Jianghui Mao | Oakland University (original) (raw)

Papers by Jianghui Mao

SAE technical paper series, Apr 14, 2015

SAE technical paper series, Mar 29, 2022

The International Journal of Advanced Manufacturing Technology, Jan 28, 2016

It is important to have an accurate description of the mechanical behavior of polymer when predic... more It is important to have an accurate description of the mechanical behavior of polymer when predicting the warpage of injection-molded part. The viscoplastic model for polymer was developed based on the classical Chaboche viscoplastic model for polycrystalline metals. The cyclic tensile test was performed at three levels of strain rate and six levels of temperature. The ratio between Young's modulus in the unloading and loading path was described as function of total strain. The warpage prediction for a plaque has been conducted successfully. The simulated deflection has a good agreement with the measured one by the viscoplastic model for polymer. It also exhibits a significant improvement compared with the simulated one by viscoplastic model for polycrystalline metals.

SAE Technical Paper Series, 2022

International Journal of Damage Mechanics, 2013

The Journal of Strain Analysis for Engineering Design, 2014

This article presents development of a damage-coupled viscoplastic constitutive model with temper... more This article presents development of a damage-coupled viscoplastic constitutive model with temperature consideration. The model is subjected to an explicit nonlocal treatment within the characteristic length that is not limited to one local element as conventional ones. Temperature dependence of material behavior is incorporated into the model to account for the material property degradation at elevated temperature. A test program to determine the correlation between material parameters and temperature is also presented. The nonlocal damage-coupled viscoplastic material model is implemented in a commercial finite element program ABAQUS through its user-defined material subroutine UMAT using a semi-implicit time integration scheme. The model is applied to predict the behavior of 63Sn37Pb soldered structure. The mesh sensitivity of the model is discussed, as well as the efficiency of deduced consistent tangent modulus.

The International Journal of Advanced Manufacturing Technology, 2016

Procedia Engineering, 2015

In this paper, thermomechanical fatigue life (TMF) prediction is performed on an automotive exhau... more In this paper, thermomechanical fatigue life (TMF) prediction is performed on an automotive exhaust manifold using in-house postprocessor code (Hotlife) with four different constitutive models: elastoplastic model with kinematic hardening, two-layer viscoplastic model, and two unified elasto-viscoplastic models based on the equations proposed by Sehitoglu and Chaboche, respectively. Commercial FEA software Abaqus has been used for the analysis. The first two models are already available in Abaqus; the Chaboche and Sehitoglu models were implemented using a user material subroutine (UMAT, available in Abaqus). The stress and strain histories calculated by these four models are output to Hotlife for post-processing. The results from the prediction are then compared to the experimental TMF life obtained from a component thermal fatigue bench test. Result show the Hotlife calculations based on the two implemented elasto-viscoplastic models yield better correlation with test results.

SAE Technical Paper Series, 2015

SAE International Journal of Materials and Manufacturing, 2014

Journal of Engineering Materials and Technology, 2012

A proposed damage model is used for investigating the deformation and interfacial failure behavio... more A proposed damage model is used for investigating the deformation and interfacial failure behavior of an adhesively bonded single-lap thick joint made of S2 glass/SC-15 epoxy resin composite material. The bonding material is 3M Scotch-Weld Epoxy Adhesive DP405 Black. Continuum damage mechanics models are used to describe the damage initiation and final failure at or near the interface. The effect of adhesive overlap length, thickness, and plasticity on the interfacial shear and normal stresses is studied. Experimental and analytical data are used to validate the proposed damage models.

In this paper, the cyclic deformation behavior of an Al-Si-Cu alloy is studied under strain-contr... more In this paper, the cyclic deformation behavior of an Al-Si-Cu alloy is studied under strain-controlled thermo-mechanical loading. Tests are carried out at temperatures from 20 °C to 440 °C. The effect of strain rate, hold time at temperature and loading sequence are investigated at each temperature. The results show that temperature has a significant effect on the cyclic deformation of Al-Si-Cu alloys. With increasing temperature, the effect of strain rate and hold time become more significant, while load sequence effects remain negligible within the investigated temperature range. Thus, an elastoviscoplastic model is required for modeling the alloy's behavior at high temperature. This study provides an insight into the necessary information required for modeling of automotive engine components operating at elevated temperature.

Experimental and numerical investigation of the effect of key joint variables on the static and f... more Experimental and numerical investigation of the effect of key joint variables on the static and fatigue performance of bonded metallic single-lap joints, In this paper, numerical and experimental methods are employed to investigate the effect of surface preparation, adhesive type and thickness, and nanoparticle enrichment on the mechanical performance of bonded metallic single-lap joints. Adherents are made of similar materials; namely, steel-on-steel or aluminum-on-aluminum. Investigated surface preparation variables include roughness and scratch orientation. Adhesive-related variables include thickness, type, and nanoparticle enrichment. Four different commercially available adhesives are investigated, some of which are nanoparticle enriched for the purpose of this study. Static and/or fatigue testing as well as damage analysis-based numerical prediction of joint performance, are provided. Scanning Electron Microscope (SEM) is used for macro joint characterization through the micro observation of joint fracture surfaces. Experimental fatigue data correlates reasonably well with the numerical results obtained from damage-coupled cohesive model of the adhesive layer.

This paper presents an alternative method of material damage evaluation based on the X-ray comput... more This paper presents an alternative method of material damage evaluation based on the X-ray computer tomography-detected microdefects and multiscale computer simulation. This is achieved by developing a method of the digital diagnosis and full-field numerical calculation of material degradation in macroscopic material test specimens. The method comprised three basic components: (a) digital detection and processing of micro/mesoscale material defects of macroscopic material test specimens; (b) multilevel meshing and multilevel finite element analysis for evaluating local/global material degradation; and (c) synchronized experimental and numerical determination of material damage. The unique contributions of the proposed approach include (a) a multilevel finite element meshing and analysis scheme that makes the full-field estimation of material degradation in macroscopic test specimens computationally tractable on regular workstations, (b) full-field exploration of mesoscale material defects (i.e., those with a feature size from several micrometers to a few millimeters), which play a crucial role in failure analysis of engineering components, and (c) the proposed method offers a significantly better accuracy in estimating material degradation in terms of effective modulus than the conventional analytical models in continuum damage mechanics and micromechanics. Test results of aluminum alloys confirm the efficacy of our approach in the digital interrogation of material degradation. Abraham FF, Broughton J, Bernstein N, et al. (1998) Spanning the continuum to quantum length scales in a dynamic simulation of brittle fracture. Europhysics Letters 44(6): 783-787. Belytschko T and Black T (1999) Elastic crack growth in finite elements with minimal remeshing. International Journal for Numerical Methods in Engineering 45(5): 601-620. Brunig M, Albrecht D and Gerke S (2011) Modeling of ductile damage and fracture behavior based on different micromechanisms.

An improved analytical model is proposed for characterizing the fracture behavior of an adhesivel... more An improved analytical model is proposed for characterizing the fracture behavior of an adhesively bonded double cantilever beam joint under Mode I loading. Novel interfacial normal stress distribution function is used with a key parameter c that is determined using continuum mixture theory. In addition to the mechanical and sectional properties of the adherends, crack length, and overlap area, the model also incorporates the adhesive thickness and material properties as well as the crack tip rotation. Model prediction of the fracture toughness of the joint is entered into finite element analysis to simulate crack propagation under peel loading. The effect of various parameters on the joint fracture properties is discussed. Results show that the proposed model provides better correlation with published experimental data.

Composite Materials and Joining Technologies for …

Composite Materials and Joining …