Stretch forming studies on a fibre metal laminate based on a self-reinforcing polypropylene composite

This paper investigates the room temperature formability of a fibre metal laminate system comprised of aluminium and a self-reinforcing polypropylene composite. Blanks of varying geometry were stretch formed over a hemispherical punch in a custom built stamping press. A real-time three-dimensional photogrammetric measuring system was used to acquire the evolution of surface strain and the strain at failure during forming. The results from this work illustrate that these advanced light weight material systems are amenable to mass production through stamp forming. A significant finding from this work is that these material systems can exhibit forming characteristics that are comparable and sometimes superior to metal forming

The Influence of Strain Rate on the Mode III Interlaminar Fracture of Composite Materials

The Mode III interlaminar fracture toughness, GIIIc, of composite materials based on both thermoplastic and thermosetting-matrices have been investigated using the edge crack torsion (ECT) test geometry. Tests were undertaken at room temperature and ove

Towards a rapid, non-contact shaping method for fibre metal laminates using a laser source

Abstract Since their initial development, fibre metal laminates (FMLs) have slowly started to be used by industry, particularly the aerospace sector. One of the reasons for the relatively slow adoption of FMLs is due to the difficulties faced in shaping them to the desired geometry. Whilst traditional processes such as roll forming are effective in shaping monolithic materials, these processes could potentially destroy the mechanical properties of the composite layer. The approached investigated here uses thermal or laser forming (LF) to shape flat panels of thermosetting glass fibre based FMLs into 2D geometries. This initial empirical investigation covers the effectiveness of the various LF processes and the effects of various parameters have on the forming process. These include laser parameters such as power and velocity and material parameters such as FML lay-up strategy, fibre orientation and comparison with monolithic materials

Tapping a Foreign Subsidiarys Competence: An Empirical Test of Subsidiaries of Multinational Corporations in South Korea

This study examined the conditions under which a foreign subsidiary becomes the competence center within the multinational corporation (MNC)s network. We developed an integrated framework by investigating effects of both subsidiary-level factors and headquarter (HQ)-level factors on subsidiarys competence development. Survey data from 76 foreign subsidiaries of MNCs in South Korea largely supported our hypotheses. We found that subsidiaries with high management autonomy and high network embeddedness in the local market (South Korea) tend to build superior capabilities that would be useful throughout the entire MNC network. Concerning an MNCs management system, our results suggested that technological and managerial knowledge transfer from HQ to subsidiaries plays important roles in helping a subsidiary evolve into a competence center in the MNCs global network

Influence of loading rate on the interfacial fracture toughness of a polyamide-based fiber-metal laminate

The effect of loading rate on the interfacial fracture toughness of a glass-fiber/polyamide fiber-metal laminates (FMLs) was studied. Impact testing was conducted at 3 m/s using a drop weight impact machine with a striker of mass 2.6 kg. Overall, although the results and differences in failure mode suggest a viscoelastic response in the film adhesive, the outcome is a positive effect on the interfacial fracture toughness

Additively manufactured cylindrical systems with stiffness-tailored interface: Modeling and experiments

The structural performance of multi-material bonded systems can be significantly improved by tailoring interfaces. Here, we report the performance of cylindrical bonded systems with stiffness-tailored interface both experimentally enabled by 3D printing, as well as by modeling. Stiffness-tailored systems are additively manufactured by engineering edge-compliance into the bondlayer. The deformation and failure behavior of 3D printed shaft-tube joints with such stiffness-tailored bondlayer was evaluated experimentally under axial tensile loads and was found to have about 40% and 25% more load carrying capacity and toughness, respectively, compared to joints with homogeneous bondlayer. A linear-elastic finite element (FE) model benchmarked with experimental results was employed to examine how the stress redistribution in the bondlayer due to stiffness-tailoring led to improved performance of graded joints. Motivated by the superior performance of stiffness-tailored joints, an analytical model for such joints is proposed within the purview of axisymmetric linear elastostatics. The effect of smoothly grading the interface properties of 3D printed shaft-tube joints on stress distribution is investigated and the influence of grading on shear-transfer length is identified using the developed model considering power-law variation of bondlayer’s modulus along bondlength. A reduction in peak shear stress of about 45% was observed for systems with bondlength (l) greater than the shear-transfer length (lcri) i.e., l ≥ lcri for relatively stiff bondlayers. Subsequently, the stresses in more general class of bonded systems comprising metallic adherends and epoxy adhesive with power-law and exponential gradation schemes were analyzed. These gradation schemes were found to have a significant influence on stress redistribution along the bondlength of the adhesive providing guidelines for the optimal design of stiffness-tailored high performance bonded systems