Inverse Determination of Johnson–Cook Parameters of Additively Produced Anisotropic Maraging Steel

In powder bed-based additive manufacturing (AM), complex geometries can be produced in a layer-wise approach. Results of material science experiments regarding material property identification, e.g., tensile strength, show interdependencies between the test load direction and the layer orientation. This goes hand-in-hand with the measured cutting force, changing with the relative angle between cutting direction and layer orientation in orthogonal cutting tests. However, due to the specific process characteristics, the layer orientation results in anisotropic material properties. Therefore, during machining, the material behaves depending on the buildup direction, which influences the cutting process. To predict this behavior, a simplified inverse approach is developed to determine the buildup direction-dependent parameters of a modified Johnson–Cook model for cutting simulation. To qualify these cutting models, mainly the cutting force and additionally the chip formation examined during orthogonal cuts are used. In the present paper, the influence of the laser-powder-bed-fusion (LPBF) process parameters on subtractive post-processing are shown. A good agreement between verification experiments and simulations is achieved.

Supraglacial debris thickness and supply rate in High-Mountain Asia

Supraglacial debris strongly modulates glacier melt rates and can be decisive for ice dynamics and mountain hydrology. It is ubiquitous in High-Mountain Asia (HMA), yet because its thickness and supply rate from local topography are poorly known, our ability to forecast regional glacier change and streamflow is limited. Here we resolved the spatial distribution of supraglacial debris thickness (SDT) for 4401 glaciers in HMA for 2000-2016, via an inverse approach using a new dataset of glacier mass balance. We then determined debris-supply rate (DSR) to 3843 of those glaciers using a debris mass-balance model. Our results reveal high spatial variability in both SDT and DSR, with supraglacial debris most concentrated around Everest, and DSR highest in the Pamir-Alai. We demonstrate that DSR and, by extension, SDT increase with the temperature and slope of debris-supply slopes regionally and that SDT increases as ice flow decreases locally. Our centennial-scale estimates of DSR are an order of magnitude lower than millennial-scale estimates of headwall-erosion rate from 10Be cosmogenic nuclides, indicating that debris supply to the region's glaciers is highly episodic. We anticipate that our datasets will enable improved representation of the complex response of HMA's glaciers to climatic warming in future modelling efforts.

Estimating Relaxation Time and Fractionality Order Parameters in Fractional Non-Fourier Heat Conduction Using Conjugate Gradient Inverse Approach in Single and Three-Layer Skin Tissues

In this work, the relaxation parameter (τ) and fractionality order (α) in the fractional single phase lag (FSPL) non-Fourier heat conduction model are estimated by employing the conjugate gradient inverse method (CGIM). Two different physics of skin tissue are chosen as the studied cases; single and three-layer skin tissues. Single-layer skin is exposed to laser radiation having the constant heat flux of Qin. However, a heat pulse with constant temperature is imposed on the three-layer skin. The required inputs for the inverse problem in the fractional diffusion equation are chosen from the outcomes of the dual phase lag (DPL) theory. The governing equations are solved numerically by utilizing implicit approaches. The results of this study showed the efficiency of the CGIM to estimate the unknown parameters in the FSPL model. In fact, obtained numerical results of the CGIM are in excellent compatibility with the FSPL model.

Using Inverse Transient Statistical Energy Analysis to determine the transient power input from a heavy impact on floating floors

To aid design decision concerning heavy impacts on heavyweight floors, it is necessary to be able to predict Fast-time weighted maximum sound pressure levels (Lp,Fmax) in the receiving room. For excitation directly on the heavyweight floor this can be carried out using Transient Statistical Energy Analysis (TSEA) in a predictive mode. However, the performance of floating floors is not always possible to accurately predict hence an inverse approach to TSEA, referred to as ITSEA, has been developed to determine the transient power. This paper compares the prediction of the Lp,Fmax using TSEA with normalized transient power input determined by ITSEA with measurements conducted in two test chambers with and without floor small floor toppings. For one-third octave bands, the maximum difference in Lp,Fmax between measurement and TSEA ranged from 5.3 to 8.3dB and 6 to 7dB when using W`in,ForcePlate and W`in,ITSEA respectively. For octave bands, the maximum difference in Lp,Fmax between measurement and TSEA ranged from 2.1 to 7.5dB and 2 to 7dB when using W`in,ForcePlate and W`in,ITSEA respectively

Inverse Approach for the Average Convection Coefficient Induced by a Forced Fluid Flow Over an Annular Fin of Rectangular Profile Using Tip Temperature Measurements

The objective of the present paper is to develop a simple algebraic computational procedure for the estimation of the average convection coefficient of a forced fluid flow over an annular fin of rectangular profile within the platform of inverse heat conduction problems. The data required is the tip temperatures of an annular fin of rectangular profile, which are measured in an experimental setup. Based on nonlinear regression analysis, an empirical correlation equation is constructed for the dimensionless average tip temperature depending upon the dimensionless thermo–geometrical parameter and the radius ratio. When compared against the outcome of a direct heat conduction problem, the good quality of the estimated average convection coefficient for the annular fin of rectangular profile demonstrates the feasibility of the simple algebraic computational procedure.