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The purpose of this review paper is to provide a review of the most recent advances in the field of manufacturing composite sandwich panels along with their advantages and limitations. The other purpose of this paper is to familiarize the researchers with the available developments in manufacturing sandwich structures.

The most recent research articles in the field of manufacturing various composite sandwich structures were reviewed. The review process started by categorizing the available sandwich manufacturing techniques into nine main categories according to the method of production and the equipment used. The review is followed by outlining some automatic production concepts toward composite sandwich automated manufacturing. A brief summary of the sandwich manufacturing techniques is given at the end of this article, with recommendations for future work.

It has been found that several composite sandwich manufacturing techniques were proposed in the literature. The diversity of the manufacturing techniques arises from the variety of the materials as well as the configurations of the final product. Additive manufacturing techniques represent the most recent trend in composite sandwich manufacturing.

This work is valuable for all researchers in the field of composite sandwich structures to keep up with the most recent advancements in this field. Furthermore, this review paper can be considered as a guideline for researchers who are intended to perform further research on composite sandwich structures.

Auxetic sandwich structures are gaining attention because of the negative Poisson’s ratio effect offered by these structures. Re-entrant core was one configuration of the auxetic structures. There is a growing concern about the design and behavior of re-entrant cores in aerospace, marine and protection applications. Several researchers proposed various designs of re-entrant core sandwiches with various materials. The purpose of this study is to review the most recent advances in re-entrant core sandwich structures. This review serves as a guide for researchers conducting further research in this wide field of study.

The re-entrant core sandwich structures were reviewed in terms of their design improvements, impact and quasi-static crushing responses. Several design improvements were reviewed including 2D cell, 3D cell, gradient, hierarchical and hybrid configurations. Some common applications of the re-entrant core sandwiches were given at the end of this paper with suggestions for future developments in this field.

Generally, the re-entrant configuration showed improved energy absorption and impact response among auxetic structures. The main manufacturing method for re-entrant core manufacturing was additive manufacturing. The negative Poisson’s ratio effect of the re-entrant core provided a wide area of research.

Generally, re-entrant cores were mentioned in the review articles as part of other auxetic structures. However, in this review, the focus was solely made on the re-entrant core sandwiches with their mechanics.

This paper aims to provide a comprehensive review of the state-of–the-art design methods for additive manufacturing (AM) technologies to improve functional performance.

In this survey, design methods for AM to improve functional performance are divided into two main groups. They are design methods for a specific objective and general design methods. Design methods in the first group primarily focus on the improvement of functional performance, while the second group also takes other important factors such as manufacturability and cost into consideration with a more general framework. Design methods in each groups are carefully reviewed with discussion and comparison.

The advantages and disadvantages of different design methods for AM are discussed in this paper. Some general issues of existing methods are summarized below: most existing design methods only focus on a single design scale with a single function; few product-level design methods are available for both products’ functionality and assembly; and some existing design methods are hard to implement for the lack of suitable computer-aided design software.

This study is a useful source for designers to select an appropriate design method to take full advantage of AM.

In this survey, a novel classification method is used to categorize existing design methods for AM. Based on this classification method, a comprehensive review is provided in this paper as an informative source for designers and researchers working in this field.

This chapter describes a service learning (SL) project implemented in an upper-level undergraduate Cost Accounting course to enhance the coverage of costing concepts. Employing a variation of Lafond, Leauby, and Wentzel (2017) SL task, students actively gather cost data for a business venture by preparing peanut butter and jelly sandwiches which are then donated to a local soup kitchen. Comparison of scores on pre- and post-tests suggests that the SL assignment enhances students’ understanding of key cost accounting concepts. More specifically, improvements in mean post-test scores proved significantly greater in the experimental group after completion of the SL activity than in the control group. Feedback further suggests that students appreciated the opportunity to engage in SL by helping others less fortunate. Active SL tied to course objectives meets The Association to Advance Collegiate Schools of Business (AACSB, 2013) suggestions for honing students’ critical thinking skills, while also helping to instill SL values in future business leaders.

The purpose of this study was to introduce three-dimensional printing (3DP) of functionally graded sandwich foams (FGSFs). This work was continued by predicting the mechanical buckling and free vibration behavior of 3DP FGSFs using experimental and numerical analyses.

Initially, hollow glass microballoon-reinforced high-density polyethylene-based polymer composite foams were developed, and these materials were extruded into their respective filaments. These filaments are used as feedstock materials in fused filament fabrication based 3DP for the development of FGSFs. Scanning electron microscopy analysis was performed on the freeze-dried samples to observe filler sustainability. Furthermore, the density, critical buckling load (P_cr), natural frequency (f_n) and damping factor of FGSFs were evaluated. The critical buckling load (P_cr) of the FGSFs was estimated using the double-tangent method and modified Budiansky criteria.

The density of FGSFs decreased with increasing filler percentage. The mechanical buckling load increased with the filler percentage. The natural frequency corresponding to the first mode of the FGSFs exhibited a decreasing trend with an increasing load in the pre-buckling regime and an increase in post-buckled zone, whereas the damping factor exhibited the opposite trend.

The current research work is valuable for the area of 3D printing by developing the functionally graded foam based sandwich beams. Furthermore, it intended to present the buckling behavior of 3D printed FGSFs, variation of frequency and damping factor corresponding to first three modes with increase in load.

Sandwich construction with aluminium honeycomb cores bonded to faces with the adhesive films Redux 775, 775R and Bloomingdale FM‐47 is discussed. Drawings showing its applications to a series of components for various hypothetical aircraft arc included. Sandwich materials for supersonic aircraft of the types now entering production are reviewed, as well as the application techniques of the new Redux films. Some rules gathered from experience for the design of components with honeycomb cores, and solutions of special design problems with hypothetical wing panels, are treated. The paper then deals fairly fully with results from a programme of FFA investigations on this type of structure. The specimens discussed were bonded with Redux 775 and FM‐47 and consisted partly of tensile tests on cores, compressive tests on sandwich columns and shear tests on various sandwich webs. Design curves have been plotted in some cases. Further results are presented showing the influence of temperature on the shear strength of an aluminium alloy core and Redux 775 and FM‐47 films. Also a few creep results are given where the object of the tests has been to determine the optimum curing temperature and time for applying Redux 775 to yield minimum creep values. The room‐temperature results illustrate the excellent properties of honeycomb structures and the elevated‐temperature results indicate that bonded uninsulated aluminium sandwiches can be retained, even when the temperature due to kinetic heating approaches 70 deg. C. Finally, some remarks regarding future developments are made on various new ‘temperature‐resistant’ adhesives and on combinations of various materials for sandwich panels with external insulation, suitable for certain types of the next breed of supersonic aircraft.

The purpose of this paper is to develop a general mathematical model for the evaluation of the bending and vibration responses of the skew sandwich composite plate using higher-order shear deformation theory. The sandwich structural components are highly preferable in modern engineering application because of their desirable structural advantages despite the manufacturing and analysis complexities. The present model is developed to solve the bending and vibration problem of the skew sandwich composite plate with adequate accuracy numerically in the absence of the experimental analysis.

The skew sandwich composite plate structure is modelled in the present analysis by considering laminated face sheet in conjunction with isotropic and/or orthotropic core numerically with the help of the higher-order mathematical model. Further, the responses are computed numerically with the help of in-house computer code developed in matrix laboratory (MATLAB) environment in conjunction with finite element (FE) steps. The system governing equations are derived via variational technique for the computation of the static and the frequency responses.

The skew sandwich composite plate is investigated using the higher-order kinematic model where the transverse displacement through the thickness is considered to be linear. The convergence and the validation study of the bending and the frequency values of the sandwich structure indicate the necessary accuracy. Further, the current model has been used to highlight the applicability of the higher-order kinematics for the evaluation of the sandwich structural responses (frequency and static deflections) for different design parameters.

In the present paper, the bending and the vibration responses of the skew sandwich composite plate are analysed numerically using the equivalent single-layer higher-order kinematic theory for the isotropic and the orthotropic core numerically with the help of isoparametric FE steps. Finally, it is understood that the present model is capable of solving the sandwich structural responses with less computation cost and adequate accuracy.

Understanding the effect of process parameters on interfaces and interfacial bonding between two materials during multi-material additive manufacturing (MMAM) is crucial to the fabrication of high-quality and strong multi-material structures. The purpose of this paper is to conduct an experimental and statistical study to investigate the effect of process parameters of soft and hard materials on the flexural behavior of multi-material structures fabricated via material extrusion-based MMAM.

Sandwich beam samples composed of a soft core and hard shells are fabricated via MMAM under different printing conditions. A design of experiments is conducted to investigate the effect of the print speed and nozzle temperature on the flexural behavior of soft-hard sandwich beams. Analysis of variance and logistic regression analysis are used to analyze the significance of each process parameter. The interfacial morphology of the samples after the flexural tests is characterized. Thermal distributions during the MMAM process are captured to understand the effect of process parameters on the flexural behavior based on inter-bonding formation mechanisms.

Experimental results show that the soft-hard sandwich beams exhibited two different failure modes, including shell failure and interfacial failure. A transition of failure modes from interfacial failure to shell failure is observed as the nozzle temperatures increase. The samples that fail because of interfacial cracking exhibit a pure adhesive failure because of weak interfacial fracture properties. The samples that fail because of shell cracking exhibit a mixed adhesive and cohesive failure. The flexural strength and modulus are affected by the nozzle temperature for the hard material and the print speeds for both hard and soft materials significantly.

This paper first investigates the effect of process parameters for soft and hard materials on the flexural behavior of additively manufactured multi-material structures. Especially, the ranges of the selected process parameters are distinct, and the effect of all possible combinations of the process parameters on the flexural behavior is characterized through a full factorial design of experiments. The experimental results and conclusions of this paper provide guidance for future research on improving the interfacial bonding and understanding the failure mechanism of multi-material structures fabricated by MMAM.

The incipient growth of the fused deposition modeling (FDM) techniques encourages the development of models to predict the behavior of these parts involving complicated and heterogeneous geometries whose behavior strongly diverges from the continuous model hypothesis. This paper aims to address the problem of predicting the flexural properties of FDM parts building on the geometrical similarity between a typical FDM part and a sandwich panel.

This paper takes advantage of the morphological similarity between FDM structures and composite sandwich panels. Thus, an approach based on classic sandwich theory is developed to validate its goodness to predict the flexural behavior of FDM parts. A set of tensile and flexural tests for FDM parts were conducted varying the density of the core pattern (10%, 15%, 20% and 25%), being the proposed model and the predicted results validated.

The results showed a good accordance between the predicted values of stiffness and the experimental data. Although this is especially evidenced for low infill density values, for densities above 20% the experimental values noticeably exceed the maximum predicted stiffness, which can be explained by the non-compliance of the foil honeycomb hypothesis for high-density patterns. The main implication of these findings lies in the possibility of using advanced models from thin-foil structures as a base to develop accurate analytical approaches to model FDM structures.

Although the experimental characterization of FDM parts has been a matter of study in the literature, the development of robust theoretical models that consider the influence of the particular morphology of these parts is still a challenge in this field. The approach proposed in this study constitutes the first step to develop a complete analytical model to predict the complex behavior of FDM printed parts.

The aim of this study is to perform a comparative study on sandwich structures with several types of three-dimensional (3D) reticulate cellular structural core designs for their low-energy impact absorption abilities using powder bed additive manufacturing methods. 3D reticulate cellular structures possess promising potentials in various applications with sandwich structure designs. One of the properties critical to the sandwich structures in applications, such as aerospace and automobile components, is the low-energy impact performance.

Sandwich samples of various designs, including re-entrant auxetic, rhombic, hexagonal and octahedral, were designed and fabricated via selective laser sintering (SLS) process using nylon 12 as material. Low-energy drop weight test was performed to evaluate the energy absorption of various designs. Tensile coupons were also produced using the same process to provide baseline material properties. The manufacturing issues such as geometrical accuracy and anisotropy effect as well as their effects on the performance of the structures were discussed.

In general, 3D reticulate cellular structures made by SLS process exhibit significantly different characteristics under low-energy drop weight impact compared to the regular extruded honeycomb sandwich panels. A hexagonal sandwich panel exhibits the largest compliance with the smallest energy absorption ability, and an octahedral sandwich panel exhibits high stiffness as well as good impact protection ability. Through a proper geometrical design, the re-entrant auxetic sandwich panels could achieve a combination of high energy absorption and low response force, making it especially attractive for low-impact protection applications.

There has been little work on the comparative study of the energy absorption of various 3D reticulate cellular structures to date. This work demonstrates the potential of 3D reticulate cellular structures as sandwich cores for different purposes. This work also demonstrates the possibility of controlling the performance of this type of sandwich structures via geometrical and process design of the cellular cores with powder bed additive manufacturing systems.