scholarly journals INVESTIGATIONS IN THE STRENGTH OF GLULAM MULTILAYERED BEAMS UNDER A SHORT-TIME SHEAR/MEDINIŲ KLIJUOTŲ DAUGIASLUOKSNIŲ SIJŲ STIPRUMO TYRIMAI VEIKIANT TRUMPALAIKĖMS SKERSINĖMS SKERSINĖMS JĖGOMS

1998 ◽  
Vol 4 (1) ◽  
pp. 5-11
Author(s):  
Rimantas Čechavičius
Keyword(s):  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Lateral Direction ◽  
Load Bearing ◽  
Prestressing Force ◽  
Lateral Tension ◽  
Wide Range ◽  
Wood Fibres ◽  
Comparison Of The Results ◽  
Short Time

The author of the article has performed wide-range tests of glulam beams. The objective of the tests is increasing of load bearing capacity of such beams under shear. As a result 5 inventions have been suggested and confirmed. In total 44 beams of various types were tested under the action of short and long-time loadings. These investigations have verified a new method for increasing load bearing capacity of glulam beams. The essence of the method was the utilisation of prestressed elements in multilayered beams. It allows to increase load bearing capacity of such elements under shear and decrease or eliminate the influence of lateral tension stresses on their resistance. Totally, 30 beams have been tested for the influence of short-time forces: 6 of them are multilayered with pre-stressed elements, made by the offer of invention No 954237; 8 analogous beams for comparison of the results are made of squared timber, board package, multilayered without prestressed elements; 16 different beams for additional investigations of methods of experiments and closer definition of separate technological factors. All beams failed because of shear. It has been proved by experiments that plywood brass in multilayered beams not only increases the strength of the beam, but also prevents the element from a sudden failure, increases its reliability. Longitudinal cracks have appeared in the zones of neutral axes of prestressed multilayered beams before the failure of them, while the load was 0,93–0,98 of ultimate the width of the crack was 0,7–0,8 mm, and the shear deformation was 2–6 mm at the moment of failure. The strength of the beams under short-time shear depending on the level of prestressing force (σy = = 1,5…2,25 MPa) increased 9–10% and crack resistance increased 9–22% in comparison with unpresstressed beams. A short description of invention No 954237 has also been given (see Fig 6). Layers of a load bearing multilayered element with wood fibres oriented along the axis of the member (1) are precompressed laterally to the wood fibres (5). Compression force should not cause stresses (σy) higher than the point of wood proportionality in lateral direction. These layers (1) are glued with the layers where wood fibres are directed laterally to the axis of the element (2) and they are shorter in value Δ ≥ σy · h/E90 than layers (1). Horizontal prestressing of multilayered element (4) has to ensure a qualitative cohesion. It is possible to use structural plywood instead of wood layers with fibres lateral to the axis of the element. The use of this method does not only increase the resistance of glulam elements to short-time shear, but also ensures a better reliability of such structures.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

scholarly journals Modulation of kinesin’s load-bearing capacity by force geometry and the microtubule track

2019 ◽  
Author(s):  
Serapion Pyrpassopoulos ◽  
Henry Shuman ◽  
E. Michael Ostap
Keyword(s):  
Cell Division ◽  
Bearing Capacity ◽  
Organelle Transport ◽  
Vertical Force ◽  
Long Distance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Wide Range ◽  
Single Bead ◽  
Attachment Duration

AbstractKinesin motors and their associated microtubule tracks are essential for long-distance transport of cellular cargos. Intracellular activity and proper recruitment of kinesins is regulated by biochemical signaling, cargo adaptors, microtubule associated proteins and mechanical forces. In this study, we found that the effect of opposing forces on the kinesin-microtubule attachment duration depends strongly on experimental assay geometry. Using optical tweezers and the conventional single-bead assay we show that detachment of kinesin from the microtubule is likely accelerated by forces vertical to the long-axis of the microtubule due to contact of the single bead with the underlying surface. We used the three-bead assay to minimize the vertical force component and found that when the opposing forces are mainly parallel to the microtubule the median attachment duration between kinesin and microtubules can be up to 10-fold longer than observed using the single-bead assay. Using the three-bead assay, we also found that not all microtubule protofilaments are equivalent interacting substrates for kinesin and that the median attachment duration (median-Δt) of kinesin varies by more than 10-fold, depending on the relative angular position of the forces along the circumference of the microtubule. Thus, depending on the geometry of forces across the microtubule, kinesin can switch from a fast detaching motor (median-Δt < 0.2 s) to a persistent motor that sustains attachment (median-Δt > 3 s) at high forces (5 pN). Our data show that the load-bearing capacity of the kinesin motor is highly variable and can be dramatically affected by off-axis forces and forces across the microtubule lattice which has implications for a range of cellular activities including cell division and organelle transport.Significance StatementKinesins are cytoskeletal motors responsible for the transport of cargoes along microtubules. It is well known that opposing forces decrease kinesin’s speed and run length. In this study, we found that when the pair of opposing forces applied on the kinesin-microtubule complex are parallel to the microtubule, the ability of kinesin to remain attached to the microtubule can vary by more than an order of magnitude depending on the relative azimuthal position of the pair of forces along the periphery of the microtubule. These results reveal a previously unknown versatility of kinesin’s load bearing capacity and as such have implications for the potential physiological roles of kinesin in a wide range of cell activities, including organelle transport and cell division.

Increased load bearing capacity of mechanically joined FRP/metal joints using a pin structured auxiliary joining element

2020 ◽  
Vol 62 (1) ◽  
pp. 55-60
Author(s):  
Per Heyser ◽  
Vadim Sartisson ◽  
Gerson Meschut ◽  
Marcel Droß ◽  
Klaus Dröder
Keyword(s):  
Bearing Capacity ◽  
Load Bearing Capacity ◽  
Load Bearing

Load-Bearing Capacity of Direct Inlay-Retained Fibre-reinforced Composite Fixed Partial Dentures with Different Cross-Sectional Pontic Design

2017 ◽  
Vol 68 (1) ◽  
pp. 94-100
Author(s):  
Oana Tanculescu ◽  
Adrian Doloca ◽  
Raluca Maria Vieriu ◽  
Florentina Mocanu ◽  
Gabriela Ifteni ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Fracture Pattern ◽  
Load Bearing Capacity ◽  
Cross Sectional ◽  
Load Bearing ◽  
Reinforced Composite ◽  
Polyethylene Fibre

The load-bearing capacity and fracture pattern of direct inlay-retained FRC FDPs with two different cross-sectional designs of the ponticwere tested. The aim of the study was to evaluate a new fibre disposition. Two types of composites, Filtek Bulk Fill Posterior Restorative and Filtek Z250 (3M/ESPE, St. Paul, MN, USA), and one braided polyethylene fibre, Construct (Kerr, USA) were used. The results of the study suggested that the new tested disposition of the fibres prevented in some extend the delamination of the composite on buccal and facial sides of the pontic and increased the load-bearing capacity of the bridges.

scholarly journals The energy absorption behavior of novel composite sandwich structures reinforced with trapezoidal latticed webs

2021 ◽  
Vol 60 (1) ◽  
pp. 503-518
Author(s):  
Juan Han ◽  
Lu Zhu ◽  
Hai Fang ◽  
Jian Wang ◽  
Peng Wu
Keyword(s):  
Bearing Capacity ◽  
Energy Absorption ◽  
Sandwich Structure ◽  
Ultimate Load ◽  
Sandwich Structures ◽  
Elastic Displacement ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Sandwich ◽  
Composite Sandwich Structures

Abstract This article proposed an innovative composite sandwich structure reinforced with trapezoidal latticed webs with angles of 45°, 60° and 75°. Four specimens were conducted according to quasi-static compression methods to investigate the compressive behavior of the novel composite structures. The experimental results indicated that the specimen with 45° trapezoidal latticed webs showed the most excellent energy absorption ability, which was about 2.5 times of the structures with vertical latticed webs. Compared to the traditional composite sandwich structure, the elastic displacement and ultimate load-bearing capacity of the specimen with 45° trapezoidal latticed webs were increased by 624.1 and 439.8%, respectively. Numerical analysis of the composite sandwich structures was carried out by using a nonlinear explicit finite element (FE) software ANSYS/LS-DYNA. The influence of the thickness of face sheets, lattice webs and foam density on the elastic ultimate load-bearing capacity, the elastic displacement and initial stiffness was analyzed. This innovative composite bumper device for bridge pier protection against ship collision was simulated to verify its performance. The results showed that the peak impact force of the composite anti-collision device with 45° trapezoidal latticed webs would be reduced by 17.3%, and the time duration will be prolonged by about 31.1%.

scholarly journals A Modified Pressure–Sinkage Model for Studying the Effect of a Hard Layer in Sandy Loam Soil

2021 ◽  
Vol 11 (12) ◽  
pp. 5499
Author(s):  
Nihal D. Salman ◽  
György Pillinger ◽  
Muammel M. Hanon ◽  
Péter Kiss
Keyword(s):  
Bearing Capacity ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
High Fidelity ◽  
Load Bearing Capacity ◽  
Soil Thickness ◽  
Load Bearing ◽  
Hard Layer ◽  
Loam Soil ◽  
New Perspective

The applicability of the typical pressure–sinkage models used to characterize the soil’s bearing properties is limited to homogeneous soils (infinite thickness) that have no hard layer. At a given depth, a hard layer can have a considerable impact on the soil’s load-bearing capacity. It is thus necessary to alter the pressure–sinkage equation by taking this condition into account when assessing the load-bearing capacity. The present paper aims to determine a simple, high-fidelity model, in terms of soil characterization, that can account for the hard layer affection. To assess hard layer affection in this paper, a plate sinkage test (bevameter) was conducted on sandy loam soil. To this end, the soil was prepared by considering three bulk densities and two soil thickness levels at 7–9% moisture content levels. According to the results, this paper put forth a new perspective and related equations for characterizing bearing performance. The sinkage modulus (k) is an intrinsic soil parameter that has a determined unit of N/cm2 and is significant for managing the bearing performance. The results showed that the new modulus sinkage model incorporates the main factor of the rigid layer effect involving high fidelity that the conventional models have failed to account for.

Sign in / Sign up

Export Citation Format

Share Document