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Peter H. Bull

Bio: Peter H. Bull is an academic researcher from Aalborg University. The author has contributed to research in topics: Sandwich-structured composite & Ballistic impact. The author has an hindex of 6, co-authored 21 publications receiving 347 citations. Previous affiliations of Peter H. Bull include Swedish National Defence College & Royal Institute of Technology.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the impact and indentation damage and its effect on the load carrying capacity of state-of-the-art carbon composite sandwich panels for marine applications is investigated.

104 citations

Journal ArticleDOI
TL;DR: In this article, a parametric study on impact damage resistance and residual strength of carbon fiber sandwich panels with carbon fiber-vinylester faces and PVC foam core is conducted. But the results of the study were limited to two different impactor geometries.
Abstract: A plastic micro buckling approach is investigated in order to see whether it can be used to analytically predict the residual strength of carbon fiber sandwich structures. A parametric study on impact damage resistance and residual strength of sandwich panels with carbon fiber-vinylester faces and PVC foam core is conducted. Two sandwich configurations are studied. The first configuration consists of thin faces and an intermediate density core, representative of a panel from a superstructure. The second configuration consists of thick faces and a high density core, representative of a panel from a hull. Two different impactor geometries are used. One spherical impactor and one pyramid shaped impactor are used in a drop weight rig to inflict low velocity impact damage of different energy levels in the face of the sandwich. The damages achieved ranges from barely visible damages to penetration of one face. Residual strength is tested using in-plane compression of the sandwich plates either instrumented with strain gauges or monitored with digital speckle photography.

87 citations

Journal ArticleDOI
TL;DR: In this article, non-crimp fabric (NCF) composite face sheet sandwich panels have been tested in compression after impact (CAI). Damage in the face sheets was characterised by fractography.
Abstract: In the present study, non-crimp fabric (NCF) composite face sheet sandwich panels have been tested in compression after impact (CAI). Damage in the face sheets was characterised by fractography. Co ...

65 citations

Journal ArticleDOI
TL;DR: In this article, an experimental and numerical investigation has been carried out to study the behavior of single and multiple laminated panels subjected to ballistic impact, where a pressurized air gun is used to shoot the impactor, which can attain sufficient velocity to penetrate all the laminates in a multiple laminate panel.

51 citations

01 Jan 2004
TL;DR: The exploitation of sandwich structures as a means to achieve high specific strength and stiffness is relatively new as discussed by the authors, therefore, the knowledge of its damage tolerance is limitedcompared to other stru...
Abstract: The exploitation of sandwich structures as a means toachieve high specific strength and stiffness is relatively new.Therefore, the knowledge of its damage tolerance is limitedcompared to other stru ...

21 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the low velocity impact behavior of composite sandwich panels consisting of woven carbon/epoxy facesheets and a PVC foam core was studied experimentally and a straightforward peak impact load estimation method gave good agreement with experimental results.
Abstract: Composite sandwich structures are susceptible to low velocity impact damage and thorough characterization of the loading and damage process during impact is important. The objective of this work is to study experimentally the low velocity impact behavior of sandwich panels consisting of woven carbon/epoxy facesheets and a PVC foam core. Instrumented panels were impacted with a drop mass setup and the load, strain, and deflection histories were recorded. Damage was characterized and quantified after the test. Results were compared with those of an equivalent static loading and showed that low velocity impact was generally quasi-static in nature except for localized damage. A straightforward peak impact load estimation method gave good agreement with experimental results. A contact force–indentation relationship was also investigated for the static loading case. Experimental results were compared with analytical and finite element model analysis to determine their effectiveness in predicting the indentation behavior of the sandwich panel.

181 citations

Journal ArticleDOI
TL;DR: In this article, a full 3D finite element model of impact on thick-section composites is developed, which includes initiation and progressive damage of the composite during impact and penetration over a wide range of impact velocities.

168 citations

Journal ArticleDOI
TL;DR: In this article, a vascular sandwich structure that appears as a conventional sandwich composite has been developed and tested, where the vascular network is used to deliver a healing agent from a remote reservoir to a region of damage via a vascular network.
Abstract: Impact damage can degrade the flexural strength of composite sandwich structures by over 50% due to a loss of skin support inducing localized skin buckling. Various self-healing methodologies have been applied to laminated composites but the concept of delivering a healing agent from a remote reservoir to a region of damage via a vascular network offers the potential for a robust and replenishable system housed in the core of a sandwich structure. In this pilot study a vascular sandwich structure that appears as a conventional sandwich composite has been developed and tested. The network has been shown to have negligible influence on the innate static mechanical properties of the host panel. Infiltration of the vascular network with a pre-mixed epoxy resin system after impact damage demonstrated a complete recovery of flexural failure mode and load. Infiltration with the same resin system from separate unmixed networks, where self-healing is initiated autonomously via mixing within the damage, has also been shown to fully recover undamaged failure load when both networks are successfully breached.

160 citations

Journal ArticleDOI
TL;DR: In this article, a self-healing sandwich panel was designed and manufactured, which consists of vascular networks carrying the two liquid components of an epoxy resin system, and tested in edgewise compression-after-impact to prove the concept.

158 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the damage tolerance of a composite sandwich structure composed of woven carbon/epoxy facesheets and a PVC foam core, and found that the facesheet delamination damage was quite detrimental to the load bearing capacity of the sandwich panel, highlighting the need for reliable damage detection techniques for composite sandwich structures.
Abstract: Assessing the residual mechanical properties of a sandwich structure is an important part of any impact study and determines how the structure can withstand post impact loading. The damage tolerance of a composite sandwich structure composed of woven carbon/epoxy facesheets and a PVC foam core was investigated. Sandwich panels were impacted with a falling mass from increasing heights until damage was induced. Impact damage consisted of delamination and permanent indentation in the impacted facesheets. The Compression After Impact (CAI) strength of sandwich columns sectioned from these panels was then compared with the strength of an undamaged column. Although not visually apparent, the facesheet delamination damage was found to be quite detrimental to the load bearing capacity of the sandwich panel, underscoring the need for reliable damage detection techniques for composite sandwich structures.

144 citations