Geometrically nonlinear polygonal finite element analysis of functionally graded porous plates

In this study, an efficient polygonal finite element method (PFEM) in combination with quadratic serendipity shape functions is proposed to study nonlinear static and dynamic responses of functionally graded (FG) plates with porosities. Two different porosity types including even and uneven distributions through the plate thickness are considered. The quadratic serendipity shape functions over arbitrary polygonal elements including triangular and quadrilateral ones, which are constructed based on a pairwise product of linear shape functions, are employed to interpolate the bending strains. Meanwhile, the shear strains are defined according to the Wachspress coordinates. By using the Timoshenko's beam to interpolate the assumption of the strain field along the edges of polygonal element, the shear locking phenomenon can be naturally eliminated. Furthermore, the C0–type higher-order shear deformation theory (C0–HSDT), in which two additional variables are included in the displacement field, significantly improves the accuracy of numerical results. The nonlinear equations of static and dynamic problems are solved by Newton–Raphson iterative procedure and by Newmark's integration scheme in association with the Picard methods, respectively. Through various numerical examples in which complex geometries and different boundary conditions are involved, the proposed approach yields more stable and accurate results than those generated using other existing approaches

Analysis and control of geometrically nonlinear responses of piezoelectric FG porous plates with graphene platelets reinforcement using B\'ezier extraction

In this study, we propose an effective numerical approach to analyse and control geometrically nonlinear responses for the functionally graded (FG) porous plates reinforced by graphene platelets (GPLs) integrated with piezoelectric layers. The basis idea is to use isogeometric analysis (IGA) based on the B\'ezier extraction and the $C^0$-type higher-order shear deformation theory ($C^0$-HSDT). By applying the B\'ezier extraction, the original Non-Uniform Rational B-Spline (NURBS) control meshes can be transformed into the B\'ezier elements which allow us to inherit the standard numerical procedure like the finite element method (FEM). The mechanical displacement field is approximated based on the $C^0$-HSDT whilst the electric potential is assumed to be a linear function through the thickness of each piezoelectric sublayer. The FG plate contains the internal pores and GPLs dispersed in the metal matrix either uniformly or non-uniformly according to various different patterns along the thickness of plate. In addition, to control dynamic responses, two piezoelectric layers are perfectly bonded on the top and bottom surfaces of the FG plate. The geometrically nonlinear equations are solved by the Newton-Raphson iterative procedure and the Newmark's time integration scheme. The influences of the porosity coefficients, weight fractions of GPLs as well as the external electrical voltage on the geometrically nonlinear behaviours of the plates with different porosity distributions and GPL dispersion patterns are evidently investigated through numerical examples. Then, a constant displacement and velocity feedback control approaches are adopted to active control the geometrically nonlinear static as well as the dynamic responses of the FG porous plates, where the effect of the structural damping is considered, based on a closed-loop control with piezoelectric sensors and actuators.Comment: 39 pages, 20 figure

Political Corruption and Mergers and Acquisitions

This research examines the relation between political corruption and mergers and acquisitions (M&As). We find that local corruption increases firm acquisitiveness but decreases firm targetiveness. The levels of corruption in acquirer areas relate positively to the bid premiums and negatively to the likelihood of deal completion. Corruption motivates acquiring firms to use excess cash for payment, which mitigates the negative effect of corruption on acquirer shareholder value. The evidence indicates that acquisitions help acquiring firms convert cash into hard-to-extract assets and relocate assets from the high to low corruption areas, thereby shielding their liquid assets from expropriation by local officials

Policy Uncertainty and Firm Cash Holdings

This research examines the relation between government economic policy uncertainty and firm cash holdings. We find evidence that policy uncertainty is positively related to firm cash holdings due to firms’ precautionary motives and, to a lesser extent, investment delays. The relation between policy uncertainty and cash holdings is more pronounced for firms dependent on government spending and extends beyond business cyclicality. Further analysis indicates that the effects of policy uncertainty on corporate cash holdings are distinct from those of political, market, or other macroeconomic uncertainty

Shareholder Litigation Rights and Capital Structure Decisions

We exploit the staggered adoption of the universal demand (UD) laws across U.S. states, which impedes shareholder rights to initiate derivative lawsuits, as a quasi-natural experiment to examine the relation between shareholder litigation rights and firm capital structures. We find that weaker shareholder litigation rights due to the UD laws adoption lead to higher financial leverage, which enhances firm value. Furthermore, the positive relation between the UD laws adoption and financial leverage is more pronounced for firms exposed to higher shareholder litigation risk ex ante or financially constrained firms. Our evidence is consistent with lower shareholder litigation threats motivating firms to increase financial leverage

Midair Refueling for Sensation Seeking? Pilot CEOs and Corporate Debt Contracting

We examine the relation between chief executive officer (CEO) sensation seeking, which captures the desire for varied, novel, and complex personal sensations and experiences, and corporate debt contracting. Using pilot certificates as a proxy for the personality trait of sensation seeking, we find that firms with pilot CEOs use longer maturity debt financing even when long-term debt is more costly than short-term debt. Our findings are robust to controlling for the endogenous matching between firms and CEOs. Our evidence indicates that CEOs with sensation-seeking personality traits prefer long-term debt financing to avoid the liquidity risk associated with short-term debt financing that may hamper other corporate activities motivated by their sensation seeking

Political Corruption and Corporate Risk-Taking

We use variation in corruption convictions across judicial districts in the US to examine the relationship between political corruption and risk-taking of public firms. Firms headquartered in regions with high levels of political corruption have lower total risk and lower idiosyncratic risk on average. Further analysis shows that corruption tends to encourage firms to pursue risk-decreasing investments, lower the riskiness of their operations, and decrease asset liquidity. While managerial ownership is intended to align the interests of managers and shareholders, the presence of corruption appears to encourage undiversified managers to decrease risk-taking. Our evidence is consistent with agency theory and the asset-shielding argument that political corruption discourages managers from taking risks that expose firms to expropriation by politicians, resulting in suboptimal corporate policies