocephalus treatment

OBJECTIVEThis investigation is aimed at gaining a better understanding of the factors that lead to mechanical failure of shunts used for the treatment of hydrocephalus, including shunt catheter-valve disconnection and shunt catheter fracture.METHODSTo determine the root cause of mechanical failure, the authors created a benchtop mechanical model to mimic mechanical stressors on a shunt system. To test shunt fracture, cyclical loading on the catheter-valve connection site was tested with the shunt catheter held perpendicular to the valve. Standard methods were used to secure the catheter and valves with Nurolon. These commercial systems were compared to integrated catheters and valves (manufactured as one unit). To test complete separation/disconnection of the shunt catheter and valve, a parallel displacement test was conducted using both Nurolon and silk sutures. Finally, the stiffness of the catheters was assessed. All mechanical investigations were conducted on shunts from two major shunt companies, assigned as either company A or company B.RESULTSCyclical loading experiments found that shunts from company B fractured after a mean of 4936 ± 1725 cycles (95% CI 2990–6890 cycles), while those of company A had not failed after 8000 cycles. The study of parallel displacement indicated complete disconnection of company B’s shunt catheter-valve combination using Nurolon sutures after being stretched an average 32 ± 5.68 mm (95% CI 25.6–38.4 mm), whereas company A’s did not separate using either silk or Nurolon sutures. During the stiffness experiments, the catheters of company B had statistically significantly higher stiffness of 13.23 ± 0.15 N compared to those of company A, with 6.16 ± 0.29 N (p < 0.001).CONCLUSIONSMechanical shunt failure from shunt catheter-valve disconnection or fracture is a significant cause of shunt failure. This study demonstrates, for the first time, a correlation between shunt catheters that are less mechanically stiff and those that are less likely to disconnect from the valve when outstretched and are also less likely to tear when held at an angle from the valve outlet. The authors propose an intervention to the standard of care wherein less stiff catheters are trialed to reduce disconnection.

Biomechanical Evaluation Comparing Pulvertaft Weave and Side-to-Side Tenorrhaphy Using Porcine Tendons

Background: Pulvertaft Weave (PTW) is an established method of tenorrhapy in tendon transfers. Previous studies have suggested that a Side-to-Side (STS) tenorrhapy is easier to perform has the same advantages and has greater load to failure, ultimate load and stiffness compared to PTW. However, there is insufficient data comparing behaviour of STS and PTW during cyclical loading. The aim of this study is to compare these two methods in terms of creep after cyclic landing. Methods: Fresh porcine flexor digitorum tendons were used. Ten tendon PTW and ten STS repairs were performed. Cross sectional diameter was measured. The tendon repairs were tested by applying tension up to 25N for 100 cycles, followed by tension up to 75N for 100 cycles, followed by loading to failure. Force-displacement data was used to determine the creep of the repaired tendon. Results: All tendons survived 100 cycles of loading at 25N. After 1 cycle of loading, the mean cyclic creep in the PTW group was almost 3 mm larger than in the STS group (p = 0.046). After 100 cycles, the mean cyclic creep in the PTW group was 4.4 mm larger (p = 0.008). The cyclic creep rate was significantly larger in the PTW group (p < 0.001). All STS but only four PTW repairs survived after cyclic loading at 75N (p = 0.01). After 1 cycle and 100 cycles, mean creep of the surviving PTW samples was almost 7 mm (p = 0.006) and almost 9 mm (p = 0.004) larger than the STS group. The mean load to failure was four times larger in the STS group than the PTW group (p = 0.004). Conclusions: STS repairs have a significantly smaller permanent elongation after cyclic loading at 25N and 75N, a significantly smaller cyclic creep rate, require a significantly larger load to fail. This implies that STS repairs are less likely to elongate after cyclic loading and can withstand greater loads. These properties can be valuable in allowing patients to commence mobilisation immediately after surgery.