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As additive manufacturing (AM) is currently used for fabrication of end-use products, different methods have been developed to decrease surface roughness of three-dimensional (3D)-printed parts. In this study, a series of experimental tests was performed to investigate influence of post-processing on the fracture behavior of 3D-printed polymer components. To this aim, acrylonitrile butadiene styrene (ABS) material was used to print dog-bone shaped and semi circular bending (SCB) specimens based on fused deposition modeling process. The surface treatment of 3D-printed ABS parts was conducted by immersing the test coupons into acetone solution. The dog-bone shaped specimens printed with different raster directions were examined to determine basic mechanical properties before and after surface treatment. A series of three-point bending tests was carried out on untreated and treated SCB specimens to investigate their structural performance and fracture behavior. Moreover, digital image correlation technique was used to track the fracture process and study the strain fields of the SCB specimens. The fracture toughness of untreated and treated specimens under mode I are determined. Although dipping 3D-printed parts into acetone solution improve the surface finish of the parts, the fracture toughness was reduced from 2.62 MPa m to 2.49 MPa m. Additionally, three-point bending tests on SCB specimens proved that the performed surface treatment changed the fracture growth path in 3D-printed ABS parts. [ABSTRACT FROM AUTHOR]

Due to the wide scope of applications of additive manufacturing (AM) in making final products, the mechanical strength of AM parts has become very important. Therefore, different tests are being developed to determine the structural integrity of three-dimensional printed components. In this respect, the pin-bearing test is designed to evaluate the response of a fastener, plate, and hole to stress. In this study, two different polymer materials were used to fabricate the samples utilizing the fused deposition modeling technique. Since the specimen width and hole diameter have effects on the pin-bearing strength and structural integrity of the parts, we prepared the specimens with four hole diameters to determine the influence of this ratio. A series of tensile tests were performed, and the stiffness and pin-bearing strength of additively manufactured specimens were determined. The preferred bearing failure mode was observed in several tested specimens. Subsequently, a scanning electron microscope investigation was conducted on the damaged area of the examined specimens to obtain insights into the damage mechanisms and failure behavior of the aforementioned specimens. We used digital image correlation technique to determine the strain field of dumbbell-shaped test coupons. The results of this research can be utilized for new designs of AM parts with a higher mechanical strength. [ABSTRACT FROM AUTHOR]

Considering wide applications of Additive Manufacturing (AM), profound knowledge on the mechanical performance of AMed components is a necessity. In the present study, the mechanical behavior of AMed polymer parts under static and dynamic tests has been investigated. To this end, cantilever beams with three different mesostructure cells were designed and fabricated via ABS Carbon material based on the fused deposition modeling process. The specimens were subjected to a series of static bending tests and free vibration experiments. In addition, numerical models have been presented for both static bending and the dynamic tests. In the current study, digital image correlation technique has been employed to determine strain field and validate the numerical results. The experimental findings and numerical outcomes have been compared and the convergence has been investigated. Based on the applications of AM in fabrication of structural elements with complex geometries, the results of the current study are useful for new designs of AMed parts with customized mechanical strength and enhanced structural performance. • Fabrication of beam-like specimens with different mesostructures are explained. • In experimental part, static bending tests and free vibration experiments are conducted. • Numerical models have been presented for both static bending and the dynamic tests. • The comparison of experimental findings and numerical outcomes is documented. [ABSTRACT FROM AUTHOR]

In the present study, the fracture behavior of additively manufactured (AM) metal parts has been investigated. To this aim, double edge notch tension (DENT) specimens have been printed using AlSi10Mg alloy based on the laser powder bed fusion (PBF) technique. Particularly, DENT specimens have been fabricated with three different ligament lengths and three different printing directions for each ligament length. In this study, we used the concept of essential work of fracture to describe the fracture behavior AMed parts. According to a series of tests under static loading conditions, influences of the ligament length and printing direction on the structural integrity of the DENT specimens have been determined. According to the experimental practices, levels of ductility and size of plastic zone in the ligament region have been documented. Here, we utilized digital image correlation technique to measure strain fields on the surface of the examined samples. Moreover, numerical simulations have been conducted to simulate the stress distribution from DENT specimens. In addition, visual inspection of the fracture surfaces has been conducted using a free-angle observation system. The outcome of this study can be used for future designs of PBF printed parts with a better structural performance. [ABSTRACT FROM AUTHOR]

Since additive manufacturing (AM) has been utilized for production of functional end-use parts, the mechanical behavior of the additively manufactured parts is a crucial issue. In the present study, compact tension (CT) test is conducted on 3D-printed polymer parts which are fabricated based on the fused deposition modeling (FDM) technique. Considering the influence of the printing parameters on the mechanical performance of the parts, the specimens are fabricated under different printing parameters. In detail, CT specimens are printed with +45°/−45° and 0°/90° filament directions and 0.2 and 0.5 mm layer thicknesses at printing speed of 20 mm/s and 70 mm/s. Based on the CT tests, the fracture behavior of the parts are investigated and their fracture toughness are determined. In addition, digital image correlation technique is used to determine the strain fields on the surface of the CT specimens. Moreover, a series of finite element analysis is performed to study the mechanical behavior of modeled parts. Additionally, scanning electron microscopic investigation is performed for visual examination of the fractured components. According to the results, optimum printing parameters for maximizing the mechanical properties are determined. Due to the wide applications of the FDM 3D-printed parts, the documented results are beneficial for fabrication of parts with a higher mechanical strength. [ABSTRACT FROM AUTHOR]

• Fracture of pre-cracked Semi-Circular Bending is investigated. • Plastic flow at crack tip is measured using Digital Image Correlation (DIC) technique. • Accumulated entropy up to fracture is related to materials interatomic debonding strength. • Fracture occurs when accumulated entropy exceeds a unique threshold. The accumulated entropy at the crack tip of a semi-circular bending (SCB) specimen is investigated to obtain a threshold for material fracture and interatomic debonding. The presented approach uses the experimental data obtained from the Digital Image Correlation (DIC) technique and strain maps superposed to SCB specimens to measure the plastic flow at the crack tip. The Swift strain hardening model is utilized to calculate the stress domain at the crack tip and, consequently, the plastic strain energy and entropy accumulation. Results show that the crack surface propagates when the generated entropy at the crack tip reaches a critical limit. This critical value can be considered as the material capacity beyond which bond breakage occurs. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM), typically known as three-dimensional (3D) printing has paved the way for fabrication of individualized products. Since 3D-printed composites show a superior strength to weight ratio, their applications have significantly increased. In the current study, fracture behavior of 3D-printed fiber-reinforced composites and steel specimens was determined and compared. Particularly, the Fused Filament Fabrication (FFF) process was used to print Semi-Circular Bending (SCB) composite specimens. In this context, nylon and glass fibers were used as matrix and fiber reinforced materials, respectively. Moreover, steel SCB specimens were fabricated and examined for comparison. All specimens were subjected to three-point bending and their mechanical behavior was examined. In this study, Digital Image Correlation (DIC) technique was utilized to measure strain on the surface of the specimen. In addition, a numerical simulation was performed to study fracture load of SCB steel specimens and verify experimental observations. The outcome of this study indicates that structural integrity of SCB specimens increases with fiber volume fraction. The documented results can be used for design, optimization, development, and simulation of 3D-printed continuous glass fiber-reinforced composites. • Unreinforced and reinforced 3D-printed composites were fabricated. • A series of experiments on semi-circular bending specimens was performed. • Fracture behavior of 3D-printed parts with different fiber contents was investigated. • The presented data can be used for optimal design of reinforced 3D-printed composites. [ABSTRACT FROM AUTHOR]