Mechanical Research and Application 

About: Mechanical Research and Application is an academic journal. The journal publishes majorly in the area(s): Ultimate tensile strength & Modal analysis. Over the lifetime, 101 publications have been published receiving 120 citations.

Determination of Tensile Strength and Crack Growth of a Typical Polymer Concrete Using Circular Disc Samples

Abstract: Cracked and un-cracked Brazilian disc specimens subjected to diametral compression were used for conducting fracture toughness and tensile strength experiments on a polymer concrete (PC) material. The value of mode I fracture toughness (KIc) was determined from the centercracked Brazilian disc and the indirect tensile strength ( t) was obtained from the uncracked Brazilian disc specimen. The experiments showed the practical applicability of both cracked and un-cracked specimens for using as suitable techniques for measuring KIc and t in PC materials. The average values of KIc and t of tested PC were about 1.5 MPa m and 8 MPa, respectively which are significantly greater than the corresponding values of KIc and t obtained for conventional cement concrete tested with the same Brazilian disc specimens. Hence, for those structural applications that the risk of tensile rupture and crack growth is high, polymer concretes are more suitable candidates in comparison with the conventional cement concretes.

Load Controlled Fatigue of AZ31B

Abstract: With the expanding demand on application of magnesium alloys in automotive and aerospace industries, robust methods in fatigue characterization of commercially available magnesium alloys with high specific strength is anticipated. In this paper, rotating bending load controlled tests has been studied on specimens machined from an extrusion piece of AZ31B. Due to asymmetric and anisotropic behavior of AZ31B, methods of transferring the load controlled results into stress-life results are lacking. Using the approach of variable material property (VMP), the load-stress relation in fully reversed test is derived. To apply the proposed method to AZ31B, the cyclic behavior of the material is required. Fully reversed step-loading of AZ31B over a wide range of strain amplitude was carried out on a servo hydraulic fatigue rig and was reported in the literature. The stabilized cyclic behavior at half-life was obtained for different load levels. Also, the cyclic tension and the cyclic compression curves were obtained. Using the proposed loadstress model and the actual cyclic behavior of AZ31B, an elastic-plastic solution over the whole domain of cross section was obtained. An energy based fatigue model was then employed to predict the life. The predicted and experimental lives agree well. The proposed method is recommended for correlating the load controlled test with stress and/or strain controlled tests.

Comparison of Compressive Properties Between Va-cuum Infusion and Hand Lay-Up Method Toward Bal-sa Core Sandwich Composites

Abstract: The aim of this work is to evaluate the influence of fabrication methods on the compressive properties of sandwich composites using both experimental work and numerical simulations. Two types of sandwich composites with E-glass/Kevlar/polyester resin facings and Endgrain balsa wood as core have been produced by vacuum infusion processing (VIP) and handlay up (HL) method. Compression tests on sandwich composites showed that the mean values of compressive strength of HL and VIP composites are 15.02 MPa and 28.27 MPa, respectively. The performance of sandwich composites manufactured by VIP are presented and compared to the sandwich composites manufactured by HL method. Based on the experimental tests, VIP appears to produce higher results of sandwich composite compressive properties compared to the HL method. Consequently, in this work, the compressive properties of sandwich composites were characterized by finite element analysis (FEA) and a comparison of the compressive properties in various fabrication methods was then presented. The correspondence between the predicted numerical results and the experiments proves the accuracy of this model.

Creep Behavior of Basalt and Glass Fiber Reinforced Epoxy Composites

Abstract: Basalt fibers enjoy the best potential to be turned into a serious contender in fiber composite market due to its good mechanical properties and favorable costs. The creep behavior of basalt fiber reinforced epoxy (BFRE) and glass fiber reinforced epoxy (GFRE) composites was studied through tensile testing at a high temperature. To study the effect of reinforcing epoxy, the micro glass powder (MGP) was added at various volume percentage into the epoxy resin in BFRE composites. The initial strain for all the specimens were evaluated and compared with each other. No creep rupture failures were observed in short- term (less than 10000 seconds) high temperature (T= 150 and 200 °C) tensile creep tests at the loads up to 15% of the ultimate tensile strength of the specimen. It was also found that the creep resistance of BFRE was higher than that of GFRE and the materials are generally behaved as non-linear for all stresses and temperatures. Adding MGP decreased the initial strain of BFRE, but had no significant effect on the overall life time of BFRE.

Non-Linear Analysis of Viscoelastic Rectangular Plates Subjected to In-Plane Compression

Abstract: Geometrically nonlinear governing equations for a plate with linear viscoelastic material are derived. The material model is of Boltzmann superposi- tion principle type. A third-order displacement field is used to model the shear deformation effects. For the solution of the nonlinear governing equations the Dynamic Relaxation (DR) iterative method together with the finite difference discretization technique is used. Finally, the numerical results for the critical buckling load for simply supported edge constraints are reported. In order to justify the accuracy of the results, the elastic plate critical buckling loads are obtained and compared with the existing results. The correlations are very satisfactory. The numerical results are presented for Classical Plate Theory (CPT), First order- Shear Defonmation Plate Theory (FSDT) and Higher Order- Shear Deformation Plate Theory (HSDT). In the case of thick plate the differences among the three theories are highlighted, however, for thin plate the variations are very small.