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ichwan zuardy

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Papers by ichwan zuardy

Apparatus and Method for Producing a Component and Aircraft Structure Component

Investigation of Impact Behavior of sandwich structures with reinforced foam cores (Untersuchung des Impactverhaltens von CFK-Sandwichstrukturen mit verstaerkten Schaumkernen)

German Aerospace Congress 2010, 2010

Foam core sandwich structures with CFRP skin layers show excellent properties in terms of product... more Foam core sandwich structures with CFRP skin layers show excellent properties in terms of production and lightweight capability for application in the primary structures of aircraft. Their damage tolerance behavior, in particular the insufficiently understood impact behavior, is a hinder for that purpose. Reinforced foam core system shows a promising way to improve these properties, with the focus on the investigation of damage growth in the foam core or the interface zone. Applications in primary structures also require a good understanding of the source of damage under e.g. a shock load as well as a the growth behavior and the influencing mechanisms. Dynamic loads such as impact one can be simulated numerically using the explicit finite element method. Sandwich structures with reinforced foam cores are a particular challenge. This is due to a significantly increased modeling effort, which leads to the question of whether a discrete or a homogenized modeling of the reinforcement elements is used, and to correspondingly longer computing times. In the case of a global model with a corresponding structural response, homogenized modeling appears to be sufficient, while in the case of more local models for examining e.g. Damage mechanisms a discrete modeling of the reinforcement elements is necessary. In this work different modeling and analysis approaches for reinforced foam core systems are briefly discussed and finally a modeling approach is presented. The focus is on the application of these models to describe the impact behavior by means of explicit, numerical simulation. A further application of the same approaches for the investigation of e,g, quasi static or transient thermo-mechanical problems is conceivable.

Impact Damage Resistance of CFRP Foam Core Sandwich Panels

10th International Conference on Sandwich Structures (ICSS10) in Nantes, France, August 2012, 2012

Sandwich structures with face sheets made of carbon fiber reinforced plastics (CFRP) demonstrate ... more Sandwich structures with face sheets made of carbon fiber reinforced plastics (CFRP) demonstrate a high potential to reduce both production costs and the weight of primary aircraft structures. This potential has however yet not been realized mainly due to the complex structural and material behavior of sandwich structures under different kinds of loading and adverse effects like moisture take up of honeycomb core material [1]. Using closed cell hard foams such as PMI foam, better known as Rohacell®, the issue of moisture take-up has been solved. One more critical issue however is the often criticized lack of damage tolerance of sandwich structures [2].
Impact damage resistance is part of the larger topic of damage tolerance. It can be treated separately as impacts may cause a damage that is used a starting point for a damage tolerance analysis while not vice versa. In consequence the resulting damage size of a predefined impact scenario is of great importance.

Advanced numerical investigation of the impact behavior of CFRP foam core sandwich structures

Conference: 3rd ECCOMAS Thematic Conference on the Mechanical Response of Composites, 2011

Sandwich structures with face sheets made of carbon fibre reinforced plastics (CFRP) have a hig... more Sandwich structures with face sheets made of carbon fibre reinforced plastics (CFRP) have a high potential in reducing production costs and weight of primary aircraft structures. Their advantage is based on their superior bending stiffness compared to solid laminates. This allows a less complex and highly integrated structural design which typically reduces the number of parts and joints significantly. The highlighted potential has however yet not been realized within primary aircraft structures mainly due to the complex structural behaviour. Another adverse effect often mentioned is moisture take up of the core material. Using closed cell hard foams such as PMI foam, better known as Rohacell®, for the core, the problem of moisture take-up has been solved. Damage tolerance however has been one of the most critical issues regarding the use of sandwich structures [1] [2]. Extensive research has been conducted on CFRP foam core sandwich structures with mostly PVC foam for application in marine vessels, which provides a large benefit for today’s level of understanding. Past and current research concentrates on describing material behaviour with damage, damage growth under cyclic loading and consequently maximum damage sizes [3]-[5]. Less attention has however been given to damage initiation by localized impact events. Low Velocity impact may lead to face sheet
and/or core damages [6]-[8].

Application Potential of a Bionic Optimized Design in the Aerospace (Anwendungspotential einer nach dem Vorbild der Natur Strukturoptimierten Bauweise in der Luftfahrt)

German Aerospace Congress 2011, 2011

The development of aircraft has imitated in many facets the natural flight behavior of the flying... more The development of aircraft has imitated in many facets the natural flight behavior of the flying animal. As with the slenderness shape of the bird's wings mainly determined the aerodynamic performance of an aircraft as well as the wing lets.

This paper discusses the application potential of the other design model in the nature, the plant stem, in the aviation structure. This natural fiber composite structure is built with low material and energy need, but, can achieve amazing mechanical performances. The suitable manufacturing technology, a combination of braiding and pultrution, as well as the application in the primary structures of aircraft are further discussed.

Sandwich Structures Technology in Commercial Aviation - Present Applications and Future Trends

ICCS7: Advancing with Sandwich Structures and Materials (Springer Netherland), Aug 31, 2005

This paper gives a brief overview of sandwih application history in general and present composite... more

An advanced centre box of a vertical tail plane with a side panel from composite foam core sandwich structure

CEAS Aeronautical Journal, Aug 25, 2011

Despite its superior specific stiffness, the sandwich design is currently applied in commercial a... more Despite its superior specific stiffness, the sandwich design is currently applied in commercial aviation mainly in secondary structures. A major reason for this is its low resistance to a concentrated out-of-plane load, such as impact loading by a foreign object. In this scenario, the resulting damage is also known as foreign object damage and may penetrate further into the sandwich core. An improvement of impact resistance shall be achieved to introduce sandwich into the primary structures. Within the German aeronautics research programme, a primary sandwich structure, i.e. the centre box for a next generation vertical tail plane, was developed. The geometrical characteristics of the sandwich shell of the box, which has a unique lens shaped or lenticular cross section, lead to a noticeable improvement of its impact resistance. The considered sandwich configuration consists of carbon-fibre reinforced plastic skins and a closed cell foam core in between, which allows manufacturing using liquid composite moulding, such as a vacuum assisted infusion process. Embedded core reinforcements and damage arresters, respectively, can be manufactured within the same process step. Furthermore, the developed novel aircoupled ultrasonic scanning can detect the manufacturing flaws contact-freely as well as impact damages and thus enhances the inspection and damage tolerance capability of the sandwich structure. For the proof of structural integrity, a cutout in the critical area of the sandwich panel was defined and modified, such that it has no significant eccentricity and fits into an available shear-compression test facility. Loads are increased stepwise to explore all structural responses including interactions. The results show excellent structural stability with respect to the damage tolerance, even after multiple impact loadings up to 50 J, which agree with previously conducted non-linear structural analysis. A cyclic loading scenario with 8,000 simulated flight cycles in the context of research induces no significant growth of the impact damages and no deteriorating of the structural behaviour, respectively. Finally, the sandwich panel was used to investigate expected thermo-mechanical loadings during the takeoff and landing phases of the reference aircraft.

Structural analysis of an advanced centre box of vertical tail plane with a side panel from composite foam core sandwich structure

German Aerospace Congress 2011, Aug 25, 2011

Sandwich panels are increasingly used in aircraft structures due to their high specific bending s... more Sandwich panels are increasingly used in aircraft structures due to their high specific bending stiffness and hence excellent buckling stability. The objective of this work is to find rough sizing process of a composite sandwich panel incorporating multi-scale modelling techniques to substantiate structural capability of each level of test pyramid, and find a minimum number of tests required to validate the approaches. The numerical analysis of such hybrid structures by means of the finite element method (FEM) requires specific strategies regarding the degree of homogeneity of each component. The common modelling approach for solid laminate of carbon fibre reinforced plastics (CFRP) structures using an extended layered shell element formulation can also be applied in modelling of sandwich panels in the global FE-model. The sandwich core, which is thicker compared to the solid laminate CFRP skins, can be formulated as an additional layer between the two face skin layers. For more detailed modelling of the sandwich structure, e.g. a cut out of the global FE model (GFEM), a solid shell approach can be applied. Both of the monolithic skins are idealised using layered shell, while the sandwich core is represented by solid elements. For a hard foam core the solid elements are assigned to the core system according to their type, isotropic material for unreinforced foam or homogenised, anisotropic properties for a reinforced foam core system. The homogenised mechanical properties of the reinforced foam core can be determined using analytical or numerical approaches, in which for a numerical approach the textile profile or needles shaped foam reinforcements are modelled with shell and beam elements respectively. With some modifications the meso-mechanical FE-model can further be used e.g. through the application of explicit FEM for the determination of an impact damage or using the virtual crack closure technique (VCCT) method and a higher level of FE discretisation to assess the growth behaviour of damages. The non-linear FE analyses show a good agreement with the recorded panel deformations.

Long-term durability of CFRP foam core sandwich structures

The work presented in this article is directed towards the application of CFRP foam core sandwich... more The work presented in this article is directed towards the application of CFRP foam core sandwich structures as primary structures in commercial aviation. With closed cell rigid foams, it is possible to produce comparatively low priced high-integral sandwich components having a complex geometry in terms of a curved and a variable lateral cut. Sandwich structures are offering a good bending stiffness and strength to weight ratio. Thus, they are suited for using in structures which are at risk to fail by buckling. The investigations are focused on a CFRP sandwich structure with polymethacrylimide (PMI) foam core, named ROHACELLRIST. Besides good structural stability at thermal conditions, the foam is characterized by a good strength and stiffness to weight ratio. Primary structures in aircraft applications are exposed to a superposition of in-service loads and environmental conditions. The typical working loads in combination with environmental conditions were investigated. The structure needs a sizing with respect to large temperature changes and influences of humidity. Thus, the time, temperature, and moisture dependency of the mechanical behavior were studied for the single components of the structure and for the composite itself. Therefore, Finite Element Models on macroscopic level were built with reference to the experiments. For each in-service case, the residual stresses arising during manufacturing have to be regarded and quantified. During manufacturing, the sandwich structure is cured at 180C. Due to the different stiffnesses and coefficients of thermal expansion of the foam and the CFRP face sheets, residual stresses are induced by cooling down to service temperature. Among others, some tests were made at laterally closed CFRP sandwich structures with a storage time up to half a year at certain climate conditions. The aging process is not only controlled by external conditions, but also by a rearrangement of molecules, for example, the relaxation behavior of the PMI foam. Another question of the long-term behavior of the CFRP foam core sandwich structure is the characteristic of delamination of the face sheets from the inner core after an impact has occurred. To describe the crack growth behavior of the sandwich structure fracture mechanical principles can be used estimating the damage tolerance. Sandwich specimens with initial damage were loaded up to 3 million mechanical load cycles.

format_quoteHigher moisture content leads to increased strength by reducing manufacturing-induced residual tensions thanks to the recovery effect of the foam.format_quote

Patents by ichwan zuardy

Structural component comprising at least one main-load-bearing covering shell and a carrier structure for fixing the main-load-bearing covering shell, and flow body comprising such a structural component

Main Load Bearing Planking Shell and Structural Component and Flow Body Comprising Such a Main Load Bearing Planking Shell

According to the invention a main load bearing skin shell for a structural component is provided,... more According to the invention a main load bearing skin shell for a structural component is provided, wherein the skin shell for being affixed to a support component comprises an outer edge section with an outer edge and comprises: a connection region that does not comprise a core layer, which connection region extends along the edge with the inner skin section and the outer skin section, wherein in an end region of the core layer along the outer edge section of the skin shell reinforcement devices are integrated that project through the shear force absorbing core layer.
Keyword: Damage Tolerant Composite Sandwich Panel

Pressure Bulkhead for an Aircraft Fuselage (Lenticular Monolithic Structures)

A pressure bulkhead for an aircraft fuselage is depicted and described, having a skin element, wh... more A pressure bulkhead for an aircraft fuselage is depicted and described, having a skin element, which has a first surface and a second surface, as well as a circumferential edge and a center axis, and having a reinforcement assembly, which has a plurality of radially disposed reinforcement elements, which extend along the first surface in a radial direction between an outer end at the edge of the skin element and an inner end, which faces the center axis, wherein, as viewed in a cross section, which extends radially along the center axis, each of the radially disposed reinforcement elements defines a first contour line and defines a second contour line, which is located opposite said first contour line, wherein each contour line extends from the outer end of the radially disposed reinforcement elements to the inner of the skin elements.
Note: This is the monolithic version of the previous patent application number WO002013139716A1

Support Strut for Supporting Primary Components and Method for its Manufacturing (Engineering Plant Stem / Bionic)

A support strut for use as primary load-bearing structural component for the hinged coupling of a... more A support strut for use as primary load-bearing structural component for the hinged coupling of at least one additional primary load-bearing structural component. The support strut includes: a rod-shaped base body extending in a longitudinal direction, a fiber composite with an annular cross section, central hole originating from the first end of the base body, and with annular holes spaced apart relative to each other in the circumferential direction of the annular cross section and originating from the first end of base body as well as running along the longitudinal direction in the base body.

(Note: this is the patent publication of the structural technology discussed in the paper: "Application Potential of Bionic Optimized Design in the Aerospace."

Pressure Fuselage of an Aircraft with a Fuselage Shell and a Pressure Bulkhead Disposed Therein (Lenticular Sandwich Structures)

European Patent Office (EPO), Sep 26, 2017

The invention relates to a pressure bulkhead of an aircraft with a fuselage shell and a pressure ... more The invention relates to a pressure bulkhead of an aircraft with a fuselage shell and a pressure bulkhead disposed therein preferably in the rear region for forming a fuselage internal pressure region, which pressure bulkhead is attached on the edge in the interior of the fuselage shell, wherein the pressure bulkhead has a lenticular cross section and a sandwich construction that comprises a foam core sandwiched between two opposing exterior shells.

Aircraft Structural Assembly (Half-lenticular Sandwich Structures)

United States Patent & Trademark Office (USPTO), Nov 21, 2013

An aircraft structural assembly includes an area element which has a core and an outer layer. A f... more

Structural Element for an Aircraft or Spacecraft and Method for Producing such a Structural Element (Mass Tailoring)

United States Patent & Trademark Office (USPTO), Nov 11, 2014

The present invention provides a structural element, in particular for an aircraft or spacecraft,... more The present invention provides a structural element, in particular for an aircraft or spacecraft, comprising a core, the material density of which varies, at least in portions, in order to optimize the natural vibration behaviour of the tructural element ( optimization of mass distribution -> mass tailoring)

Structural Element for an Aircraft or Spacecraft and Method for Producing a Structural Element of this Type (Stiffness Tailoring)

United States Patent & Trademark Office (USPTO), Oct 28, 2014

The present invention provides a structural element, in particular for an aircraft or spacecraft,... more The present invention provides a structural element, in particular for an aircraft or spacecraft, comprising a core, the rigidity of which varies, at least in portions for optimizing the aeroelastic characteristic of the structural element ( optimization of stiffness distribution -> stiffness tailoring)

System and Method for Monitoring a Component in Production as well as in Service

European Patent Office (EPO), Dec 3, 2014

The present invention relates to a system and a method for monitoring an aircraft or spacecraft c... more The present invention relates to a system and a method for monitoring an aircraft or spacecraft component in production or in service, especially a fibre reinforced composite , and particularly for quality assurance of the component. The invention further relates to a component, particularly fibre reinforced composite, of an aircraft or spacecraft that is suitable for use in such a system or method, especially as a structural or load bearing member.

Apparatus and Method for Producing a Component and Aircraft Structure Component

United States Patent & Trademark Office (USPTO), Oct 14, 2014

An apparatus for producing a component includes a material storage tank for receiving a liquid ma... more An apparatus for producing a component includes a material storage tank for receiving a liquid material, a molding tool and a material supply line which connects the material storage tank to filling region of the molding tool. In the region of material supply line or filling of the molding tool an optial fibre has been arranged, into which at least one Fibre Bragg Grating sensor for detecting a parameter that is characteristic of the flow material is integrated.