Search

Curved laminates in aero-structures, such as the L-angle sections where webs and flanges meet, are prone to delamination due to high interlaminar stresses in these regions. Some efforts to investigate delamination in these structures can be found in the literature but commonly structures are limited to unidirectional layups or modelling approaches are constrained to the cohesive element based methods. In this work, multi-directional L-angle laminates were manufactured using unidirectional prepregs and tested under four-point bending load conditions to examine the interface damage. Acoustic emission technique was used to assist the capture of damage initiation and propagation. Three interface modelling strategies for predicting delamination, namely cohesive element, cohesive surface and perfectly bonded interface were used in the numerical study. The interface damage behaviour was successfully predicted by the simulation methods and differences among the strategies were compared. [ABSTRACT FROM AUTHOR]

Summary: In this study, we examine the role of founders' need to belong and tertius iungens orientation (i.e., the tendency of bringing people together and coordinating among others) in the context of new ventures. We propose and document evidence that a founder's tendency to engage in tertius iungens oriented networking is positively associated with new venture performance. We also reveal that a founder's need to belong is a significant motivational antecedent of the founder's tertius iungens orientation. Further, the need to belong–networking orientation linkage is stronger for founders in new ventures at the early product development stage than those at the late product development stage. We tested our hypotheses using survey data collected with a two‐wave sample of new ventures in China. We discuss the theoretical significance of studying the need to belong and tertius iungens orientation for social networks and entrepreneurship literatures, as well as the practical implications for managing a successful new venture. [ABSTRACT FROM AUTHOR]

Rapeseed is the major oil crop with the largest planting area in China. However, its productivity and cultivation area are severely affected by low temperature (LT) stress. This review summarized research progresses on evaluation of LT tolerance, molecular mechanisms of LT responses in rapeseed, and breeding of novel rapeseed variety with LT resistance. The application of genome wide association study (GWAS) and multi-omics in ongoing LTrelated research were highlighted, which had theoretical significance in exploring genetic resources for LT resistance, and elucidating regulation mechanism of LT response in rapeseed. [ABSTRACT FROM AUTHOR]

This work presents the first method for generating triangular surface meshes in three dimensions for the NURBS-enhanced finite element method. The generated meshes may contain triangular elements that span across multiple NURBS surfaces, whilst maintaining the exact representation of the CAD geometry. This strategy completely eliminates the need for de-featuring complex watertight CAD models and, at the same time, eliminates any uncertainty associated with the simplification of CAD models. In addition, the ability to create elements that span across multiple surfaces ensures that the generated meshes are highly compliant with the requirements of the user-specified spacing function, even if the CAD model contains very small geometric features. To demonstrate the capability, the proposed strategy is applied to a variety of CAD geometries, taken from areas such as solid/structural mechanics, fluid dynamics and wave propagation. [Display omitted] • The first method to create 3D surface meshes tailored for NEFEM. • Avoided de-featuring before meshing and eliminated geometric discretisation error. • Elements can traverse multiple surfaces to respect user-specified mesh size. • Significantly improved minimum element size to relax explicit time-step requirement. [ABSTRACT FROM AUTHOR]

We examined, in five studies, the relation between nostalgia and financial risk taking. We hypothesized that nostalgia increases risk taking by fostering perceptions of social support. In Study 1, we established the basic effect of nostalgia and increased risk taking. In Study 2, we used a measurement-of-mediation approach to specify the underlying mechanism. Perceived support from family members, rather than from significant others or friends, mediated the relation between nostalgia and risk taking. In Studies 3 to 4, we further specified the mediating mechanism (i.e., family social support) and established direction of causality by using an experimental-causal-chain approach. Finally, in Study 5, we provided direct experimental evidence of the full mediation model. Taken together, nostalgia galvanizes perceived family support, which propels individuals toward financial risk. [ABSTRACT FROM AUTHOR]

With the development of the high power laser facilities, laser resistance of pulse compression grating is getting increased attention. The metal dielectric mixed grating (MDMG) is widely studied, because it has wide diffraction bandwidth, low surface stress and potential high threshold. The effect of nodular defect size on damage of MDMG is studied by experiments and theoretical analysis in two typical cases. The initial damages appear in the district of nodular defect due to local electric field enhancement induced by nodular defect, which is different with the initial damage located in grating pillar of the perfect MDMG. Laser induced ionization theory is introduced to describe the damage process and give a quantitative analysis on the relationship of laser damage and nodular defect size. It is concluded that local electric field enhancement in nodular defect area would cause the electron density to reach the critical value and lead to the damage occurrence, and nodule damage critical diameters are 1400 nm and 1500 nm respectively in case 1 (seed under the grating pillar) and case 2 (seed under the grating groove) which will lead to nodule damage initiation. • The initial damages appear in the district of nodular defect which is different with the initial damage of perfect MDMG. • The nodule damage reason is that electron density reaches to critical value owing to local electric field enhancement. • Nodule damage critical diameter are 1400nm and 1500nm in case 1 and case 2 (seed under grating pillar and grating groove). [ABSTRACT FROM AUTHOR]

An efficient and practical solution to a class of global function optimization is proposed. The new algorithm consists of a stochastic search of initial guesses and a gradient-based solution-finding algorithm. The key idea is to introduce an auxiliary cost function that can indicate whether the gradient-based solution-finding process goes toward a global minimum of the cost function and that helps us to prevent the process from going to local minima. Simulation examples are used to show the mechanism, power, and restrictions of the approach. Index Terms--Auxiliary cost function, global optimization, optimization.

• The temperature gradient and thermal strain show different characteristics in continuous-wave (CW) mode and pulsed-wave (PW) mode during laser additive manufacturing. • In the direct laser deposition process, residual stress was reduced by about 61% using PW laser mode. • The reduction of temperature gradient and stress release contributing to the reduction and homogenization of the residual stress in PW laser mode. Components manufactured by direct laser deposition (DED) are prone to produce excessive residual stress due to its rapid heating by laser and cooling. Excessive residual tensile stress leads to cracking of deposited sample, even cause failure to serve. Understanding thermodynamic behavior during processing is critical for controlling residual stress. In this study, in-situ transient strain and temperature gradient evolution of each layer on deposited sample 316L stainless steel thin wall during DED using both continuous-wave (CW) and pulsed-wave (PW) laser modes were emerged by digital image correlation (DIC) method and thermal imager. The longitudinal residual stress of deposited sample was evaluated using two laser modes. The results demonstrated that the PW mode creates a smaller temperature gradient and hence a lesser thermal strain than the CW mode. Furthermore, the cyclic thermal stress characteristics of PW mode was observed. All these factors contribute to the reduction of residual stress. [ABSTRACT FROM AUTHOR]